Regulatory phosphorylation of plant phosphoenolpyruvate carboxylase: role of a conserved basic residue upstream of the phosphorylation site

FEBS Letters

Izui, Katsura¹  Hata, Shingo¹  Ueno, Yoshihisa¹ 

[1] Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-01, Japan

关键词: Phosphoenolpyruvate carboxylase;    Regulatory phosphorylation;    Site-directed mutagenesis;    Protein kinase;    Zea mays;    CDPK;    calcium-dependent/calmodulin-independent protein kinase;    DTT;    dithiothreitol;    I 0.5;    the concentration of inhibitor required for 50% inhibition;    PEPC;    phosphoenolpyruvate carboxylase;    PK;    protein kinase;    PK-A;    cyclic AMP-dependent protein kinase;    PMSF;    phenylmethylsulfonyl fluoride;    K12N and S15D;    mutant maize PEPCs in which Lys-12 and Ser-15 are replaced by Asn and Asp;    respectively;    WT;    wild-type maize C4-form PEPC;   

DOI  :  10.1016/S0014-5793(97)01254-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

In order to mimic regulatory phosphorylation of the Ser-15 of maize C₄-form phosphoenolpyruvate carboxylase (PEPC), we replaced Ser-15 and Lys-12 with Asp (S15D) and Asn (K12N), respectively, by site-directed mutagenesis. Although both mutant enzymes were catalytically as active as the wild-type PEPC, they showed much less sensitivity to malate, an allosteric inhibitor, similarly to the phosphorylated wild-type PEPC. A maize protein kinase of 30 kDa which is known to be specific to PEPC (PEPC-PK), phosphorylated K12N as well as the wild-type PEPC but not S15D. The phosphorylation of K12N further diminished the sensitivity to malate. Thus, a positive charge of the conserved Lys-12 is not required for the recognition by PEPC-PK but contributes to the intrinsic sensitivity to malate inhibition.

【 授权许可】

Unknown