Biosynthesis of 2-methylbacteriohopanepolyols by an anoxygenic phototroph

Sky E. Rashby, Alex L. Sessions, Roger E. Summons, Dianne K. Newman*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    217 Citations (Scopus)


    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.

    Original languageEnglish
    Pages (from-to)15099-15104
    Number of pages6
    JournalProceedings of the National Academy of Sciences of the United States of America
    Issue number38
    Publication statusPublished - 18 Sep 2007


    • 2-Methyhopanes
    • Biomarkers
    • Cyanobacteria
    • Rhodopseudomonas palustris


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