Thiocyanate hydrolase is a cobalt-containing metalloenzyme with a cysteine-sulfinic acid ligand.
Thiocyanate hydrolase (SCNase) purified from Thiobacillus thioparus THI115 hydrolyzes thiocyanate to carbonyl sulfide and ammonia. DNA sequences of the cloned genes revealed the close relation of SCNase to nitrile hydratase (NHase). The consensus sequences for coordination of the metal ion found in NHases were also conserved in the gamma subunit of SCNase. Here, we showed that the SCNase contained one cobalt atom per alphabetagamma heterotrimer. UV-vis absorption spectrum suggested that the cobalt exists as a non-corrin ion. Reduced SCNase showed an ESR signal characteristic of low-spin Co2+, which closely resembled that of the Co-type NHases. Mass spectrometry for the peptide fragment containing the metal-binding motif of the SCNase gamma subunit indicated that the cysteine residue at position 131 was post-translationally oxidized to a cysteine-sulfinic acid. From these results, we concluded that SCNases and NHases form a novel non-corrin and/or non-heme protein family having post-translationally modified cysteine ligands.
Katayama
Yoko
Y
Department of Environmental and Natural Resource Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan. katayama@cc.tuat.ac.jp
Hashimoto
Kanako
K
Nakayama
Hiroshi
H
Mino
Hiroyuki
H
Nojiri
Masaki
M
Ono
Taka-aki
TA
Nyunoya
Hiroshi
H
Yohda
Masafumi
M
Takio
Koji
K
Odaka
Masafumi
M
D000595:Amino Acid Sequence; D003035:Cobalt / Q000737:chemistry* / Q000378:metabolism; D003545:Cysteine / Q000737:chemistry* / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D006867:Hydrolases / Q000737:chemistry* / Q000378:metabolism; D008024:Ligands; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D013056:Spectrophotometry, Ultraviolet; D013441:Sulfinic Acids / Q000737:chemistry* / Q000378:metabolism; D013855:Thiobacillus / Q000201:enzymology
D008024:Ligands; D013441:Sulfinic Acids; D003035:Cobalt; D006867:Hydrolases; C074369:thiocyanate hydrolase; D003545:Cysteine