Novel methylated triterpenoids of the gammacerane series from the nitrogen‐fixing bacterium <i>Bradyrhizobium japonicum</i> USDA 110

Bravo, Jean-Michel; Perzl, Michael; Härtner, Thomas; Kannenberg, Elmar L.; Rohmer, Michel

doi:10.1046/j.1432-1327.2001.01998.x

Cited by 73 publications

(56 citation statements)

References 46 publications

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“…Bacteria that contain the methylase are found in three different bacterial groups: the acidobacteria, the cyanobacteria, and one major subclade of the rhizobiales within the α-proteobacteria. Of these thirty bacteria, only ten have been tested for hopanoid production and all ten of these strains produce 2-methylhopanoids (17,20,26,27). There are seven Methylobacterium and two Cyanothece strains that have the methylase gene but these specific strains have not been tested for hopanoid production.…”

Section: Resultsmentioning

confidence: 99%

Identification of a methylase required for 2-methylhopanoid production and implications for the interpretation of sedimentary hopanes

Welander

Coleman

Sessions

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

207

179

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The rise of atmospheric oxygen has driven environmental change and biological evolution throughout much of Earth's history and was enabled by the evolution of oxygenic photosynthesis in the cyanobacteria. Dating this metabolic innovation using inorganic proxies from sedimentary rocks has been difficult and one important approach has been to study the distributions of fossil lipids, such as steranes and 2-methylhopanes, as biomarkers for this process. 2-methylhopanes arise from degradation of 2-methylbacteriohopanepolyols (2-MeBHPs), lipids thought to be synthesized primarily by cyanobacteria. The discovery that 2-MeBHPs are produced by an anoxygenic phototroph, however, challenged both their taxonomic link with cyanobacteria and their functional link with oxygenic photosynthesis. Here, we identify a radical SAM methylase encoded by the hpnP gene that is required for methylation at the C-2 position in hopanoids. This gene is found in several, but not all, cyanobacteria and also in α -proteobacteria and acidobacteria. Thus, one cannot extrapolate from the presence of 2-methylhopanes alone, in modern environments or ancient sedimentary rocks, to a particular taxonomic group or metabolism. To understand the origin of this gene, we reconstructed the evolutionary history of HpnP. HpnP proteins from cyanobacteria, Methylobacterium species, and other α-proteobacteria form distinct phylogenetic clusters, but the branching order of these clades could not be confidently resolved. Hence,it is unclear whether HpnP, and 2-methylhopanoids, originated first in the cyanobacteria. In summary, existing evidence does not support the use of 2-methylhopanes as biomarkers for oxygenic photosynthesis.biomarkers | cyanobacteria | hopanoids | phylogeny | radical SAM

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Section: Resultsmentioning

confidence: 99%

Identification of a methylase required for 2-methylhopanoid production and implications for the interpretation of sedimentary hopanes

Welander

Coleman

Sessions

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

207

179

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“…It is common for plant symbionts to provide fixed nitrogen to plants or utilize methanol, a byproduct of plant metabolism, as a carbon source (Bravo et al, 2001;Gourion et al, 2006;Meeks, 2009). We found that 74% of hpnP-containing bacteria had either nifD or moxF, which encode proteins necessary for nitrogen fixation and methanol utilization, respectively (Figure 1, middle ring).…”

Section: -Mebhp Production Is Niche Specific Jn Ricci Et Almentioning

confidence: 95%

“…and Nostoc spp. (Figure 1); (Knani et al, 1994;Bravo et al, 2001;Meeks, 2009). To assess whether this observation was non-random, we used the hypergeometric test calculated with the number of plant-associated bacteria estimated at the species level to alleviate bias in the data set.…”

Section: -Mebhp Production Is Niche Specific Jn Ricci Et Almentioning

confidence: 99%

Diverse capacity for 2-methylhopanoid production correlates with a specific ecological niche

et al. 2013

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Molecular fossils of 2-methylhopanoids are prominent biomarkers in modern and ancient sediments that have been used as proxies for cyanobacteria and their main metabolism, oxygenic photosynthesis. However, substantial culture and genomic-based evidence now indicates that organisms other than cyanobacteria can make 2-methylhopanoids. Because few data directly address which organisms produce 2-methylhopanoids in the environment, we used metagenomic and clone library methods to determine the environmental diversity of hpnP, the gene encoding the C-2 hopanoid methylase. Here we show that hpnP copies from alphaproteobacteria and as yet uncultured organisms are found in diverse modern environments, including some modern habitats representative of those preserved in the rock record. In contrast, cyanobacterial hpnP genes are rarer and tend to be localized to specific habitats. To move beyond understanding the taxonomic distribution of environmental 2-methylhopanoid producers, we asked whether hpnP presence might track with particular variables. We found hpnP to be significantly correlated with organisms, metabolisms and environments known to support plant-microbe interactions (P-valueo10 À 6 ); in addition, we observed diverse hpnP types in closely packed microbial communities from other environments, including stromatolites, hot springs and hypersaline microbial mats. The common features of these niches indicate that 2-methylhopanoids are enriched in sessile microbial communities inhabiting environments low in oxygen and fixed nitrogen with high osmolarity. Our results support the earlier conclusion that 2-methylhopanoids are not reliable biomarkers for cyanobacteria or any other taxonomic group, and raise the new hypothesis that, instead, they are indicators of a specific environmental niche.

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“…Tetrahymanol was first isolated from the ciliate protozoan Tetrahymena pyriformis (Mallory et al, 1963). Besides eukaryotes such as in ferns, fungi, and other ciliates, tetrahymanol was found in addition to hopanoids in the phototrophic purple non-sulfur bacterium Rhodopseudomonas palustris (Kleemann et al, 1990) and in the nitrogen-fixing bacterium Bradyrhizobium japonicum (Bravo et al, 2001). …”

Section: Cyclic Triterpenesmentioning

confidence: 99%

Biomarker and 16S rDNA evidence for anaerobic oxidation of methane and related carbonate precipitation in deep-sea mud volcanoes of the Sorokin Trough, Black Sea

et al. 2005

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Many mud volcanoes were recently discovered in the euxinic bottom waters of the Sorokin Trough (NE Black Sea). Three of them, i.e., NIOZ, Odessa, and Kazakov, were selected for a detailed biogeochemical investigation. Four methane-related carbonate crusts covered with microbial mats, and sediments (dmud brecciaT) from these mud volcanoes were collected during the 11th Training-Through-Research cruise (TTR-11) in 2001, the first finding of methanotrophic microbial mats associated with authigenic carbonates in the deep Black Sea. We measured the concentrations and d13 C values of methane and specific archaeal and bacterial lipids, and determined archaeal and bacterial 16S rRNA gene sequences. The d 13 C of the microbial lipids reflected the carbon isotopic values of the methane, indicating that methane was the main carbon source for microorganisms inducing carbonate formation. Anaerobic oxidation of methane (AOM) in these settings was performed by archaea affiliated with the so-called ANME-1 group. None of the identified archaeal sequences were closely related to known methanogens. The combined 16S rRNA gene sequence and biomarker data revealed a distinct difference in archaeal assemblage between the carbonate crusts and mud breccias. Besides gene sequences of sulfate-reducing bacteria, DNA analysis of bacterial communities revealed a diversity of bacteria with apparent contrasting metabolic properties. The methane utilization via AOM processes was detected in the uppermost sediments where it subsequently induces authigenic carbonate precipitation most probably below seafloor. The results of integrated biomarker and 16S rRNA gene study reveal a crucial role of AOM processes in formation of authigenic carbonates in methane seep environments. D

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Novel methylated triterpenoids of the gammacerane series from the nitrogen‐fixing bacterium Bradyrhizobium japonicum USDA 110

Cited by 73 publications

References 46 publications

Identification of a methylase required for 2-methylhopanoid production and implications for the interpretation of sedimentary hopanes

Identification of a methylase required for 2-methylhopanoid production and implications for the interpretation of sedimentary hopanes

Diverse capacity for 2-methylhopanoid production correlates with a specific ecological niche

Biomarker and 16S rDNA evidence for anaerobic oxidation of methane and related carbonate precipitation in deep-sea mud volcanoes of the Sorokin Trough, Black Sea

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