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Biosynthesis of 2-methylbacteriohopanepolyols by an anoxygenic phototroph

Rashby, Sky E. and Sessions, Alex L. and Summons, Roger E. and Newman, Dianne K. (2007) Biosynthesis of 2-methylbacteriohopanepolyols by an anoxygenic phototroph. Proceedings of the National Academy of Sciences of the United States of America, 104 (38). pp. 15099-15014. ISSN 0027-8424. PMCID PMC1986619. doi:10.1073/pnas.0704912104.

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Sedimentary 2-methyhopanes have been used as biomarker proxies for cyanobacteria, the only known bacterial clade capable of oxygenic photosynthesis and the only group of organisms found thus far to produce abundant 2-methylbacteriohopanepolyols (2-MeBHPs). Here, we report the identification of significant quantities of 2-MeBHP in two strains of the anoxygenic phototroph Rhodopseudomonas palustris. Biosynthesis of 2-MeBHP can occur in the absence of O2, deriving the C-2 methyl group from methionine. The relative abundance of 2-MeBHP varies considerably with culture conditions, ranging from 13.3% of total bacteriohopanepolyol (BHP) to trace levels of methylation. Analysis of intact BHPs reveals the presence of methylated bacteriohopane-32,33,34,35-tetrol but no detectable methylation of 35-aminobacteriohopane-32,33,34-triol. Our results demonstrate that an anoxygenic photoautotroph is capable of generating 2-MeBHPs and show that the potential origins of sedimentary 2-methylhopanoids are more diverse than previously thought.

Item Type:Article
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URLURL TypeDescription CentralArticle Information
Sessions, Alex L.0000-0001-6120-2763
Summons, Roger E.0000-0002-7144-8537
Newman, Dianne K.0000-0003-1647-1918
Additional Information:© 2007 The National Academy of Sciences of the USA. Edited by John M. Hayes, Woods Hole Oceanographic Institution, Woods Hole, MA, and approved August 3, 2007 (received for review May 25, 2007). Published online on September 11, 2007, 10.1073/pnas.0704912104. With profound sadness we record that Sky Rashby passed away on August 25, 2007, while this manuscript was in press. This is his work and his first scientific publication. We mourn the tragic loss of this talented young scientist and compassionate individual. We thank members of the D.K.N. and A.L.S. laboratories, Chad Vecitis, and Nathan Dalleska for technical assistance; Helen Talbot and Tsege Embaye for helpful discussion; Jack Meeks (University of California, Davis, CA) and Arthur Grossman (Stanford University, Stanford, CA) for providing cyanobacterial strains; and Linda Jahnke (National Aeronautics and Space Administration Ames Research Center, Moffett Field, CA) for advice and cyanobacterial samples. This work was supported by grants from the Packard Foundation and Howard Hughes Medical Institute (to D.K.N.) and the National Science Foundation (to A.L.S.) and the National Aeronautics and Space Administration Exobiology Program (to R.E.S.). Author contributions: S.E.R., A.L.S., and D.K.N. designed research; S.E.R. and R.E.S. performed research; S.E.R. and R.E.S. contributed new reagents/analytic tools; S.E.R., A.L.S., R.E.S., and D.K.N. analyzed data; and S.E.R., A.L.S., and D.K.N. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission. This article contains supporting information online at
Funding AgencyGrant Number
David and Lucile Packard FoundationUNSPECIFIED
Howard Hughes Medical Institute (HHMI)UNSPECIFIED
Subject Keywords:2-methyhopanes; biomarkers; cyanobacteria; Rhodopseudomonas palustris
Issue or Number:38
PubMed Central ID:PMC1986619
Record Number:CaltechAUTHORS:RASpnas07
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Official Citation:Sky E. Rashby, Alex L. Sessions, Roger E. Summons, and Dianne K. Newman Biosynthesis of 2-methylbacteriohopanepolyols by an anoxygenic phototroph PNAS 2007 104 (38) 15099-15104; published ahead of print September 11, 2007, doi:10.1073/pnas.0704912104
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9731
Deposited By: Tony Diaz
Deposited On:11 Mar 2008
Last Modified:08 Nov 2021 21:01

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