Identification of methyl coenzyme M reductase A(mcrA) genes associated with methane-oxidizing archaea

Journal Article · Mon Sep 01 04:00:00 EDT 2003 · Applied and Environmental Microbiology

DOI:https://doi.org/10.1128/AEM.69.9.5483-5491.2003· OSTI ID:823087

Hallam, Steven J ^[1]; Girguis, Peter R; Preston, Christina M; Richardson, Paul M; DeLong, Edward F

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1. LBNL Library

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 orANME-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.

• Research Organization: Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
• Sponsoring Organization: USDOE Director. Office of Science. Biological and Environmental Research Program, Lawrence Livermore National Laboratory contract W-7405-ENG-48, Los Alamos National Laboratory contract W-7405-ENG-36; David and Lucille Packard Foundation (US)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 823087
• Report Number(s): LBNL--53923
• Journal Information: Applied and Environmental Microbiology, Journal Name: Applied and Environmental Microbiology Journal Issue: 9 Vol. 69; ISSN AEMIDF; ISSN 0099-2240
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
60 APPLIED LIFE SCIENCES
AMINO ACIDS
COENZYMES
ENZYMES
FUNCTIONALS
GENES
HYPOTHESIS
METHANE
MICROCOSMS
OXIDATION
OXIDOREDUCTASES
PHYLOGENETIC AND STABLE-ISOTOPE ANALYSES IMPLICATED TWO METHANOGEN-LIKE ARCHAEAL GROUPS ANME-1 AND
TREES