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Methanosarcina barkeri

About: Methanosarcina barkeri is a research topic. Over the lifetime, 703 publications have been published within this topic receiving 32151 citations.


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Journal ArticleDOI
TL;DR: In this article, electron paramagnetic resonance (EPR) and optical spectroscopy were used for electron transfer and methyl-group reduction during aceticlastic methanogenesis.
Abstract: Membranes prepared from Methanosarcina barkeri cultured on acetate were examined for electron carriers using electron paramagnetic resonance (EPR) and optical spectroscopy. EPR analysis of membrane suspensions demonstrated multiple iron-sulfur centers of the 4Fe-4S type, a hihg-spin heme-like species and possibly rebredoxin. Optical spectroscopy demonstrated that a b-type cytochrome was reduced by molecular hydrogen and oxidized by methyl coenzyme M. A membrane-bound hydrogenase activity (14 μM · min−1 (mg protein)−1) was detected. This suggests a putative role for cytochrome b and hydrogenase in electron transfer and methyl-group reduction during aceticlastic methanogenesis.

32 citations

Journal ArticleDOI
TL;DR: Interspecies hydrogen transfer between rumen holotrich ciliate protoza and methanogenic bacteria has been demonstrated and the metabolite profile of Isotricha spp.
Abstract: Interspecies hydrogen transfer between rumen holotrich ciliate protoza and methanogenic bacteria has been demonstrated. As a result of the metabolic interaction with Methanosarcina barkeri, the metabolite profile of Isotricha spp. was altered and the production of butyrate and lactate was suppressed in the presence of the methanogen.Use of membrane‐inlet mass spectrometry confirmed that the presence of rumen holotrich ciliates reduced the apparent sensitivity of methanogenesis to the inhibitory effects of oxygen; a gas phase concentration of 7·4 kPa oxygen was required to inhibit methanogenesis in the presence of protozoa, while in pure cultures of M. barkeri, methanogenesis was inhibited by a gas phase oxygen concentration of 1·0 kPa.

32 citations

Journal ArticleDOI
TL;DR: The finding that one more protein fraction was found essential for the overall reaction and, more specifically, for formation of the methylated MT1 intermediate demonstrated that the protein was involved in the activation of MT1 and was called methyltransferase activation protein.
Abstract: Methanol:5-hydroxybenzimidazolylcobamide methyltransferase (MT1) is the first of two enzymes required for transfer of the methyl group of methanol to 2-mercaptoethanesulfonic acid in Methanosarcina barkeri. MT1 binds the methyl group of methanol to its corrinoid prosthetic group only when the central cobalt atom of the corrinoid is present in the highly reduced Co(I) state. However, upon manipulation of MT1 and even during catalysis, the enzyme becomes inactivated as the result of Co(I) oxidation. Reactivation requires H2, hydrogenase, and ATP. Ferredoxin stimulated the apparent reaction rate of methyl group transfer. Here we report that one more protein fraction was found essential for the overall reaction and, more specifically, for formation of the methylated MT1 intermediate. The more of the protein that was present, the shorter the delay of the start of methyl group transfer. The maximum velocity of methyl transfer was not substantially affected by these varying amounts of protein. This demonstrated that the protein was involved in the activation of MT1. Therefore, it was called methyltransferase activation protein.

32 citations

Journal ArticleDOI
TL;DR: Differences in stoichiometry within ribosomal stalk complexes from bacteria, eukaryotes, and archaea in situ on the ribosome are considered in the context of convergence evolution.

32 citations

Journal ArticleDOI
01 Sep 2002-Archaea
TL;DR: Phylogenetic analysis of deduced amino acid sequences for the nitrogenase structural genes of M. mazei Gö1 showed that they are most closely related to Methanosarcina barkeri nif2 genes, and also closely resemble those for the corresponding nif products of the gram-positive bacterium C. acetobutylicum.
Abstract: The mesophilic methanogenic archaeon Methanosarcina mazei strain Go1 is able to utilize molecular nitrogen (N2) as its sole nitrogen source. We have identified and characterized a single nitrogen fixation (nif) gene cluster in M. mazei Go1 with an approximate length of 9 kbp. Sequence analysis revealed seven genes with sequence similarities to nifH, nifI1, nifI2, nifD, nifK, nifE and nifN, similar to other diazotrophic methanogens and certain bacteria such as Clostridium acetobutylicum, with the two glnB-like genes (nifI1 and nifI2) located between nifH and nifD. Phylogenetic analysis of deduced amino acid sequences for the nitrogenase structural genes of M. mazei Go1 showed that they are most closely related to Methanosarcina barkeri nif2 genes, and also closely resemble those for the corresponding nif products of the gram-positive bacterium C. acetobutylicum. Northern blot analysis and reverse transcription PCR analysis demonstrated that the M. mazei nif genes constitute an operon transcribed only under nitrogen starvation as a single 8 kb transcript. Sequence analysis revealed a palindromic sequence at the transcriptional start site in front of the M. mazei nifH gene, which may have a function in transcriptional regulation of the nif operon.

32 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20237
202212
202112
202012
20197
201818