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Identification and characterization of Rhodopseudomonas palustris TIE-1 hopanoid biosynthesis mutants

Welander, P. V. and Doughty, D. M. and Wu, C. -H. and Mehay, S. and Summons, R. E. and Newman, D. K. (2012) Identification and characterization of Rhodopseudomonas palustris TIE-1 hopanoid biosynthesis mutants. Geobiology, 10 (2). pp. 163-177. ISSN 1472-4677. http://resolver.caltech.edu/CaltechAUTHORS:20120302-134849665

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Abstract

Hopanes preserved in both modern and ancient sediments are recognized as the molecular fossils of bacteriohopanepolyols, pentacyclic hopanoid lipids. Based on the phylogenetic distribution of hopanoid production by extant bacteria, hopanes have been used as indicators of specific bacterial groups and/or their metabolisms. However, our ability to interpret them ultimately depends on understanding the physiological roles of hopanoids in modern bacteria. Toward this end, we set out to identify genes required for hopanoid biosynthesis in the anoxygenic phototroph Rhodopseudomonas palustris TIE-1 to enable selective control of hopanoid production. We attempted to delete 17 genes within a putative hopanoid biosynthetic gene cluster to determine their role, if any, in hopanoid biosynthesis. Two genes, hpnH and hpnG, are required to produce both bacteriohopanetetrol and aminobacteriohopanetriol, whereas a third gene, hpnO, is required only for aminobacteriohopanetriol production. None of the genes in this cluster are required to exclusively synthesize bacteriohopanetetrol, indicating that at least one other hopanoid biosynthesis gene is located elsewhere on the chromosome. Physiological studies with the different deletion mutants demonstrated that unmethylated and C_30 hopanoids are sufficient to maintain cytoplasmic but not outer membrane integrity. These results imply that hopanoid modifications, including methylation of the A-ring and the addition of a polar head group, may have biologic functions beyond playing a role in membrane permeability.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1111/j.1472-4669.2011.00314.xDOIArticle
http://onlinelibrary.wiley.com/doi/10.1111/j.1472-4669.2011.00314.x/abstractPublisherArticle
ORCID:
AuthorORCID
Newman, D. K.0000-0003-1647-1918
Additional Information:© 2012 Blackwell Publishing Ltd. Received 17 June 2011; accepted 21 November 2011. Article first published online: 4 Jan. 2012. This work was supported by grants from the National Aeronautics and Space Administration (NASA) Exobiology Program (DKN and RES), the NASA Astrobiology Institute (RES), the National Science Foundation Postdoctoral Minority Fellowship (PVW), and the Camille and Henry Dreyfus Environmental Chemistry Fellowship (CHW). DKN is an Investigator of The Howard Hughes Medical Institute. We thank Turner Bohlen and Nathan Nocera for help in constructing the plasmids necessary to delete hpnO and hpnG. We also thank Prof. Tanja Bosak for providing laboratory space and equipment and Prof. Stephen K. Farrand for pSRKGm.
Funders:
Funding AgencyGrant Number
NASAUNSPECIFIED
NSF Postdoctoral Minority FellowshipUNSPECIFIED
Camille and Henry Dreyfus FoundationUNSPECIFIED
Howard Hughes Medical Institute (HHMI)UNSPECIFIED
Record Number:CaltechAUTHORS:20120302-134849665
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20120302-134849665
Official Citation:WELANDER, P. V., DOUGHTY, D. M., WU, C.-H., MEHAY, S., SUMMONS, R. E. and NEWMAN, D. K. (2012), Identification and characterization of Rhodopseudomonas palustris TIE-1 hopanoid biosynthesis mutants. Geobiology, 10: 163–177. doi: 10.1111/j.1472-4669.2011.00314.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:29570
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:02 Mar 2012 22:23
Last Modified:24 Oct 2017 16:15

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