title: Metagenome and mRNA expression analyses of anaerobic methanotrophic archaea of the ANME-1 group.
abstract: Microbial consortia mediating the anaerobic oxidation of methane with sulfate are composed of methanotrophic Archaea (ANME) and Bacteria related to sulfate-reducing Deltaproteobacteria. Cultured representatives are not available for any of the three ANME clades. Therefore, a metagenomic approach was applied to assess the genetic potential of ANME-1 archaea. In total, 3.4 Mbp sequence information was generated based on metagenomic fosmid libraries constructed directly from a methanotrophic microbial mat in the Black Sea. These sequence data represent, in 30 contigs, about 82-90% of a composite ANME-1 genome. The dataset supports the hypothesis of a reversal of the methanogenesis pathway. Indications for an assimilatory, but not for a dissimilatory sulfate reduction pathway in ANME-1, were found. Draft genome and expression analyses are consistent with acetate and formate as putative electron shuttles. Moreover, the dataset points towards downstream electron-accepting redox components different from the ones known from methanogenic archaea. Whereas catalytic subunits of [NiFe]-hydrogenases are lacking in the dataset, genes for an [FeFe]-hydrogenase homologue were identified, not yet described to be present in methanogenic archaea. Clustered genes annotated as secreted multiheme c-type cytochromes were identified, which have not yet been correlated with methanogenesis-related steps. The genes were shown to be expressed, suggesting direct electron transfer as an additional possible mode to shuttle electrons from ANME-1 to the bacterial sulfate-reducing partner.
authors.affiliation: Max Planck Institute for Marine Microbiology, Celsiusstrasse 1, 28359 Bremen, Germany. ameyerdi@mpi-bremen.de
authors.forename: Anke
authors.initials: A
authors.lastname: Meyerdierks
authors.forename: Michael
authors.initials: M
authors.lastname: Kube
authors.forename: Ivaylo
authors.initials: I
authors.lastname: Kostadinov
authors.forename: Hanno
authors.initials: H
authors.lastname: Teeling
authors.forename: Frank Oliver
authors.initials: FO
authors.lastname: Glöckner
authors.forename: Richard
authors.initials: R
authors.lastname: Reinhardt
authors.forename: Rudolf
authors.initials: R
authors.lastname: Amann
mesh_terms: D001483:Base Sequence; D045304:Cytochromes c / Q000235:genetics; D019605:Euryarchaeota / Q000145:classification / Q000235:genetics* / Q000378:metabolism*; D006864:Hydrogenase / Q000235:genetics; D007506:Iron-Sulfur Proteins / Q000235:genetics; D054892:Metagenome; D056186:Metagenomics; D008697:Methane / Q000378:metabolism; D008969:Molecular Sequence Data; D009792:Oceans and Seas; D010084:Oxidation-Reduction; D012333:RNA, Messenger / Q000378:metabolism*
chemical_list: D007506:Iron-Sulfur Proteins; D012333:RNA, Messenger; D045304:Cytochromes c; C118830:iron hydrogenase; D006864:Hydrogenase; D008697:Methane