Abstract |
In Archaea selenocysteine (Sec) is synthesized in three steps. First seryl-tRNA synthetase acylates tRNA(Sec) with serine to generate Ser- tRNA(Sec). Then phosphoseryl- tRNA(Sec) kinase (PSTK) forms Sep- tRNA(Sec) , which is converted to Sec-tRNA(Sec) by Sep- tRNA:Sec- tRNA synthase (SepSecS) in the presence of selenophosphate produced by selenophosphate synthetase (SelD). A complete in vivo analysis of the archaeal Sec biosynthesis pathway is still unavailable, and the existence of a redundant pathway or of a rescue mechanism based on the conversion of Sep- tRNA(Sec) to Cys- tRNA(Sec) during selenium starvation, cannot be excluded. Here we present a mutational analysis of Sec biosynthesis in Methanococcus maripaludis strain Mm900. Sec formation is abolished upon individually deleting the genes encoding SelD, PSTK or SepSecS; the resulting mutant strains could no longer grow on formate while growth with H(2) + CO(2) remained unaffected. However, deletion of the PSTK and SepSecS genes was not possible unless the selenium-free [NiFe]-hydrogenases Frc and Vhc were expressed. This required the prior deletion of either the gene encoding SelD or that of HrsM, a LysR-type regulator suppressing transcription of the frc and vhc operons in the presence of selenium. These results show that M. maripaludis Mm900 is facultatively selenium-dependent with a single pathway of Sec-tRNA(Sec) formation.
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Authors | Michael J Hohn, Sotiria Palioura, Dan Su, Jing Yuan, Dieter Söll |
Journal | Molecular microbiology
(Mol Microbiol)
Vol. 81
Issue 1
Pg. 249-58
(Jul 2011)
ISSN: 1365-2958 [Electronic] England |
PMID | 21564332
(Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, U.S. Gov't, Non-P.H.S.)
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Copyright | © 2011 Blackwell Publishing Ltd. |
Chemical References |
- Archaeal Proteins
- Formates
- RNA, Transfer, Amino Acid-Specific
- tRNA, selenocysteine-
- Selenocysteine
- formic acid
- Carbon Dioxide
- Hydrogen
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Topics |
- Archaeal Proteins
(genetics, metabolism)
- Biosynthetic Pathways
(genetics)
- Carbon Dioxide
(metabolism)
- Formates
(metabolism)
- Gene Deletion
- Hydrogen
(metabolism)
- Methanococcus
(genetics, growth & development, metabolism)
- RNA, Transfer, Amino Acid-Specific
(metabolism)
- Selenocysteine
(biosynthesis)
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