{"entryType":"UniProtKB reviewed (Swiss-Prot)","primaryAccession":"Q2RW98","uniProtkbId":"MARK_RHORT","entryAudit":{"firstPublicDate":"2026-01-28","lastAnnotationUpdateDate":"2026-09-02","lastSequenceUpdateDate":"2006-01-24","entryVersion":92,"sequenceVersion":1},"annotationScore":3.0,"organism":{"scientificName":"Rhodospirillum rubrum (strain ATCC 11170 / ATH 1.1.1 / DSM 467 / LMG 4362 / NCIMB 8255 / S1)","taxonId":269796,"lineage":["Bacteria","Pseudomonadati","Pseudomonadota","Alphaproteobacteria","Rhodospirillales","Rhodospirillaceae","Rhodospirillum"]},"proteinExistence":"1: Evidence at protein level","proteinDescription":{"recommendedName":{"fullName":{"evidences":[{"evidenceCode":"ECO:0000305"}],"value":"Methylthio-alkane reductase catalytic subunit beta"},"ecNumbers":[{"evidences":[{"evidenceCode":"ECO:0000269","source":"PubMed","id":"32855335"}],"value":"1.18.-.-"}]}},"genes":[{"geneName":{"evidences":[{"evidenceCode":"ECO:0000303","source":"PubMed","id":"32855335"}],"value":"marK"},"orderedLocusNames":[{"evidences":[{"evidenceCode":"ECO:0000312","source":"EMBL","id":"ABC21597.1"}],"value":"Rru_A0793"}]}],"comments":[{"texts":[{"evidences":[{"evidenceCode":"ECO:0000269","source":"PubMed","id":"32855335"}],"value":"Component of a nitrogenase-like enzyme system, which is required for the anaerobic assimilation of sulfur from common environmental volatile organic sulfur compounds (VOSCs) to support growth and methionine metabolism (PubMed:32855335). Catalyzes the conversion of dimethyl sulfide (DMS) to methane, ethyl methyl sulfide (EMS) to ethane, and (2-methylthio)ethanol (MT-EtOH) to ethylene (PubMed:32855335). The three reactions also produce methanethiol, which serves as the immediate precursor to methionine (PubMed:32855335). This nitrogenase-like enzyme system does not exhibit nitrogenase activity (PubMed:32855335)"}],"commentType":"FUNCTION"},{"commentType":"CATALYTIC ACTIVITY","reaction":{"name":"dimethyl sulfide + AH2 = methane + methanethiol + A","reactionCrossReferences":[{"database":"Rhea","id":"RHEA:81431"},{"database":"ChEBI","id":"CHEBI:13193"},{"database":"ChEBI","id":"CHEBI:16007"},{"database":"ChEBI","id":"CHEBI:16183"},{"database":"ChEBI","id":"CHEBI:17437"},{"database":"ChEBI","id":"CHEBI:17499"}],"evidences":[{"evidenceCode":"ECO:0000269","source":"PubMed","id":"32855335"}]},"physiologicalReactions":[{"directionType":"left-to-right","reactionCrossReference":{"database":"Rhea","id":"RHEA:81432"},"evidences":[{"evidenceCode":"ECO:0000269","source":"PubMed","id":"32855335"}]}]},{"commentType":"CATALYTIC ACTIVITY","reaction":{"name":"methyl ethyl sulfide + AH2 = ethane + methanethiol + A","reactionCrossReferences":[{"database":"Rhea","id":"RHEA:81435"},{"database":"ChEBI","id":"CHEBI:13193"},{"database":"ChEBI","id":"CHEBI:16007"},{"database":"ChEBI","id":"CHEBI:17499"},{"database":"ChEBI","id":"CHEBI:42266"},{"database":"ChEBI","id":"CHEBI:231886"}],"evidences":[{"evidenceCode":"ECO:0000269","source":"PubMed","id":"32855335"}]},"physiologicalReactions":[{"directionType":"left-to-right","reactionCrossReference":{"database":"Rhea","id":"RHEA:81436"},"evidences":[{"evidenceCode":"ECO:0000269","source":"PubMed","id":"32855335"}]}]},{"commentType":"CATALYTIC ACTIVITY","reaction":{"name":"2-(methylsulfanyl)ethanol + AH2 = ethene + methanethiol + A + H2O","reactionCrossReferences":[{"database":"Rhea","id":"RHEA:81439"},{"database":"ChEBI","id":"CHEBI:13193"},{"database":"ChEBI","id":"CHEBI:15377"},{"database":"ChEBI","id":"CHEBI:16007"},{"database":"ChEBI","id":"CHEBI:17499"},{"database":"ChEBI","id":"CHEBI:18153"},{"database":"ChEBI","id":"CHEBI:63861"}],"evidences":[{"evidenceCode":"ECO:0000269","source":"PubMed","id":"32855335"}]},"physiologicalReactions":[{"directionType":"left-to-right","reactionCrossReference":{"database":"Rhea","id":"RHEA:81440"},"evidences":[{"evidenceCode":"ECO:0000269","source":"PubMed","id":"32855335"}]}]},{"commentType":"COFACTOR","cofactors":[{"name":"iron-sulfur cluster","evidences":[{"evidenceCode":"ECO:0000305"}],"cofactorCrossReference":{"database":"ChEBI","id":"CHEBI:30408"}}]},{"texts":[{"evidences":[{"evidenceCode":"ECO:0000305","source":"PubMed","id":"32855335"}],"value":"The methylthio-alkane reductase is composed of three subunits, MarD, MarK and MarH"}],"commentType":"SUBUNIT"},{"texts":[{"evidences":[{"evidenceCode":"ECO:0000269","source":"PubMed","id":"32855335"}],"value":"Expression is up-regulated by the transcriptional regulator SalR when sulfate becomes limiting"}],"commentType":"INDUCTION"},{"texts":[{"evidences":[{"evidenceCode":"ECO:0000269","source":"PubMed","id":"32855335"}],"value":"Deletion of marBHDK gene cluster renders R.rubrum incapable of growth or production of ethylene above basal levels with MT-EtOH as the sole sulfur source (PubMed:32855335). The mutant cannot produce methanethiol or methionine (PubMed:32855335)"}],"commentType":"DISRUPTION PHENOTYPE"},{"texts":[{"evidences":[{"evidenceCode":"ECO:0000305"}],"value":"Belongs to the MarK family"}],"commentType":"SIMILARITY"}],"features":[{"type":"Chain","location":{"start":{"value":1,"modifier":"EXACT"},"end":{"value":466,"modifier":"EXACT"}},"description":"Methylthio-alkane reductase catalytic subunit beta","featureId":"PRO_0000463581"},{"type":"Region","location":{"start":{"value":1,"modifier":"EXACT"},"end":{"value":22,"modifier":"EXACT"}},"description":"Disordered","evidences":[{"evidenceCode":"ECO:0000256","source":"SAM","id":"MobiDB-lite"}]}],"keywords":[{"id":"KW-0002","category":"Technical term","name":"3D-structure"},{"id":"KW-0408","category":"Ligand","name":"Iron"},{"id":"KW-0411","category":"Ligand","name":"Iron-sulfur"},{"id":"KW-0479","category":"Ligand","name":"Metal-binding"},{"id":"KW-0560","category":"Molecular function","name":"Oxidoreductase"},{"id":"KW-1185","category":"Technical term","name":"Reference proteome"}],"references":[{"referenceNumber":1,"citation":{"id":"21886856","citationType":"journal article","authors":["Munk A.C.","Copeland A.","Lucas S.","Lapidus A.","Del Rio T.G.","Barry K.","Detter J.C.","Hammon N.","Israni S.","Pitluck S.","Brettin T.","Bruce D.","Han C.","Tapia R.","Gilna P.","Schmutz J.","Larimer F.","Land M.","Kyrpides N.C.","Mavromatis K.","Richardson P.","Rohde M.","Goeker M.","Klenk H.P.","Zhang Y.","Roberts G.P.","Reslewic S.","Schwartz D.C."],"citationCrossReferences":[{"database":"PubMed","id":"21886856"},{"database":"DOI","id":"10.4056/sigs.1804360"}],"title":"Complete genome sequence of Rhodospirillum rubrum type strain (S1).","publicationDate":"2011","journal":"Stand. 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