ATP-dependent aggregation of single-stranded DNA by a bacterial SMC homodimer
ATP-dependent aggregation of single-stranded DNA by a bacterial SMC homodimer
复制标题
DOI：
10.1093/emboj/17.23.7139
复制
发表时间：
1998-12-01
期刊：
影响因子：
11.4
通讯作者：
Hirano, T
中科院分区：
文献类型：
--
作者：
Hirano, M;Hirano, T
SMC(S)是细菌、古生菌和真核生物中高度保守的ATPase，参与一系列的染色体动力学过程，包括染色体凝聚、剂量补偿和重组修复。在真核生物中，两种不同的SMC蛋白形成一个异二聚体，而异二聚体又是一个大的蛋白质复合体的核心成分。尽管最近取得了进展，但在单个SMC亚基中还没有发现ATP依赖的活性。我们首次报道了枯草芽孢杆菌的一种细菌SMC蛋白的生化特征。与真核细胞不同，枯草杆菌SMC蛋白(BsSMC)是一种简单的同源二聚体，没有相关的亚基。它优先与单链DNA结合，并具有受单链DNA刺激的ATPase活性。在ATP存在的情况下，BsSMC以单链DNA特异的方式形成大的核蛋白聚集体。当BsSMC与三磷酸腺苷和单链DNA结合时，其蛋白水解性裂解发生改变。单链DNA的能量依赖聚集可能代表了细菌染色体分离过程中发生的一种原始类型的染色体凝聚。
SMC ((s) under bar tructural (m) under bar aintenance of (c) under bar hromosomes) proteins are putative ATPases that are highly conserved among Bacteria, Archaea and Eucarya, Eukaryotic SMC proteins are implicated in a diverse range of chromosome dynamics including chromosome condensation, dosage compensation and recombinational repair. In eukaryotes, two different SMC proteins form a heterodimer, which in turn acts as the core component of a large protein complex. Despite recent progress, no ATP-dependent activity has been found in individual SMC subunits. We report here the first biochemical characterization of a bacterial SMC protein from Bacillus subtilis. Unlike eukaryotic versions, the B. subtilis SMC protein (BsSMC) is a simple homodimer with no associated subunits. It binds preferentially to single-stranded DNA (ssDNA) and has a ssDNA-stimulated ATPase activity. In the presence of ATP, BsSMC forms large nucleoprotein aggregates in a ssDNA-specific manner. Proteolytic cleavage of BsSMC is changed upon binding to ATP and ssDNA. The energy-dependent aggregation of ssDNA might represent a primitive type of chromosome condensation that occurs during segregation of bacterial chromosomes.