PDBsum entry 1fvg

Oxidoreductase

PDB id: 1fvg

Contents

Protein chain

192 a.a. *

Ligands

DTT

Waters ×140

* Residue conservation analysis

References listed in PDB file

Key reference

Title

Structure and mechanism of peptide methionine sulfoxide reductase, An "anti-Oxidation" enzyme.

Authors

W.T.Lowther, N.Brot, H.Weissbach, B.W.Matthews.

Ref.

Biochemistry, 2000, 39, 13307-13312. [DOI no: 10.1021/bi0020269]

PubMed id

11063566

Abstract

Peptide methionine sulfoxide reductase (MsrA) reverses oxidative damage to both free methionine and methionine within proteins. As such, it helps protect the host organism against stochastic damage that can contribute to cell death. The structure of bovine MsrA has been determined in two different modifications, both of which provide different insights into the biology of the protein. There are three cysteine residues located in the vicinity of the active site. Conformational changes in a glycine-rich C-terminal tail appear to allow all three thiols to come together and to participate in catalysis. The structures support a unique, thiol-disulfide exchange mechanism that relies upon an essential cysteine as a nucleophile and additional conserved residues that interact with the oxygen atom of the sulfoxide moiety.

Secondary reference #1

Title

Thiol-Disulfide exchange is involved in the catalytic mechanism of peptide methionine sulfoxide reductase.

Authors

W.T.Lowther, N.Brot, H.Weissbach, J.F.Honek, B.W.Matthews.

Ref.

Proc Natl Acad Sci U S A, 2000, 97, 6463-6468. [DOI no: 10.1073/pnas.97.12.6463]

PubMed id

10841552

Figure 1.
Fig. 1. Sequence alignment of MsrAs and proteins containing putative MsrA domains. The longer N-terminal sequences preceding the region of strong homology are not shown. Filled squares mark those sequences that have been truncated at the C terminus. The locations of the cysteine residues of bMsrA are indicated by filled circles. The alignment was generated by using the CLUSTAL W algorithm in MACVECTOR 6.0 (Oxford Molecular Group). Dark and light background shading illustrate regions having greater than 51% identity or similarity, respectively. Spaces added for insertions are shown by dashed lines. The sequence of Neisseria gonorrhoeae (NEIGO) MsrA was redetermined (see text) and the region corresponding to Cys-72 in bMsrA was found to be G205GCFWGLEAYFQRIDGVVDAVSG227, which differs from that determined previously (A^205AASGAWGAWKPISNASTAWLTRYR226) (22). The remainder of the sequence within the MsrA domain was unchanged. Abbreviations: ARATH, Arabidopsis thaliana (accession number, P54150); BACSU, Bacillus subtilis (P54154); BOVIN, Bos taurus (P54149); BRANA, Brassica napus (P54151); DROME, Drosophila melanogaster (P08761); ERWCH, Erwinia chrysanthemi (AJ012716); FRAAN, Fragaria ananassa (P54152); GRACI, Gracilaria gracilis (AAD43253); HAEIN, Haemophilus influenzae (P45213); ECOLI, Escherichia coli (P27110); HELPY, Helicobacter pylori (O25011); HUMAN, Homo sapiens (CAB59628); LYCES, Lycopersicon esculentum (P54153); MYCGE, Mycoplasma genitalium (P47648); MYCPN, Mycoplasma pneumoniae (P75188); MYTB, Mycobacterium tuberculosis (CAB07043); NEIGO, Neisseria gonorrhoeae (P14930); SCHIPO, Schizosaccharomyces pombe (Q09859); STRPN, Streptococcus pneumoniae (P35593); YEAST, Saccharomyces cerevisiae (P40029).

Figure 3.
Fig. 3. Proposed reaction mechanism for MsrA catalysis. Protonation of Met(O) (I) leads to the formation of a sulfonium ion (II). Possibly concomitant with sulfoxide protonation, Cys-72 attacks the sulfur atom of the sulfonium ion, leading to the formation of a covalent intermediate (III). Breakdown of the complex is facilitated by proton transfer and the attack on Cys-72 by Cys-218 (IV). Return of the active site to a fully reduced state (I) is facilitated by thiol disulfide exchange via Cys-227 (V) and either DTT or a thioredoxin regeneration system (VI) (see Discussion for details). Abbreviations: TR, thioredoxin; TRR, thioredoxin reductase.