The methanogenic archaeon Methanosarcina barkeri synthesizes protoheme via precorrin-2, which is formed from uroporphyrinogen III in two consecutive methylation reactions utilizing S-adenosyl-L-methionine. The existence of this pathway, previously exclusively found in the sulfate-reducing delta-proteobacterium Desulfovibrio vulgaris, was demonstrated for M. barkeri via the incorporation of two ...

We report here a comparative analysis of the genome sequence of Methanosarcina barkeri with those of Methanosarcina acetivorans and Methanosarcina mazei. The genome of M. barkeri is distinguished by having an organization that is well conserved with respect to the other Methanosarcina spp. in the region proximal to the origin of replication, with interspecies gene similarities as high as 95%. H...

Methane emission was inhibited by aluminium ion in paddy fields. Addition of Al3+ (20 mM) to the culture medium containing cells of pure Methanosarcina barkeri, inhibited methanogenesis. Methanogenic co-factor, F-420, was isolated and purified from Methanosarcina barkeri MS. Spectrophotometric and spectrofluorometric analysis of interaction between co-factor, F-420, and Al3+ revealed that they ...

Viable methanogens have been detected in dry, aerobic environments such as dry reservoir sediment, dry rice paddies and aerobic desert soils, which suggests that methanogens have mechanisms for long-term survival in a desiccated state. In this study, we quantified the survival rates of the methanogenic archaeon Methanosarcina barkeri after desiccation under conditions equivalent to the driest e...

The DNA sequences of the argG genes of Methanosarcina barkeri MS and Methanococcus vannielii were determined. The polypeptide products of these methanogen genes have amino acid sequences which are 50% identical to each other and 38% identical to the amino acid sequence encoded by the exons of the human argininosuccinate synthetase gene. Introns in the human chromosomal gene separate regions whi...

Pyrrolysine, the 22nd cotranslationally inserted amino acid, was found in the Methanosarcina barkeri monomethylamine methyltransferase protein in a position that is encoded by an in-frame UAG stop codon in the mRNA. M. barkeri encodes a special amber suppressor tRNA (tRNA(Pyl)) that presumably recognizes this UAG codon. It was reported that Lys-tRNA(Pyl) can be formed by the aminoacyl-tRNA synt...

Methanosarcina acetivorans C2A encodes three putative hydrogenases, including one cofactor F(420)-linked (frh) and two methanophenazine-linked (vht) enzymes. Comparison of the amino acid sequences of these putative hydrogenases to those of Methanosarcina barkeri and Methanosarcina mazei shows that each predicted subunit contains all the known residues essential for hydrogenase function. The DNA...