A novel O‐phospho‐L‐serine sulfhydrylation reaction catalyzed by O‐acetylserine sulfhydrylase from Aeropyrum pernix K1

FEBS Letters

Mino, Koshiki¹  Ishikawa, Kazuhiko¹ 

[1] The Special Division for Human Life Technology, National Institute of Advanced Industrial Science and Technology (AIST, Kansai), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan

关键词: O-Acetylserine sulfhydrylase;    L-Cysteine biosynthesis;    Archaeon;    O-Acetyl-L-serine;    O-Phospho-L-serine;    Aeropyrum pernix;    SAT;    serine acetyltransferase;    OASS;    O-acetylserine sulfhydrylase;    PLP;    pyridoxal 5′-phosphate;    ORF;    open reading frame;   

DOI  :  10.1016/S0014-5793(03)00913-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

O-Acetylserine sulfhydrylase (OASS), a pyridoxal 5′-phosphate (PLP)-dependent enzyme, catalyzes the synthesis of L-cysteine from O-acetyl-L-serine and sulfide. O-Acetyl-L-serine is labile at high temperatures at which hyperthermophilic archaea live. Herein, a study of the substrate specificity of OASS from Aeropyrum pernix K1 with respect to O-acetyl-L-serine in L-cysteine synthesis is described. L-Azaserine, 3-chloro-L-alanine, and O-phospho-L-serine reacted with A. pernix OASS in a PLP-dependent manner. Sulfhydrylation reactions using these substrates reached a maximum in the pH range between 7.3 and 8.1. L-Azaserine and O-phospho-L-serine were found to be heat-stable substrates. The presence of FeCl₃ or NiCl₂ strongly inhibited the O-acetyl-L-serine sulfhydrylation reaction, whereas the O-phospho-L-serine sulfhydrylation reaction was only slightly inhibited. Kinetic analyses revealed that the O-phospho-L-serine sulfhydrylation reaction as well as the O-acetyl-L-serine sulfhydrylation reaction for A. pernix OASS followed a ping-pong bi-bi mechanism. In the case of the O-phospho-L-serine sulfhydrylation reaction at 85°C, the K _m values for O-phospho-L-serine and sulfide, and the rate constant were 250 mM, 12.5 mM, and 14 000 s⁻¹, respectively. The reactivity of O-phospho-L-serine in the L-cysteine synthetic reaction provides a key for understanding the biosynthesis of L-cysteine by hyperthermophilic archaea. This is the first report of an enzyme that catalyzes the O-phospho-L-serine sulfhydrylation reaction.

【 授权许可】

Unknown