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Published May 2021 | Submitted
Journal Article Open

Measuring gas vesicle dimensions by electron microscopy


Gas vesicles (GVs) are cylindrical or spindle‐shaped protein nanostructures filled with air and used for flotation by various cyanobacteria, heterotrophic bacteria, and Archaea. Recently, GVs have gained interest in biotechnology applications due to their ability to serve as imaging agents and actuators for ultrasound, magnetic resonance and several optical techniques. The diameter of GVs is a crucial parameter contributing to their mechanical stability, buoyancy function and evolution in host cells, as well as their properties in imaging applications. Despite its importance, reported diameters for the same types of GV differ depending on the method used for its assessment. Here, we provide an explanation for these discrepancies and utilize electron microscopy (EM) techniques to accurately estimate the diameter of the most commonly studied types of GVs. We show that during air drying on the EM grid, GVs flatten, leading to a ~1.5‐fold increase in their apparent diameter. We demonstrate that GVs' diameter can be accurately determined by direct measurements from cryo‐EM samples or alternatively indirectly derived from widths of flat collapsed and negatively stained GVs. Our findings help explain the inconsistency in previously reported data and provide accurate methods to measure GVs dimensions.

Additional Information

© 2021 The Protein Society. Issue Online: 12 April 2021; Version of Record online: 11 March 2021; Accepted manuscript online: 27 February 2021; Manuscript accepted: 22 February 2021; Manuscript received: 22 January 2021. This work was supported by the National Institutes of Health (grant R35-GM122588 to G.J.J. and R01-EB018975 to M.G.S.) and the Caltech Center for Environmental Microbial Interactions (CEMI). Electron microscopy was performed in the Beckman Institute Resource Center for Transmission Electron Microscopy at Caltech. Related research in the Shapiro Laboratory is also supported by the Heritage Medical Research Institute, the Pew Scholarship in the Biomedical Sciences, and the Packard Fellowship for Science and Engineering. Author Contributions: Przemysław Dutka: Conceptualization; methodology; investigation; formal analysis; visualization; writing – original draft preparation; writing – review editing. Dina Malounda: Investigation. Lauren Ann Metskas: Investigation. Songye Chen: Investigation. Robert C. Hurt: Investigation. George J. Lu: Investigation. Grant J. Jensen: Conceptualization; writing – review editing; supervision; funding acquisition. Mikhail G. Shapiro: Conceptualization; writing – review editing; supervision; funding acquisition. The authors declare no competing interests.

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Submitted - 2021.01.22.427725v1.full.pdf


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August 22, 2023
September 11, 2023