Rahman M U, Hudson A P
Department of Microbiology and Immunology, Medical College of Pennsylvania, Philadelphia.
Biochem Biophys Res Commun. 1995 Jan 17;206(2):756-63. doi: 10.1006/bbrc.1995.1107.
We have shown that mitochondrial (mt) transcription in yeast (S. cerevisiae) is governed in part by cAMP via a mt cAMP-dependent protein kinase (cAPK), and that the BCY1 gene product acts as regulatory subunit for that organellar enzyme, as it does for cytoplasmic cAPK. Here we assess mt cAPK activity and mt transcription in mutants for the TPK1, TPK2, and TPK3 genes, which encode catalytic subunits of cytoplasmic cAPK. Protein extracts from purified mitochondria from each of the three possible double TPK mutants show mt cAMP-dependent protein phosphorylation. Relative mt transcript levels in these mutants, however, suggest that TPK2 functions less well than does TPK1 or TPK3 in organellar transcriptional control. Thus, both mt and cytoplasmic cAPKs employ the same species of regulatory and catalytic proteins, and versions of the enzyme having various combinations of catalytic species function differentially in cAMP-dependent mt transcriptional control.
我们已经表明，酵母（酿酒酵母）中的线粒体（mt）转录部分受cAMP通过线粒体cAMP依赖性蛋白激酶（cAPK）调控，并且BCY1基因产物作为该细胞器酶的调节亚基，就像它对细胞质cAPK所起的作用一样。在这里，我们评估了TPK1、TPK2和TPK3基因（编码细胞质cAPK的催化亚基）突变体中的线粒体cAPK活性和线粒体转录。来自三种可能的双TPK突变体中每种突变体的纯化线粒体的蛋白质提取物显示出线粒体cAMP依赖性蛋白磷酸化。然而，这些突变体中的相对线粒体转录水平表明，在细胞器转录控制中，TPK2的功能不如TPK1或TPK3。因此，线粒体和细胞质cAPK都使用相同种类的调节和催化蛋白，并且具有不同催化种类组合的酶变体在cAMP依赖性线粒体转录控制中发挥不同的作用。
