2AEV

MJ0158, NaBH4-reduced form

Summary for 2AEV

• Entry DOI: 10.2210/pdb2aev/pdb
• Related: 2AEV
• Descriptor: Hypothetical protein MJ0158, SULFATE ION (3 entities in total)
• Functional Keywords: selenocysteine synthase, plp, pyridoxal phosphate, homo-oligomerization, unknown function
• Biological source: Methanocaldococcus jannaschii
• Total number of polymer chains: 1
• Total formula weight: 43035.44

Authors

Kaiser, J.T.,Gromadski, K.,Rother, M.,Engelhardt, H.,Rodnina, M.V.,Wahl, M.C. (deposition date: 2005-07-24, release date: 2005-10-04, Last modification date: 2023-11-15)

Primary citation

Kaiser, J.T.,Gromadski, K.,Rother, M.,Engelhardt, H.,Rodnina, M.V.,Wahl, M.C.
Structural and functional investigation of a putative archaeal selenocysteine synthase
Biochemistry, 44:13315-13327, 2005

PubMed Abstract: 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.

PubMed: 16201757
DOI: 10.1021/bi051110r

Experimental method

X-RAY DIFFRACTION (2 Å)