Department of Chemistry, University of California, Riverside, California 92521-0403, United States.
J Proteome Res. 2013 Sep 6;12(9):4167-75. doi: 10.1021/pr400498y. Epub 2013 Aug 26.
The eukaryotic centromere is an essential chromatin region required for accurate segregation of sister chromatids during cell division. Centromere protein B (CENP-B) is a highly conserved protein which can bind to the 17-bp CENP-B box on the centromeric DNA. In this study, we found that CENP-B could be α-N-methylated in human cells. We also showed that the level of the α-N-methylation was stimulated in cells in response to a variety of extracellular stimuli, including increased cell density, heat shock, and arsenite treatment, although the methylation level was not altered upon metaphase arrest. We identified N-terminal RCC1 methyltransferase (NRMT) as a major enzyme required for the CENP-B methylation. Additionally, we found that chromatin-bound CENP-B was primarily trimethylated and α-N-trimethylation could enhance CENP-B's binding to CENP-B box in cells. Our study also expands the function of protein α-N-methylation that has been known for decades and whose function remains largely unexplored.
真核生物着丝粒是一种必需的染色质区域，对于细胞分裂过程中姐妹染色单体的准确分离至关重要。着丝粒蛋白 B（CENP-B）是一种高度保守的蛋白质，能够与着丝粒 DNA 上的 17 个碱基对的 CENP-B 盒结合。在这项研究中，我们发现 CENP-B 可以在人细胞中发生 α-N-甲基化。我们还表明，细胞对各种细胞外刺激的反应会刺激 α-N-甲基化水平的升高，包括细胞密度增加、热休克和亚砷酸盐处理，尽管在中期停滞时甲基化水平没有改变。我们确定 N 端 RCC1 甲基转移酶（NRMT）是 CENP-B 甲基化所必需的主要酶。此外，我们发现染色质结合的 CENP-B 主要是三甲基化的，α-N-三甲基化可以增强 CENP-B 在细胞中与 CENP-B 盒的结合。我们的研究还扩展了蛋白质 α-N-甲基化的功能，这种功能已经存在了几十年，但功能在很大程度上仍未得到探索。
