PDBsum entry 2aev

Unknown function

PDB id: 2aev

Contents

Protein chain

366 a.a. *

Ligands

SO4 ×9

Waters ×180

* Residue conservation analysis

PDB id:

2aev

Name:

Unknown function

Title:

Mj0158, nabh4-reduced form

Structure:

Hypothetical protein mj0158. Chain: a. Engineered: yes

Source:

Methanocaldococcus jannaschii. Organism_taxid: 2190. Gene: mj0158. Expressed in: escherichia coli. Expression_system_taxid: 562.

Biol. unit:

Dimer (from PDB file)

Resolution:

2.00Å R-factor: 0.225 R-free: 0.271

Authors:

J.T.Kaiser,K.Gromadski,M.Rother,H.Engelhardt,M.V.Rodnina,M.C.Wahl

Key ref:

J.T.Kaiser et al. (2005). Structural and functional investigation of a putative archaeal selenocysteine synthase. Biochemistry, 44, 13315-13327. PubMed id: 16201757 DOI: 10.1021/bi051110r

Date:

24-Jul-05 Release date: 04-Oct-05

Protein chain

Q57622  (Y158_METJA) -  UPF0425 pyridoxal phosphate-dependent protein MJ0158 from Methanocaldococcus jannaschii (strain ATCC 43067 / DSM 2661 / JAL-1 / JCM 10045 / NBRC 100440)

Seq: 374 a.a.

Struc: 366 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

DOI no: 10.1021/bi051110r

Biochemistry 44:13315-13327 (2005)

PubMed id: 16201757

Structural and functional investigation of a putative archaeal selenocysteine synthase.

J.T.Kaiser, K.Gromadski, M.Rother, H.Engelhardt, M.V.Rodnina, M.C.Wahl.

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.