苜蓿中华根瘤菌matB基因的克隆及其功能的研究

Cloning and Functional Analysis of matB Gene in Sinorhizobium meliloti

通过同源性分析,发现苜蓿中华根瘤菌(Sinorhizobium meliloti)菌株Rm1021中matB基因与三叶草生物型豌豆根瘤菌(Rhizobium leguminosarum bv.trifolii)和慢生型大豆根瘤菌(Bradyrhizobium japonicum USDA110)中编码丙二酸单酰辅酶A合成酶(malonyl-CoA synthetase)基因在氨基酸水平上分别达到了75%和67%一致性,具有高度同源性。因此,从Rm1021中克隆出matB基因,并在大肠埃希菌(Escherichia coli)中进行体外诱导表达和纯化。纯化的MatB蛋白具有丙二酸单酰辅酶A合成酶的活性,测定的Km值是710μmol,Vmax是0.209μmol/min/mg。

Based on the analysis of amino acids homology, we found that matB gene in Sinorhizobium meliloti Rml021 show highly homology with the malonyl-CoA synthetase of the Rhizobium leguminosarum by. trifolii and the Bradyrhizobium japonicttm USDA 110. The MatB protein shares 75% and 67% indentity with malonyl-CoA synthetase of the R. leguminosarum by. trifolii and the B. japonicurn USDA I I0, respectively. So we cloned matB gene, constructed the matB recombinant plasmid and purified it from E. coll. We found that the purified MatB have the activity of malonyl-CoA synthetase, showing that its Kin value is 710 μmol and Vmax is 0. 209 μxmol/min/mg.