P1, P3‐bis(5′‐adenosyl)triphosphate (Ap3A) as a substrate and a product of mammalian tryptophanyl‐tRNA synthetase

FEBS Letters

Kovaleva, Galina¹  Merkulova, Tatyana¹  Kisselev, Lev¹ 

[1] Engelhardt Institute of Molecular Biology, The Russian Academy of Sciences, 32, Vavilova, 117984 Moscow B-334, Russian Federation

关键词: Aminoacyl-tRNA synthetase;    Tryptophanyl-tRNA synthetase;    Ap4A/Ap3A synthesis;    aaRS;    aminoacyl-tRNA synthetases (EC 6.1.1);    Ap3A;    P1;    P3-bis(5′-adenosyl)triphosphate;    Ap4A;    P1;    P4-bis(5′-adenosyl)tetraphosphate;    ATPase;    adenosine triphosphatase;    E(Trp ∼ AMP);    tryptophanyl adenylate—enzyme complex;    E(–Zn);    Zn2+-deprived enzyme;    PEI-cellulose;    polyethylene imino cellulose;    TrpRS;    tryptophanyl-tRNA synthetase (EC 6.1.1.2);   

DOI  :  10.1016/0014-5793(94)00764-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Bovine tryptophanyl-tRNA synthetase (TrpRS, E.C. 6.1.1.2) is unable to catalyze in vitro formation of Ap₄A in contrast to some other aminoacyl-tRNA synthetases. However, in the presence of l-tryptophan, ATP-Mg²⁺ and ADP the enzyme catalyzes the Ap₃A synthesis via adenylate intermediate. Ap₃A (not Ap₄A) may serve as a substrate for TrpRS in the reaction of E·(Trp ∼ AMP) formation and in the tRNA^Trp charging. The K _m value for Ap₃A was higher than the K _m for ATP (approx. 1.00 vs. 0.22 mM) and V _max was 3 times lower than for ATP. The Zn²⁺-deficient enzyme catalyzes Ap₃A synthesis in the absence of exogenous ADP due to ATPase activity of Zn²⁺-deprived TrpRS. The inability of mammalian TrpRS to synthesize Ap₄A, might be considered as a molecular tool preventing the removal of Zn²⁺ due to chelation by Ap₄A and therefore preserving the enzyme activity.

【 授权许可】

Unknown