Ishige Kazuya, Zhang Haiyu, Kornberg Arthur
Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305-5307, USA.
Proc Natl Acad Sci U S A. 2002 Dec 24;99(26):16684-8. doi: 10.1073/pnas.262655299. Epub 2002 Dec 13.
An enzyme that uses inorganic polyphosphate (poly P) as a donor to convert GDP to GTP has been purified 1,300-fold to homogeneity from lysates of Pseudomonas aeruginosa PAOM5. Poly P chains of 30-50 residues are optimal; those of 15-700 residues can also serve. GDP is preferred over ADP among nucleoside diphosphate acceptors. This nucleoside diphosphate kinase (NDK) activity resides in the same protein isolated for its synthesis of poly P from GTP and designated PPK2 in an accompanying report. The reaction that synthesizes poly P and the reaction that utilizes poly P differ in their kinetic features. Especially notable is the catalytic potency of the NDK activity, which is 75-fold greater than that of poly P synthesis. PPK2 appears in the stationary phase of growth and reaches NDK levels of 5-10% that of the classic NDK; both kinase activities may figure in the generation of the guanosine precursors in the synthesis of alginate, an exopolysaccharide essential for the virulence of P. aeruginosa.
一种利用无机多聚磷酸盐（多聚P）作为供体将GDP转化为GTP的酶已从铜绿假单胞菌PAOM5的裂解物中纯化了1300倍，达到同质状态。30至50个残基的多聚P链是最优的；15至700个残基的多聚P链也可以起作用。在核苷二磷酸受体中，GDP比ADP更受青睐。这种核苷二磷酸激酶（NDK）活性存在于从GTP合成多聚P并在一篇相关报告中命名为PPK2的同一种蛋白质中。合成多聚P的反应和利用多聚P的反应在动力学特征上有所不同。特别值得注意的是NDK活性的催化效力，它比多聚P合成的催化效力高75倍。PPK2出现在生长的稳定期，达到经典NDK水平的5%至10%；这两种激酶活性可能都参与了藻酸盐合成中鸟苷前体的生成，藻酸盐是铜绿假单胞菌毒力所必需的一种胞外多糖。
