Kalhor H R, Niewmierzycka A, Faull K F, Yao X, Grade S, Clarke S, Rubenstein P A
Department of Chemistry, University of California, Los Angeles, California, 90095, USA.
Arch Biochem Biophys. 1999 Oct 1;370(1):105-11. doi: 10.1006/abbi.1999.1370.
To identify a protein histidine methyltransferase from Saccharomyces cerevisiae, we examined purified actin for the presence of the highly conserved 3-methylhistidine residue at position 73 by amino acid analysis of the whole protein and by amino acid analysis and mass spectrometry of the corresponding tryptic fragment. Surprisingly, we found that His-73 is not modified. A similar lack of modification was also found in actin from the yeast Candida albicans, while rabbit muscle actin revealed the expected 3-methylhistidine residue. Phylogenetic analysis of actin sequences suggests that this modification was introduced in evolution after the divergence of yeast from higher eukaryotic organisms, including unicellular eukaryotes such as Acanthamoeba, Dictyostelium, and Physarum, whose actins contain 3-methylhistidine. Our methodology for the analytical determination of 3-methylhistidine in actin offers an improved approach for investigating histidine methylation in proteins.
为了从酿酒酵母中鉴定一种蛋白质组氨酸甲基转移酶，我们通过对整个蛋白质进行氨基酸分析以及对相应胰蛋白酶片段进行氨基酸分析和质谱分析，来检测纯化的肌动蛋白中第73位是否存在高度保守的3 - 甲基组氨酸残基。令人惊讶的是，我们发现第73位的组氨酸未被修饰。在白色念珠菌的肌动蛋白中也发现了类似的未修饰情况，而兔肌肉肌动蛋白则显示出预期的3 - 甲基组氨酸残基。肌动蛋白序列的系统发育分析表明，这种修饰是在酵母与包括单细胞真核生物如棘阿米巴、盘基网柄菌和绒泡菌在内的高等真核生物分化之后在进化过程中引入的，这些生物的肌动蛋白含有3 - 甲基组氨酸。我们用于分析测定肌动蛋白中3 - 甲基组氨酸的方法为研究蛋白质中的组氨酸甲基化提供了一种改进的方法。
