Kafková Lucie, Debler Erik W, Fisk John C, Jain Kanishk, Clarke Steven G, Read Laurie K
From the Department of Microbiology and Immunology, Witebsky Center for Microbial Pathogenesis and Immunology, and Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14214.
the Laboratory of Cell Biology, The Rockefeller University, New York, New York 10065, and.
J Biol Chem. 2017 Feb 10;292(6):2089-2100. doi: 10.1074/jbc.M116.757112. Epub 2016 Dec 20.
Prozymes are catalytically inactive enzyme paralogs that dramatically stimulate the function of weakly active enzymes through complex formation. The two prozymes described to date reside in the polyamine biosynthesis pathway of the human parasite , an early branching eukaryote that lacks transcriptional regulation and regulates its proteome through posttranscriptional and posttranslational means. Arginine methylation is a common posttranslational modification in eukaryotes catalyzed by protein arginine methyltransferases (PRMTs) that are typically thought to function as homodimers. We demonstrate that a major PRMT, PRMT1, functions as a heterotetrameric enzyme-prozyme pair. The inactive PRMT paralog, PRMT1, is essential for catalytic activity of the PRMT1 subunit. Mutational analysis definitively demonstrates that TbPRMT1 is the cofactor-binding subunit and carries all catalytic activity of the complex. Our results are the first demonstration of an obligate heteromeric PRMT, and they suggest that enzyme-prozyme organization is expanded in trypanosomes as a posttranslational means of enzyme regulation.
酶原是催化无活性的酶旁系同源物，通过形成复合物极大地刺激弱活性酶的功能。迄今为止描述的两种酶原存在于人类寄生虫的多胺生物合成途径中，这种早期分支的真核生物缺乏转录调控，通过转录后和翻译后手段调节其蛋白质组。精氨酸甲基化是真核生物中一种常见的翻译后修饰，由通常被认为以同二聚体形式发挥作用的蛋白质精氨酸甲基转移酶（PRMTs）催化。我们证明，一种主要的PRMT，即PRMT1，作为一种异源四聚体酶 - 酶原对发挥作用。无活性的PRMT旁系同源物PRMT1对于PRMT1亚基的催化活性至关重要。突变分析明确表明，TbPRMT1是辅因子结合亚基，并具有该复合物的所有催化活性。我们的结果首次证明了一种专性异源多聚体PRMT，并且表明在锥虫中酶 - 酶原组织作为酶调节的翻译后手段得到了扩展。
