两性绵霉线粒体中存在丙酮酸激酶?另一种丙酮酸激酶基因(pyk2)的克隆及序列分析

Does There Exist a Pyruvate Kinase in Mitochondria of Achlya bisexualis? Cloning and Sequencing for the Another Type of Gene Encoding for Pyruvate Kinase

在藻状菌纲两性绵霉 (Achlyabisexualis)的cDNA文库中筛选并克隆了另外一种类型的丙酮酸激酶基因pyk2 ,完成了这种基因的全序列测定 .将这种这种基因编码的丙酮酸激酶PYK2与前文报道的两性绵霉丙酮酸激酶PYK1氨基酸序列进行比较 ,显示二者有 4 0 8%同源性 .用PSORTII计算机程序分析表明 ,与存在于细胞质中的PYK1不同 ,PYK2的N端带有线粒体的导肽序列 ,因而可能位于线粒体中 .结合有关光合生物硅藻一些糖酵解酶位于线粒体的报道 ,认为不论是光合还是非光合的原生生物的线粒体中都可能存在有糖酵解酶 .

Pyruvate kinase is an enzyme to catalyze phosphoenolpyruvate to pyruvate in glycolytic pathway which is generally localized in the cytosol of eukaryotic cell. Here, the second type gene ( pvy 2) encoding for the another kind of pyruvate kinase (PVY2) in oomycetes Achlya bisexualis , a nonphotosynthetic protist with the heterokont flagelliflory, was cloned and sequenced. The amino acid sequence deduced from the cDNA also share about 44.8% of identity with the amino acid sequence of the another pyruvate kinase (PVY1) for Achlya bisexualis reported previously. On the basis of analysis from PSORTⅡon line computer program, the PYK2 was identified to be localized in mitochondria rather than in cytosol like PVY1. Furthermore, it was found that the PVY2 possess the presequence for mitochondrial targeting signal. These results support that one segment of glycolytic pathway in some heterokont flagellated protists may occur in mitochondria in both photosynthetic and non photosynthetic organisms.