2aev
From Proteopedia
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'''MJ0158, NaBH4-reduced form''' | '''MJ0158, NaBH4-reduced form''' | ||
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[[Category: Rother, M.]] | [[Category: Rother, M.]] | ||
[[Category: Wahl, M C.]] | [[Category: Wahl, M C.]] | ||
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| - | [[Category: | + | [[Category: Plp]] |
| - | [[Category: | + | [[Category: Pyridoxal phosphate]] |
| - | [[Category: | + | [[Category: Selenocysteine synthase]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 18:57:42 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 15:57, 3 May 2008
MJ0158, NaBH4-reduced form
Overview
Bacterial selenocysteine synthase converts seryl-tRNA(Sec) to selenocysteinyl-tRNA(Sec) for selenoprotein biosynthesis. The identity of this enzyme in archaea and eukaryotes is unknown. On the basis of sequence similarity, a conserved open reading frame has been annotated as a selenocysteine synthase gene in archaeal genomes. We have determined the crystal structure of the corresponding protein from Methanococcus jannaschii, MJ0158. The protein was found to be dimeric with a distinctive domain arrangement and an exposed active site, built from residues of the large domain of one protomer alone. The shape of the dimer is reminiscent of a substructure of the decameric Escherichia coli selenocysteine synthase seen in electron microscopic projections. However, biochemical analyses demonstrated that MJ0158 lacked affinity for E. coli seryl-tRNA(Sec) or M. jannaschii seryl-tRNA(Sec), and neither substrate was directly converted to selenocysteinyl-tRNA(Sec) by MJ0158 when supplied with selenophosphate. We then tested a hypothetical M. jannaschii O-phosphoseryl-tRNA(Sec) kinase and demonstrated that the enzyme converts seryl-tRNA(Sec) to O-phosphoseryl-tRNA(Sec) that could constitute an activated intermediate for selenocysteinyl-tRNA(Sec) production. MJ0158 also failed to convert O-phosphoseryl-tRNA(Sec) to selenocysteinyl-tRNA(Sec). In contrast, both archaeal and bacterial seryl-tRNA synthetases were able to charge both archaeal and bacterial tRNA(Sec) with serine, and E. coli selenocysteine synthase converted both types of seryl-tRNA(Sec) to selenocysteinyl-tRNA(Sec). These findings demonstrate that a number of factors from the selenoprotein biosynthesis machineries are cross-reactive between the bacterial and the archaeal systems but that MJ0158 either does not encode a selenocysteine synthase or requires additional factors for activity.
About this Structure
2AEV is a Single protein structure of sequence from Methanocaldococcus jannaschii. Full crystallographic information is available from OCA.
Reference
Structural and functional investigation of a putative archaeal selenocysteine synthase., Kaiser JT, Gromadski K, Rother M, Engelhardt H, Rodnina MV, Wahl MC, Biochemistry. 2005 Oct 11;44(40):13315-27. PMID:16201757 Page seeded by OCA on Sat May 3 18:57:42 2008
