title: Inactivation of the selB gene in Methanococcus maripaludis: effect on synthesis of selenoproteins and their sulfur-containing homologs.
abstract: The genome of Methanococcus maripaludis harbors genes for at least six selenocysteine-containing proteins and also for homologs that contain a cysteine codon in the position of the UGA selenocysteine codon. To investigate the synthesis and function of both the Se and the S forms, a mutant with an inactivated selB gene was constructed and analyzed. The mutant was unable to synthesize any of the selenoproteins, thus proving that the gene product is the archaeal translation factor (aSelB) specialized for selenocysteine insertion. The wild-type form of M. maripaludis repressed the synthesis of the S forms of selenoproteins, i.e., the selenium-independent alternative system, in selenium-enriched medium, but the mutant did not. We concluded that free selenium is not involved in regulation but rather a successional compound such as selenocysteyl-tRNA or some selenoprotein. Apart from the S forms, several enzymes from the general methanogenic route were affected by selenium supplementation of the wild type or by the selB mutation. Although the growth of M. maripaludis on H(2)/CO(2) is only marginally affected by the selB lesion, the gene is indispensable for growth on formate because M. maripaludis possesses only a selenocysteine-containing formate dehydrogenase.
authors.affiliation: Microbiology, Department of Biology I, University of Munich, Maria-Ward-Strasse 1a, D-80638 Munich, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Rother
authors.forename: Isabella
authors.initials: I
authors.lastname: Mathes
authors.forename: Friedrich
authors.initials: F
authors.lastname: Lottspeich
authors.forename: August
authors.initials: A
authors.lastname: Böck
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000235:genetics* / Q000378:metabolism*; D005560:Formate Dehydrogenases / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D017017:Methanococcus / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D008969:Molecular Sequence Data; D010445:Peptide Elongation Factors / Q000235:genetics* / Q000378:metabolism; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D017279:Selenocysteine / Q000737:chemistry / Q000378:metabolism; D051140:Selenoproteins; D013455:Sulfur / Q000737:chemistry / Q000378:metabolism
chemical_list: D019843:Archaeal Proteins; D010445:Peptide Elongation Factors; D011506:Proteins; D051140:Selenoproteins; D017279:Selenocysteine; D013455:Sulfur; D005560:Formate Dehydrogenases