@article {511236, title = {Identification of methyl coenzyme M reductase A (mcrA) genes associated with methane-oxidizing archaea}, journal = {Applied and Environmental Microbiology}, volume = {69}, number = {9}, year = {2003}, note = {

723MWTimes Cited:166Cited References Count:36

}, month = {Sep}, pages = {5483-5491}, abstract = {

Phylogenetic and stable-isotope analyses implicated two methanogen-like archaeal groups, ANME-1 and ANME-2, as key participants in the process of anaerobic methane oxidation. Although nothing is known about anaerobic methane oxidation at the molecular level, the evolutionary relationship between methane-oxidizing archaea (MOA) and methanogenic archaea raises the possibility that MOA have co-opted key elements of the methanogenic pathway, reversing many of its steps to oxidize methane anaerobically. In order to explore this hypothesis, the existence and genomic conservation of methyl coenzyme M reductase (MCR), the enzyme catalyzing the terminal step in methanogenesis, was studied in ANME-1 and ANME-2 archaea isolated from various marine environments. Clone libraries targeting a conserved region of the alpha subunit of MCR (mcrA) were generated and compared from environmental samples, laboratory-incubated microcosms, and fosmid libraries. Four out of five novel mcrA types identified from these sources were associated with ANME-1 or ANME-2 group members. Assignment of mcrA types to specific phylogenetic groups was based on environmental clone recoveries, selective enrichment of specific MOA and mcrA types in a microcosm, phylogenetic congruence between mcrA and small-subunit rRNA tree topologies, and genomic context derived from fosmid sequences. Analysis of the ANME-1 and ANME-2 mcrA sequences suggested the potential for catalytic activity based on conservation of active-site amino acids. These results provide a basis for identifying methanotrophic archaea with mcrA sequences and define a functional genomic link between methanogenic and methanotrophic archaea.

}, keywords = {anoxic marine-sediments, Bacteria, Biochemistry, consumption, environments, methanogenesis, oxidation, pcr amplification, phylogenetic analysis, ribosomal-rna}, isbn = {0099-2240}, author = {Hallam, S. J. and Girguis, P. R. and Preston, C. M. and Richardson, P. M. and Delong, E. F.} }