Evidence for the synthesis of the multi-positional isomers of monounsaturated fatty acid in Methylococcus capsusatus by the anaerobic pathway

Jahnke, L. L.

doi:10.1016/0378-1097(89)90035-9

Cited by 3 publications

(3 citation statements)

References 13 publications

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“…Our analysis supports the existence of an anaerobic mechanism for unsaturated fatty acid synthesis in M. capsulatus, as proposed by Jahnke and Diggs (1989) on the basis of biochemical data . A predicted enzyme 3-hydroxydecanoyl-ACP-dehydratase (MCA2878) appears to catalyze an alternative dehydratase reaction at the C 10 level of fatty acid synthesis, followed by a synthase reaction carried out by 3-oxoacyl-acyl carrier protein (ACP) synthase (MCA2879), resulting in cis -vaccenate (18:1, cis -Δ11).…”

Section: Resultssupporting

confidence: 89%

Genomic Insights into Methanotrophy: The Complete Genome Sequence of Methylococcus capsulatus (Bath)

Ward¹,

Larsen

Sakwa³

et al. 2004

PLoS Biol

301

278

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Methanotrophs are ubiquitous bacteria that can use the greenhouse gas methane as a sole carbon and energy source for growth, thus playing major roles in global carbon cycles, and in particular, substantially reducing emissions of biologically generated methane to the atmosphere. Despite their importance, and in contrast to organisms that play roles in other major parts of the carbon cycle such as photosynthesis, no genome-level studies have been published on the biology of methanotrophs. We report the first complete genome sequence to our knowledge from an obligate methanotroph, Methylococcus capsulatus (Bath), obtained by the shotgun sequencing approach. Analysis revealed a 3.3-Mb genome highly specialized for a methanotrophic lifestyle, including redundant pathways predicted to be involved in methanotrophy and duplicated genes for essential enzymes such as the methane monooxygenases. We used phylogenomic analysis, gene order information, and comparative analysis with the partially sequenced methylotroph Methylobacterium extorquens to detect genes of unknown function likely to be involved in methanotrophy and methylotrophy. Genome analysis suggests the ability of M. capsulatus to scavenge copper (including a previously unreported nonribosomal peptide synthetase) and to use copper in regulation of methanotrophy, but the exact regulatory mechanisms remain unclear. One of the most surprising outcomes of the project is evidence suggesting the existence of previously unsuspected metabolic flexibility in M. capsulatus, including an ability to grow on sugars, oxidize chemolithotrophic hydrogen and sulfur, and live under reduced oxygen tension, all of which have implications for methanotroph ecology. The availability of the complete genome of M. capsulatus (Bath) deepens our understanding of methanotroph biology and its relationship to global carbon cycles. We have gained evidence for greater metabolic flexibility than was previously known, and for genetic components that may have biotechnological potential.

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Section: Resultssupporting

confidence: 89%

Genomic Insights into Methanotrophy: The Complete Genome Sequence of Methylococcus capsulatus (Bath)

Ward¹,

Larsen

Sakwa³

et al. 2004

PLoS Biol

301

278

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“…are digested by, and incorporated into, the host bivalves (6,7,38). As for a marine bivalve nutritionally dependent on an endosymbiotic methanotroph belonging to the ␥-Proteobacteria, monounsaturated C 16 fatty acids, the dominant fatty acids in the symbiont-bearing tissue as well as in the free-living methanotrophic relatives of the endosymbiont (22,24), are absent in the symbiont-free tissues, which implies that the fatty acids synthesized by the endosymbiont are not utilized by the host bivalve. The presence of methylsterols, known to be produced only by methanotrophic bacteria in symbiont-free tissue, suggests that the methylsterols are released from the endosymbiont and taken up by the host (24).…”

Section: Discussionmentioning

confidence: 99%

Novel Chemoautotrophic Endosymbiosis between a Member of the Epsilonproteobacteria and the Hydrothermal-Vent Gastropod Alviniconcha aff. hessleri (Gastropoda: Provannidae) from the Indian Ocean

Suzuki

Sasaki

Suzuki

et al. 2005

Appl Environ Microbiol

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The hydrothermal-vent gastropod Alviniconcha aff. hessleri from the Kairei hydrothermal field on the Central Indian Ridge houses bacterium-like cells internally in its greatly enlarged gill. A single 16S rRNA gene sequence was obtained from the DNA extract of the gill, and phylogenetic analysis placed the source organism within a lineage of the epsilon subdivision of the Proteobacteria. Fluorescence in situ hybridization analysis with an oligonucleotide probe targeting the specific epsilonproteobacterial subgroup showed the bacterium densely colonizing the gill filaments. Carbon isotopic homogeneity among the gastropod tissue parts, regardless of the abundance of the endosymbiont cells, suggests that the carbon isotopic composition of the endosymbiont biomass is approximately the same as that of the gastropod. Compound-specific carbon isotopic analysis revealed that fatty acids from the gastropod tissues are all 13C enriched relative to the gastropod biomass and that the monounsaturated C16 fatty acid that originates from the endosymbiont is as 13C enriched relative to the gastropod biomass as that of the epsilonproteobacterial cultures grown under chemoautotrophic conditions. This fractionation pattern is most likely due to chemoautotrophy based on the reductive tricarboxylic-acid (rTCA) cycle and subsequent fatty acid biosynthesis from 13C-enriched acetyl coenzyme A. Enzymatic characterization revealed evident activity of several key enzymes of the rTCA cycle, as well as the absence of ribulose-1,5-bisphosphate carboxylase/oxygenase activity in the gill tissue. The results from anatomic, molecular phylogenetic, bulk and compound-specific carbon isotopic, and enzymatic analyses all support the inference that a novel nutritional strategy relying on chemoautotrophy in the epsilonproteobacterial endosymbiont is utilized by the hydrothermal-vent gastropod from the Indian Ocean. The discrepancies between the data of the present study and those of previous ones for Alviniconcha gastropods from the Pacific Ocean imply that at least two lineages of chemoautotrophic bacteria, phylogenetically distinct at the subdivision level, occur as the primary endosymbiont in one host animal type.

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“…This fact is supported by the slight variation in ␦ 13 C values observed for phospholipid FAME (Table 3). While the gill tissue contained somewhat heavier 16:1 molecules, it is important to note that in methanotrophic bacteria unsaturated fatty acid synthesis occurs by a novel anaerobic mechanism and results in 16:1 isomers that are isotopically heavier than the corresponding saturated 16:0 isomers (26,48). Data on the higher hydrocarbons isolated from gill tissues, together with measured fractionation factors for M. capsulatus, can be used to construct a model to describe the expected isotopic compositions of mussel metabolites.…”

Section: Vol 61 1995 Methanotrophic Biomarkers In Cold-seep Mussel mentioning

confidence: 99%

Identification of methanotrophic lipid biomarkers in cold-seep mussel gills: chemical and isotopic analysis

Jahnke

Summons

Dowling

et al. 1995

Appl Environ Microbiol

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A lipid analysis of the tissues of a cold-seep mytilid mussel collected from the Louisiana slope of the Gulf of Mexico was used in conjunction with a compound-specific isotope analysis to demonstrate the presence of methanotrophic symbionts in the mussel gill tissue and to demonstrate the host's dependence on bacterially synthesized metabolic intermediates. The gill tissue contained large amounts of group-specific methanotrophic biomarkers, bacteriohopanoids, 4-methylsterols, lipopolysaccharide-associated hydroxy fatty acids, and type I-specific 16:1 fatty acid isomers with bond positions at ⌬8, ⌬10, and ⌬11. Only small amounts of these compounds were detected in the mantle or other tissues of the host animal. A variety of cholesterol and 4-methylsterol isomers were identified as both free and steryl esters, and the sterol double bond positions suggested that the major bacterially derived gill sterol [11.0% 4␣-methyl-cholesta-8(14),24-dien-3␤-ol] was converted to host cholesterol (64.2% of the gill sterol was cholest-5-en-3␤-ol). The stable carbon isotope values for gill and mantle preparations were, respectively, ؊59.0 and ؊60.4‰ for total tissue, ؊60.6 and ؊62.4‰ for total lipids, ؊60.2 and ؊63.9‰ for phospholipid fatty acids, and ؊71.8 and ؊73.8‰ for sterols. These stable carbon isotope values revealed that the relative fractionation pattern was similar to the patterns obtained in pure culture experiments with methanotrophic bacteria (R. E. Summons, L. L. Jahnke, and Z. Roksandic, Geochim. Cosmochim. Acta 58:2853-2863, 1994) further supporting the conversion of the bacterial methylsterol pool.

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Evidence for the synthesis of the multi-positional isomers of monounsaturated fatty acid in Methylococcus capsusatus by the anaerobic pathway

Cited by 3 publications

References 13 publications

Genomic Insights into Methanotrophy: The Complete Genome Sequence of Methylococcus capsulatus (Bath)

Genomic Insights into Methanotrophy: The Complete Genome Sequence of Methylococcus capsulatus (Bath)

Novel Chemoautotrophic Endosymbiosis between a Member of the Epsilonproteobacteria and the Hydrothermal-Vent Gastropod Alviniconcha aff. hessleri (Gastropoda: Provannidae) from the Indian Ocean

Identification of methanotrophic lipid biomarkers in cold-seep mussel gills: chemical and isotopic analysis

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