近日，瑞士洛桑大学(UNIL) Stephan Gruber课题组提出，parS着丝粒能够通过ParB水解酶进行自组织。该项研究成果发表在10月25日出版的《科学》杂志上。

课题组表明，ParB是一种可以将胞苷三磷酸（CTP）水解为二磷酸（CDP）的酶。parS DNA通过ParB和CTP水解刺激CTP的结合。核苷酸冷冻电镜结构阐明了二聚化依赖性ParB CTP酶的催化中心。单分子成像和生化分析概述了parB存在但CTP不存在的情况下parB从parS扩散的特征。

这些发结果表明着丝粒通过在parS处自动装载ParB DNA滑动夹来组装。ParB CTP酶与已知的核苷酸水解酶无关，可能是开发新型抗生素的有望靶标。

ParABS系统促进细菌和古生菌中染色体分离和质粒分区。ParB蛋白结合着丝粒的parS DNA序列并扩散到两侧DNA上。

附：英文原文

Title: Self-organization of parS centromeres by the ParB CTP hydrolase

Author: Young-Min Soh, Iain Finley Davidson, Stefano Zamuner, Jérme Basquin, Florian Patrick Bock, Michael Taschner, Jan-Willem Veening, Paolo De Los Rios, Jan-Michael Peters, Stephan Gruber

Issue&Volume: 2019/10/24

Abstract: ParABS systems facilitate chromosome segregation and plasmid partitioning in bacteria and archaea. ParB protein binds centromeric parS DNA sequences and spreads to flanking DNA. We show that ParB is an enzyme that hydrolyzes cytidine triphosphate (CTP) to diphosphate (CDP). parS DNA stimulates cooperative CTP binding by ParB and CTP hydrolysis. A nucleotide co-crystal structure elucidates the catalytic center of the dimerization-dependent ParB CTPase. Single-molecule imaging and biochemical assays recapitulate features of ParB spreading from parS in the presence but not absence of CTP. The findings suggest that centromeres assemble by self-loading of ParB DNA sliding clamps at parS. ParB CTPase is not related to known nucleotide hydrolases and might be a promising target for developing new classes of antibiotics.

DOI: 10.1126/science.aay3965

Source: https://science.sciencemag.org/content/early/2019/10/23/science.aay3965