DETAILED ACTION
Election/Restrictions
Applicant’s election without traverse of Group I, claims 1-15 and the Species of shell protein comprising an N-terminal region of the GvpA gene from Anabaena flos-aquae with Met1 to Val51 of SEQ ID NO: 1 with a C-terminal region of the GvpB gene from Bacillus megaterium with Asp52 to Ile88 of SEQ ID NO: 2; and a gas species of Bacillus megaterium gvpU, in the reply filed on 10/16/25 is acknowledged.
Claims 3 and 16-20 are withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected invention.
Claims 1, 2 and 4-15 read on the elected species and are currently under examination.
Claim Rejections - 35 USC § 112-2nd paragraph
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 1, 2 and 4-15 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claims 1, 2 and 4-15 are rejected on the basis that it contains an improper Markush grouping of alternatives. See In re Harnisch, 631 F.2d 716, 721-22 (CCPA 1980) and Ex parte Hozumi, 3 USPQ2d 1059, 1060 (Bd. Pat. App. & Int. 1984). A Markush grouping is proper if the alternatives defined by the Markush group (i.e., alternatives from which a selection is to be made in the context of a combination or process, or alternative chemical compounds as a whole) share a “single structural similarity” and a common use. A Markush grouping meets these requirements in two situations. First, a Markush grouping is proper if the alternatives are all members of the same recognized physical or chemical class or the same art-recognized class, and are disclosed in the specification or known in the art to be functionally equivalent and have a common use. Second, where a Markush grouping describes alternative chemical compounds, whether by words or chemical formulas, and the alternatives do not belong to a recognized class as set forth above, the members of the Markush grouping may be considered to share a “single structural similarity” and common use where the alternatives share both a substantial structural feature and a common use that flows from the substantial structural feature. See MPEP § 2117.
The Markush grouping of gas vesicles comprising different shell proteins and different gas vesicle assembly protein is improper because the alternatives defined by the Markush grouping do not share both a single structural similarity and a common use for the following reasons: these are different products, not mere species of one another. They are different fusions with different amino acid sequences, different structures.
To overcome this rejection, Applicant may set forth each alternative (or grouping of patentably indistinct alternatives) within an improper Markush grouping in a series of independent or dependent claims and/or present convincing arguments that the group members recited in the alternative within a single claim in fact share a single structural similarity as well as a common use. It is noted that ‘shell protein’ is not a structural similarity as it comprises many different proteins/amino acid sequences and the claims has numerous different combinations that are different inventions, not species of one another. Accordingly, the non-elected “species” should be removed from the claim.
Claim 1 is vague and indefinite because it recites “at least 95% sequence identity” to a protein in part i) and ii), but does not provide a reference sequence. The claim must disclose a sequence identifier, e.g., to the amino acid sequence set forth in SEQ ID NO: X, in order for the claim to be complete. While the specification can be used to provide definitive support, the claims are not read in a vacuum. Rather, the claim must be definite and complete in and of itself. Limitations from the specification will not be read into the claims. The claims as they stand are incomplete and fail to provide adequate structural properties to allow for one to identify what is being claimed. Appropriate clarification and/or correction is required.
Claims 1, 2, and 4-15 are vague and indefinite due to the use of a name alone to describe the gas vesicle assembly protein, e.g., gvpU, or just the term “shell protein” (claim 4). The mere recitation of a name to describe the invention is not sufficient to satisfy the Statute's requirement of adequately describing and setting forth the inventive concept. The claim should provide any structural properties, such as the amino acid sequence of the protein which would allow for one to identify the protein without ambiguity. The mere recitation of a name does not adequately define the claimed protein. Appropriate clarification and/or correction is required.
Claim 5 is vague and indefinite for the recitation “wherein the modified shell protein consists of one amino acid sequence.” What amino acid sequence may this protein comprise? A protein inherently has ‘one amino acid sequence’ so this wording is confusing. Do Applicants intend to recite that this is a fusion protein or something else? The metes and bounds of the invention cannot be understood. Appropriate clarification and/or correction is required.
Claim Rejections - 35 USC § 112-Written Description
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.
Claims 1, 2 and 4-15 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention.
Instant claim 1 recites:
a gas vesicle composition comprising a modified shell protein with any first fragment that is 20-88 amino acids in length and at least 95% sequence identity with any wild-type gas vesicle shell protein and a second fragment which is that is 20-88 amino acids in length and at least 95% sequence identity with any wild-type gas vesicle shell protein; and at least one of the gas vesicle proteins selected from: Bacillus megaterium gvpR, Bacillus megaterium gvpN, Bacillus megaterium gvpF, Bacillus megaterium gvpG, Bacillus megaterium gvpL, Bacillus megaterium gvpS, Bacillus megaterium gvpK, Bacillus megaterium gvpJ, Bacillus megaterium gvpT, Bacillus megaterium gvpU, Anabaena flos-aquae gvpN, Anabaena flos-aquae gvpJ, Anabaena flos- aquae gvpK, Anabaena flos-aquae gvpF, Anabaena flos-aquae gvpG, Anabaena flos-aquae gvpV, and Anabaena flos-aquae gvpW.
The instant specification does not provide adequate written description for the breadth of these claims. The specification does teach A gas vesicle composition comprising a modified shell protein which comprises an N-terminal region of the GvpA gene from Anabaena flos-aquae with Met1 to Val51 of SEQ ID NO: 1 and the C-terminal region of the GvpB gene from Bacillus megaterium consisting of Asp52 to Ile88 of SEQ ID NO: 2; and the gas vesicle assembly protein gvpU from Bacillus megaterium.
To fulfill the written description requirements set forth under 35 USC § 112, first paragraph, the specification must describe at least a substantial number of the members of the claimed genus, or alternatively describe a representative member of the claimed genus, which shares a particularly defining feature common to at least a substantial number of the members of the claimed genus, which would enable the skilled artisan to immediately recognize and distinguish its members from others, so as to reasonably convey to the skilled artisan that Applicant has possession the claimed invention. Applicants have not described the genus of claimed gas vesicle compositions such that the specification might reasonably convey to the skilled artisan that Applicants had possession of the claimed invention at the time the application was filed.
Gas vesicles are intracellular, protein-coated, and hollow organelles found in cyanobacteria and halophilic archaea, e.g., there is wide variation among gas vesicles and shell proteins (Ning et al Journal of Bacteriology (1998), 180(9), 2450-2458).
With the written description of a genus, however, merely drawing a fence around a perceived genus is not a description of the genus. One needs to show that one has truly invented the genus, i.e., that one has conceived and described sufficient representative species encompassing the breadth of the genus. Otherwise, one has only a research plan, leaving it to others to explore the unknown contours of the claimed genus. See Ariad, 598 F.3d at 1353 (The written description requirement guards against claims that "merely recite a description of the problem to be solved while claiming all solutions to it and . . . cover any compound later actually invented and determined to fall within the claim's functional boundaries."). Abbvie Deutschland GmbH & Co. v. Janssen Biotech, Inc., 759 F.3d 1285, 1300, 111 U.S.P.Q.2d 1780, 1790, 2014 BL 183329, 12 (Fed. Cir. 2014).
To fulfill the written description requirements set forth under 35 USC § 112, first paragraph, the specification must describe at least a substantial number of the members of the claimed genus, or alternatively describe a representative member of the claimed genus, which shares a particularly defining feature common to at least a substantial number of the members of the claimed genus, which would enable the skilled artisan to immediately recognize and distinguish its members from others, so as to reasonably convey to the skilled artisan that Applicant has possession the claimed invention. Applicants have not described the genus of claimed gas vesicle compositions such that the specification might reasonably convey to the skilled artisan that Applicants had possession of the claimed invention at the time the application was filed.
The purpose of the "written description" requirement is broader than tomerely explain how to "make and use"; the applicant must convey with reasonableclarity to those skilled in the art that, as of the filing date sought, he or she was inpossession of the invention. The invention is, for purposes of the "writtendescription" inquiry, whatever is now claimed. See Vas-Cath, Inc. v. Mahurkar,935 F.2d 1555, 1563-64, 19 USPQ2d 1111, 1117 (Federal Circuit, 1991).Furthermore, the written description provision of 35 USC § 112 is severable fromits enablement provision; and adequate written description requires more than amere statement that it is part of the invention and reference to a potential methodfor isolating it. The nucleic acid [product] itself is required. See Fiers v. Revel, 25 USPQ2d 1601, 1606 (CAFC 1993) and Amgen Inc. V. Chugai Pharmaceutical Co. Ltd., 18 USPQ2d 1016. Possession may be shown in a variety of ways including description of an actual reduction to practice, or by showing the invention was 'ready for patenting' such as by disclosure of drawings or structural chemical formulas that show that the invention was complete, or by describing distinguishing identifying characteristics sufficient to show that the applicant was in possession of the claimed invention" (Id. at 1104). Moreover, because the claims encompass a genus of variant species, an adequate written description of the claimed invention must include sufficient description of at least a representative number of species by actual reduction to practice, reduction to drawings, or by disclosure of relevant, identifying characteristics sufficient to show that Applicant was in possession of the claimed genus. An objective standard for determining compliance with the written description requirement is, "does the description clearly allow persons of ordinary skill in the art to recognize that he or she invented what is claimed." In re Gosteli, 872 F.2d 1008, 1012, 10 USPQ2d 1614, 1618 (Fed. Cir. 1989). To satisfy the written description requirement, an applicant must convey with reasonable clarity to those skilled in the art that, as of the filing date sought, he or she was in possession of the invention, and that the invention, in that context, is whatever is now claimed. Vas-Cath, Inc. v. Mahurkar, 935 F.2d 1555, 1563-64, 19 USPQ2d 1111, 1117 (Fed. Cir. 1991) and MPEP 2163.02.
However, factual evidence of an actual reduction to practice has not been disclosed by Applicant in the specification; nor has Applicant shown the invention was "ready for patenting" by disclosure of drawings or structural chemical formulas that show that the invention was complete; nor has Applicant described distinguishing identifying characteristics sufficient to show that Applicant were in possession of the claimed invention at the time the application was filed. For inventions in an unpredictable art, adequate written description of a genus which embraces widely variant species cannot be achieved by disclosing only one species within the genus'" (Id. at 1106); accordingly, it follows that an adequate written description of a genus cannot be achieved in the absence of a disclosure of at least one species within the genus. The scope of the claim includes numerous structural variants, and the genus is highly variant because a significant number of structural differences between genus members is permitted.
One of skill in the art would reasonably conclude that the disclosure fails to provide a representative number of species to describe the genus, and thus, that the applicant was not in possession of the claimed genus. The claimed subject matter is not supported by an adequate written description because a representative number of species has not been described.
The instant claim also allows for any fragments from any shell proteins that are 20-88 amino acid in lengths; both a first and second fragment with at least 95% sequence identity to any wild-type gas shell protein, anywhere from the protein.
Devos et al., (Proteins: Structure, Function and Genetics, 2000, Vol. 41: 98-107), teach that the results obtained by analyzing a significant number of true sequence similarities, derived directly from structural alignments, point to the complexity of function prediction. Different aspects of protein function, including (i) enzymatic function classification, (ii) functional annotations in the form of key words, (iii) classes of cellular function, and conservation of binding sites can only be reliably transferred between similar sequences to a modest degree. The reason for this difficulty is a combination of the unavoidable database inaccuracies and plasticity of proteins (Abstract, page 98) and the analysis poses interesting questions about the reliability of current function prediction exercises and the intrinsic limitation of protein function prediction (Column 1, paragraph 3, page 99) and conclude that "Despite widespread use of database searching techniques followed by function inference as standard procedures in Bioinformatics, the results presented here illustrate that transfer of function between similar sequences involves more difficulties than commonly believed. Our data show that even true pair-wise sequence relations, identified by their structural similarity, correspond in many cases to different functions (column 2, paragraph 2, and page 105).
Whisstock et al., (Quarterly Reviews of Biophysics 2003, Vol. 36 (3): 307-340,) also highlight the difficulties associated with "Prediction of protein function from protein sequence and structure": "To reason from sequence and structure to function is to step onto much shakier ground", closely related proteins can change function, either through divergence to a related function or by recruitment for a very different function, in such cases, assignment of function on the basis of homology, in the absence of direct experimental evidence, will give the wrong answer (page 309, paragraph 4), it is difficult to state criteria for successful prediction of function, since function is in principle a fuzzy concept. Given three sequences, it is possible to decide which of the three possible pairs is most closely related. Given three structures, methods are also available to measure and compare similarity of the pairs. However, in many cases, given three protein functions, it would be more difficult to choose the pair with most similar function, although it is possible to define metrics for quantitative comparisons of different protein sequences and structures, this is more difficult for proteins of different functions (page 312, paragraph 5), in families of closely related proteins, mutations usually conserve function but modulate specificity i.e., mutations tend to leave the backbone conformation of the pocket unchanged but to affect the shape and charge of its lining, altering specificity (page 313, paragraph 4), although the hope is that highly similar proteins will share similar functions, substitutions of a single, critically placed amino acid in an active-site residue may be sufficient to alter a protein's role fundamentally (page 323, paragraph 1). C. This finding is reinforced in the following scientific teachings for specific proteins in the art that suggest, even highly structurally homologous polypeptides do not necessarily share the same function and many functionally similar proteins will have little or no structural homology to disclosed proteins. For example, proteins having similar structure have different activities (structure does not always correlate to function);
Because the art is unpredictable, in accordance with the Written Description Guidelines and the scope of the claim includes numerous structural variants and the genus is highly variant because a significant number of structural differences between genus members is permitted. The specification does not describe any members of the claimed genus by complete structure. One of skill in the art would reasonably conclude that the disclosure fails to provide a representative number of species to describe the genus, and thus, that the applicant was not in possession of the claimed genus. The claimed subject matter is not supported by an adequate written description because a representative number of species has not been described.
There are no drawings or structural formulas disclosed of any of thesefragments or variants of the claimed shell fusion polypeptides. There is no teaching in the specification regarding which part of the structure can be varied and still produce a structure which has functional activity. Based on the lack of knowledge and predictability in the art, those of ordinary skill in the art would not conclude that the applicant was in possession of the claimed genus of gas vesicles.
Applicant is referred to the revised guidelines concerning compliance with the written description requirement of U.S.C. 112, first paragraph, published in the Official Gazette and also available at www.uspto.gov
Claim Rejections - 35 USC § 112-Scope of Enablement
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.
Claims 1, 2 and 4-15 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, because the specification, while being enabling for:
A gas vesicle composition comprising a modified shell protein which comprises an N-terminal region of the GvpA gene from Anabaena flos-aquae with Met1 to Val51 of SEQ ID NO: 1 and the C-terminal region of the GvpB gene from Bacillus megaterium consisting of Asp52 to Ile88 of SEQ ID NO: 2; and the gas vesicle assembly protein gvpU from Bacillus megaterium.
, does not reasonably provide enablement for the full breadth of the claims which allow for a gas vesicle composition comprising a modified shell protein with any first fragment that is 20-88 amino acids in length and at least 95% sequence identity with any wild-type gas vesicle shell protein and a second fragment which is that is 20-88 amino acids in length and at least 95% sequence identity with any wild-type gas vesicle shell protein; and at least one of the gas vesicle proteins selected from: Bacillus megaterium gvpR, Bacillus megaterium gvpN, Bacillus megaterium gvpF, Bacillus megaterium gvpG, Bacillus megaterium gvpL, Bacillus megaterium gvpS, Bacillus megaterium gvpK, Bacillus megaterium gvpJ, Bacillus megaterium gvpT, Bacillus megaterium gvpU, Anabaena flos-aquae gvpN, Anabaena flos-aquae gvpJ, Anabaena flos- aquae gvpK, Anabaena flos-aquae gvpF, Anabaena flos-aquae gvpG, Anabaena flos-aquae gvpV, and Anabaena flos-aquae gvpW.
The specification does not enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and/or use the invention commensurate in scope with these claims. The instant claim also allows for any fragments from any shell proteins that are 20-88 amino acid in lengths; both a first and second fragment with at least 95% sequence identity to any wild-type gas shell protein, anywhere from the protein.
The instant specification recites that it was a critical unmet need to develop gas-filled agents with < 100 nm hydrodynamic radius for ultrasound technology. See paragraph:
[0022] The present disclosure provides sub-50 nm, stable, free-floating gas-filled protein nanostructures. The presently disclosed protein nanostructures show that genetic mutations of the major shell proteins can alter GVs into diamond-shaped nanostructures of smaller diameters. A homogenous population of these sub-50 nm GVs, which are referenced herein as s50GVs, are favorable in that they can be produced in bacteria, purified through simple centrifugation, and remain free-floating and stable for months. Evaluation of the presently disclosed protein nanostructions demonstrates their beneficial ability to extravasate from lymph drainage into lymphatic tissues, which would gain access to the immune cells and cancer cells important nowadays for the development of tumor vaccines, early diagnostics of tumor metastasis, and the treatment of infectious diseases (Irvine and Dane, 2020; Schudel et al., 2019). The presently disclosed s50GVs form bubbles with a beneficial combination of small hydrodynamic radius and free-floating capability. To this end, protein nanostructures of the present disclosure may be useful in a range of applications, including but not limited to enabling ultrasound technologies to cells previously inaccessible by microbubbles and nanobubbles. Additional details on these aspects and more are provided above and in the sections that follow.
The instant specification teaches:
Paragraph [0060] In a recent design and screening of various shell protein variants composed of hybrid protein sequences from Anabaena flos-aquae and Bacillus megaterium (Li et al., 2023), a genetic variant was uncovered that consists of MAVEKTNSSSSLAEVIDRILDKGIVIDAWVRVSLVGIELLAIEARIVIASV (SEQ ID NO: 1), the N-terminus to the 2nd B-sheet of gvpA from A. flos-aquae (residues M1-V51), and DTWLRYAEAVGLLRDDVEENGLPERSNSSEGQPRESI (SEQ ID NO: 2), the 2nd α helix to the C-terminus of gvpB from B. megaterium (residues D52-I88) (FIG. 1B). After test expression of this genetic variant of GVs in E. coli and centrifugally assisted flotation, a visible white layer was observed, indicating the presence of GVs. Upon the TEM imaging, these GVs were discovered to display a homogenous population of diamond-shape nanostructures with a diameter less than 50 nm (FIG. 1C), thus representing a highly interesting type of ultrasmall GVs that were termed s50GV.
However, there are no working examples or description for any other gas vesicle composition that meets these structural requirements or the breadth allowed in claim 1, for example, e.g., any shell proteins in part (a) of claim 1, including variants of any shell protein from any source. Gas vesicles are intracellular, protein-coated, and hollow organelles found in cyanobacteria and halophilic archaea, e.g., there is wide variation among gas vesicles and shell proteins (Ning et al Journal of Bacteriology (1998), 180(9), 2450-2458). The specification does not enable any other first and second fragments of a shell protein or fragment thereof which would behave similarly.
Claims 8, 11, 12 and 14 recite fragments at least 95% identical to SEQ ID NO: 1 and/or SEQ ID NO: 2. While the specification states that substitutions, additions, or deletions, may be made to the defined sequences; however, the specification provides no guidance as which amino acids may be changed without causing a detrimental effect to the enzyme and with the added enzymatic function requirement. It is unpredictable as to which amino acids could be removed and which could be added. While it is known that many amino acid substitutions are possible in any given protein, the position within the protein’s sequence where amino acid substitutions can be made with a reasonable expectation of success are limited. Other positions are critical to the protein’s structure/function relationship, e.g., such as various positions or regions directly involved in binding, catalysis in providing the correct three-dimensional spatial orientation of binding and catalytic sites. These regions can tolerate only very little or no substitutions. Selective point mutation to one key residue could eliminate the function of the polypeptide. It could eliminate its functional properties. If the range of decreased binding ability after single point mutation of a protein antigen varies, one could expect point mutations in the protein antigen to cause varying degrees of loss of protection/function, depending on the relative importance to the binding interaction of the altered residue. Alternatively, the combined effects of multiple changes, as instantly claimed, in an antigenic determinant could again result in loss of function. A protein having multiple point mutations, or accumulated point mutations at key residues could create a new antigen that is precipitously or progressively unrecognizable. As stated above, Applicants have not shown the particular substitution and the result it produces. Applicants have provided no guidance to enable one of ordinary skill in the art how to determine, without undue experimentation, the effects of different amino substitutions and the nature and extent of the changes that can be made. It is expensive and time consuming to make amino acid substitutions at more than one position, in a particular region of the protein, in view of the many fold possibilities for change in structure and the uncertainty as to what utility will be possessed. See Mikayama et al. (Nov.1993. Proc.Natl.Acad.Sci. USA, vol. 90 : 10056-10060) which teaches that the three-dimensional structure of molecules is important for their biological function and even a single amino acid difference may account for markedly different biological activities. Amino acids owe their ‘significance’ to their inclusion in a pattern which is directly involved in recognition by, and binding to, the receptor and the significance of the particular amino acids and sequences for different amino acids cannot be predicted a priori, but must be determined from case to case by painstaking experimental study. The instant claims allow for substitutions with amino acids of vastly different properties and they do not recite the specific changes in the claims.
Genentech Inc. v. Novo Nordisk A/S (CAFC) 42 USPQ2d 1001 clearly states: “Patent protection is granted in return for an enabling disclosure of an invention, not for vague intimations of general ideas that may or may not be workable. See Brenner v. Manson, 383 U.S. 519, 536, 148 USPQ 689, 696 (1966) (stating, in context of the utility requirement, that "a patent is not a hunting license. It is not a reward for the search, but compensation for its successful conclusion.") Tossing out the mere germ of an idea does not constitute enabling disclosure. While every aspect of a generic claim certainly need not have been carried out by an inventor, or exemplified in the specification, reasonable detail must be provided in order to enable members of the public to understand and carry out the invention.”
Status of claims
No claims are allowed.
Pertinent art, not presently relied upon:
Ning et al Journal of Bacteriology (1998), 180(9), 2450-2458
Gas vesicles are intracellular, protein-coated, and hollow
organelles found in cyanobacteria and halophilic archaea. They are
permeable to ambient gases by diffusion and provide buoyancy, enabling
cells to move upwards in liq. to access oxygen and/or light. In
halobacteria, gas vesicle production is encoded in a 9-kb cluster of 14
genes (4 of known function). In cyanobacteria, the no. of genes involved has not been detected. The authors now report the cloning and sequence anal.of an 8,142-bp cluster of 15 putative gas vesicle genes (gvp) from Bacillus megaterium VT1660 and their functional expression in Escherichia coli.
Li et al Nature Microbiology (2024), 9(4), 1021-1035
Gas vesicles (GVs) are microbial protein organelles that support
cellular buoyancy. GV engineering has multiple applications, including
reporter gene imaging, acoustic control and payload delivery. GVs often
cluster into a honeycomb pattern to minimize occupancy of the cytosol.
The underlying mol. mechanism and the influence on cellular physiol.
remain unknown. Using genetic, biochem. and imaging approaches, here we
identify GvpU from Priestia megaterium as a protein that regulates GV
clustering in vitro and upon expression in Escherichia coli. GvpU binds
to the C-terminal tail of the core GV shell protein and undergoes a
phase transition to form clusters in subsatd. soln. These properties of
GvpU tune GV clustering and directly modulate bacterial fitness. GV
variants can be designed with controllable sensitivity to GvpU-mediated
clustering, enabling design of genetically tunable biosensors. Our
findings elucidate the mol. mechanisms and functional roles of GV
clustering, enabling its programmability for biomedical applications.
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/JENNIFER E GRASER/ Primary Examiner, Art Unit 1645 11/4/25