Functional similarities of a thermostable protein-disulfide oxidoreductase identified in the archaeon Pyrococcus horikoshii to bacterial DsbA enzymes

• Published in: Extremophiles : life under extreme conditions 2007-01, Vol.11 (1), p.85-94
• Main Authors: Kuroita, Toshihiro, Kanno, Takuya, Kawai, Atsushi, Kawakami, Bunsei, Oka, Masanori, Endo, Yaeta, Tozawa, Yuzuru
• Format: Article
• Language: English
• Subjects: Amino Acid Motifs; Amino Acid Sequence; Amino acids; Archaea; Archaeal Proteins - chemistry; Archaeal Proteins - genetics; Archaeal Proteins - metabolism; Bacteria; Bacterial Proteins - chemistry; Bacterial Proteins - metabolism; Bacteriology; Biological and medical sciences; Cloning, Molecular; Conserved Sequence; Databases, Protein; DsbA; E coli; Enzyme Stability; Escherichia coli; Fundamental and applied biological sciences. Psychology; Metabolism. Enzymes; Microbiology; Molecular Sequence Data; Mutation; Peptides; Protein Disulfide Reductase (Glutathione) - chemistry; Protein Disulfide Reductase (Glutathione) - genetics; Protein Disulfide Reductase (Glutathione) - metabolism; Protein Disulfide-Isomerases - chemistry; Protein Disulfide-Isomerases - metabolism; Protein Sorting Signals; Protein-disulfide oxidoreductase; Pyrococcus horikoshii; Pyrococcus horikoshii - enzymology; Pyrococcus horikoshii - genetics; Recombinant Proteins - metabolism; Sequence Alignment; Sequence Analysis, Protein; Space life sciences; Temperature
• ISSN: 1431-0651; 1433-4909
• DOI: 10.1007/s00792-006-0015-4

We have isolated and characterized a gene for a putative protein-disulfide oxidoreductase (phdsb) in the archaeon Pyrococcus horikoshii. The open reading frame of phdsb encodes a protein of 170 amino acids with an NH₂-terminal extension similar to the bacterial signal peptides. The putative mature region of PhDsb includes a sequence motif, Cys-Pro-His-Cys (CPHC), that is conserved in members of the bacterial DsbA family, but otherwise the archaeal and bacterial sequences do not show substantial similarity. A recombinant protein corresponding to the predicted mature form of PhDsb behaved as a monomer and manifested oxidoreductase activities in vitro similar to those of DsbA of Escherichia coli. The catalytic activity of PhDsb was thermostable and was shown by mutation analysis to depend on the NH₂-terminal cysteine residue of the CPHC motif. Thus, in spite of their low overall sequence similarities, DsbA-like proteins of archaea and bacteria appear to be highly similar in terms of function.