Seryl‐phosphorylation of soybean nodule sucrose synthase (nodulin‐100) by a Ca2+‐dependent protein kinase

FEBS Letters

Chollet, Raymond¹  Zhang, Xiu-Qing¹ 

[1] Department of Biochemistry, University of Nebraska-Lincoln, George W. Beadle Center, Lincoln, NE 68588-0664, USA

关键词: Nodulin-100;    Protein kinase;    Protein phosphorylation;    Root nodule;    Soybean (Glycine max);    Sucrose synthase;    CDPK;    Ca2+-dependent protein kinase;    E-64;    trans-epoxysuccinyl-l-leucylamido-(4-guanidino)butane;    FPLC;    fast-protein liquid chromatography;    MC-LR;    microcystin-LR;    PEG;    polyethylene glycol;    PEP;    phosphoenolpyruvate;    PEPC;    PEP carboxylase;    PEPC-K;    PEPC-kinase;    PMSF;    phenylmethylsulfonyl fluoride;    SS;    sucrose synthase;    SS-K;    SS-kinase;    TLE;    thin-layer electrophoresis;    W-7;    N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide;   

DOI  :  10.1016/S0014-5793(97)00537-1

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Sucrose synthase (SS; EC 2.4.1.13) was radiolabeled in situ by incubating detached soybean nodules with ³²Pi. Phosphoamino acid analysis indicated that SS was phosphorylated on a serine residue(s). In-vitro phosphorylation of purified nodule SS by desalted nodule extracts was Ca²⁺-dependent. This SS-kinase was partially purified (∼2200-fold) from nodules harvested from illuminated plants. The molecular mass of the SS-kinase was about 55 000 on a Superdex 75 size-exclusion column or in a denaturing autophosphorylation gel. With either purified nodule SS or Syntide 2 as substrate, exogenous calmodulin and phosphatidylserine showed little or no effect on the in-vitro activity of this partially purified protein kinase. However, its activity was inhibited by W-7. The purified nodule SS-kinase (or CDPK) phosphorylated nodule PEP carboxylase (PEPC; EC 4.1.1.31) in the presence of Ca²⁺. In contrast, a partially purified nodule PEPC-kinase preparation was incapable of phosphorylating nodule SS. Unlike nodule PEPC [Zhang et al. (1995) Plant Physiol. 108, 1561–1568], the phosphorylation state of SS is not likely modulated in planta by photosynthate supply from the shoots.

【 授权许可】

Unknown