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Growth and Localization of Polyhydroxybutyrate Granules in Ralstonia eutropha

Beeby, Morgan and Cho, Mimi and Stubbe, JoAnne and Jensen, Grant J. (2012) Growth and Localization of Polyhydroxybutyrate Granules in Ralstonia eutropha. Journal of Bacteriology, 194 (5). pp. 1092-1099. ISSN 0021-9193. PMCID PMC3294789. doi:10.1128/JB.06125-11.

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The bacterium Ralstonia eutropha forms cytoplasmic granules of polyhydroxybutyrate that are a source of biodegradable thermoplastic. While much is known about the biochemistry of polyhydroxybutyrate production, the cell biology of granule formation and growth remains unclear. Previous studies have suggested that granules form either in the inner membrane, on a central scaffold, or in the cytoplasm. Here we used electron cryotomography to monitor granule genesis and development in 3 dimensions (3-D) in a near-native, “frozen-hydrated” state in intact Ralstonia eutropha cells. Neither nascent granules within the cell membrane nor scaffolds were seen. Instead, granules of all sizes resided toward the center of the cytoplasm along the length of the cell and exhibited a discontinuous surface layer more consistent with a partial protein coating than either a lipid mono- or bilayer. Putatively fusing granules were also seen, suggesting that small granules are continually generated and then grow and merge. Together, these observations support a model of biogenesis wherein granules form in the cytoplasm coated not by phospholipid but by protein. Previous thin-section electron microscopy (EM), fluorescence microscopy, and atomic force microscopy (AFM) results to the contrary may reflect both differences in nucleoid condensation and specimen preparation-induced artifacts.

Item Type:Article
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URLURL TypeDescription CentralArticle
Beeby, Morgan0000-0001-6413-9835
Jensen, Grant J.0000-0003-1556-4864
Additional Information:© 2012 American Society for Microbiology. Received 2 September 2011 Accepted 9 December 2011. Published ahead of print 16 December 2011. This work was supported by NIH GM49171 to J. Stubbe and Howard Hughes Medical Institute funding to G. J. Jensen. We thank Wesley Chen for assistance in manual reconstruction of tomograms.
Funding AgencyGrant Number
Howard Hughes Medical Institute (HHMI)UNSPECIFIED
Issue or Number:5
PubMed Central ID:PMC3294789
Record Number:CaltechAUTHORS:20120316-151333425
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Official Citation:Growth and Localization of Polyhydroxybutyrate Granules in Ralstonia eutropha Morgan Beeby, Mimi Cho, JoAnne Stubbe, and Grant J. Jensen J. Bacteriol. March 2012 194:1092-1099; published ahead of print 16 December 2011 , doi:10.1128/JB.06125-11
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:29755
Deposited By: Ruth Sustaita
Deposited On:16 Mar 2012 22:39
Last Modified:09 Nov 2021 19:29

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