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Hopanoids Play a Role in Membrane Integrity and pH Homeostasis in Rhodopseudomonas palustris TIE-1

Welander, Paula V. and Hunter, Ryan C. and Zhang, Lichun and Sessions, Alex L. and Summons, Roger E. and Newman, Dianne K. (2009) Hopanoids Play a Role in Membrane Integrity and pH Homeostasis in Rhodopseudomonas palustris TIE-1. Journal of Bacteriology, 191 (19). pp. 6145-6156. ISSN 0021-9193. PMCID PMC2747905. http://resolver.caltech.edu/CaltechAUTHORS:20091002-105243373

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Abstract

Sedimentary hopanes are pentacyclic triterpenoids that serve as biomarker proxies for bacteria and certain bacterial metabolisms, such as oxygenic photosynthesis and aerobic methanotrophy. Their parent molecules, the bacteriohopanepolyols (BHPs), have been hypothesized to be the bacterial equivalent of sterols. However, the actual function of BHPs in bacterial cells is poorly understood. Here, we report the physiological study of a mutant in Rhodopseudomonas palustris TIE-1 that is unable to produce any hopanoids. The deletion of the gene encoding the squalene-hopene cyclase protein (Shc), which cyclizes squalene to the basic hopene structure, resulted in a strain that no longer produced any polycyclic triterpenoids. This strain was able to grow chemoheterotrophically, photoheterotrophically, and photoautotrophically, demonstrating that hopanoids are not required for growth under normal conditions. A severe growth defect, as well as significant morphological damage, was observed when cells were grown under acidic and alkaline conditions. Although minimal changes in shc transcript expression were observed under certain conditions of pH shock, the total amount of hopanoid production was unaffected; however, the abundance of methylated hopanoids significantly increased. This suggests that hopanoids may play an indirect role in pH homeostasis, with certain hopanoid derivatives being of particular importance.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1128/JB.00460-09DOIArticle
http://jb.asm.org/cgi/content/abstract/191/19/6145PublisherArticle
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2747905/PubMed CentralArticle
ORCID:
AuthorORCID
Sessions, Alex L.0000-0001-6120-2763
Newman, Dianne K.0000-0003-1647-1918
Additional Information:© 2009 American Society for Microbiology. Received 3 April 2009; accepted 6 July 2009. This work was supported by grants from the NASA Exobiology Program to A.L.S., D.K.N., and R.E.S. and an NSF Postdoctoral Minority Fellowship to P.V.W. D.K.N. is an Investigator of the Howard Hughes Medical Institute. We thank David Doughty and Alex Poulain for comments on the manuscript and members of the Newman laboratory for helpful discussions.
Funders:
Funding AgencyGrant Number
NASAUNSPECIFIED
NSF Postdoctoral Minority FellowshipUNSPECIFIED
Howard Hughes Medical Institute (HHMI)UNSPECIFIED
PubMed Central ID:PMC2747905
Record Number:CaltechAUTHORS:20091002-105243373
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20091002-105243373
Official Citation:Welander, Paula V., Hunter, Ryan C., Zhang, Lichun, Sessions, Alex L., Summons, Roger E., Newman, Dianne K. Hopanoids Play a Role in Membrane Integrity and pH Homeostasis in Rhodopseudomonas palustris TIE-1 J. Bacteriol. 2009 191: 6145-6156
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:16166
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:06 Oct 2009 21:12
Last Modified:24 Oct 2017 15:53

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