The exceptional form and function of the giant bacterium Ca. Epulopiscium viviparus revolves around its sodium motive force.

Autor:	Sannino DR; Department of Microbiology, Cornell University, Ithaca, NY 14853., Arroyo FA; Department of Microbiology, Cornell University, Ithaca, NY 14853., Pepe-Ranney C; Soil & Crop Sciences Section, School of Integrative Plant Sciences, Cornell University, Ithaca, NY 14853., Chen W; Department of Microbiology, Cornell University, Ithaca, NY 14853., Volland JM; Laboratory for Research in Complex Systems, Menlo Park, CA 94025.; Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA 94720., Elisabeth NH; Department of Energy Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720., Angert ER; Department of Microbiology, Cornell University, Ithaca, NY 14853.
Jazyk:	angličtina
Zdroj:	Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2023 Dec 26; Vol. 120 (52), pp. e2306160120. Date of Electronic Publication: 2023 Dec 18.
DOI:	10.1073/pnas.2306160120
Abstrakt:	Epulopiscium spp. are the largest known heterotrophic bacteria; a large cigar-shaped individual is a million times the volume of Escherichia coli . To better understand the metabolic potential and relationship of Epulopiscium sp. type B with its host Naso tonganus , we generated a high-quality draft genome from a population of cells taken from a single fish. We propose the name Candidatus Epulopiscium viviparus to describe populations of this best-characterized Epulopiscium species. Metabolic reconstruction reveals more than 5% of the genome codes for carbohydrate active enzymes, which likely degrade recalcitrant host-diet algal polysaccharides into substrates that may be fermented to acetate, the most abundant short-chain fatty acid in the intestinal tract. Moreover, transcriptome analyses and the concentration of sodium ions in the host intestinal tract suggest that the use of a sodium motive force (SMF) to drive ATP synthesis and flagellar rotation is integral to symbiont metabolism and cellular biology. In natural populations, genes encoding both F-type and V-type ATPases and SMF generation via oxaloacetate decarboxylation are among the most highly expressed, suggesting that ATPases synthesize ATP and balance ion concentrations across the cell membrane. High expression of these and other integral membrane proteins may allow for the growth of its extensive intracellular membrane system. Further, complementary metabolism between microbe and host is implied with the potential provision of nitrogen and B vitamins to reinforce this nutritional symbiosis. The few features shared by all bacterial behemoths include extreme polyploidy, polyphosphate synthesis, and thus far, they have all resisted cultivation in the lab. Competing Interests: Competing interests statement:The authors declare no competing interest.
Databáze:	MEDLINE
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