A new family of bacterial condensins.
A new family of bacterial condensins.
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细菌凝缩蛋白的新家族。
DOI：
10.1111/j.1365-2958.2011.07763.x
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发表时间：
2011
影响因子：
3.6
通讯作者：
Rybenkov,ValentinV
中科院分区：
文献类型：
--
作者：
Petrushenko,ZoyaM;She,Weifeng;Rybenkov,ValentinV
凝缩蛋白在整体染色质组织中发挥着核心作用。在细菌中，已鉴定出两个凝缩蛋白家族：MukBEF 和 SMC-ScpAB 复合物。在给定物种中通常只发现这两种复合物中的一种，从而产生了一种范例，即单个凝缩蛋白组织细菌染色体。通过序列分析，我们鉴定了第三个凝缩蛋白家族 MksBEF（类 MukBEF SMC 蛋白），它广泛存在于多种细菌中。这些蛋白质似乎与 MukBEF 关系较远，具有相似的操纵子组织和相似的预测二级结构，尽管卷曲螺旋明显较短。 MksBEF 的所有三个亚基都表现出显着的序列变异，并且可以分为一系列重叠的亚家族。 MksBEF 通常与 SMC-ScpAB、MukBEF 共存，有时还与其他 MksBEF 共存。在铜绿假单胞菌中，SMC 和 MksB 都有助于忠实的染色体分配，它们的失活导致无核细胞频率增加。此外，MksBEF 可以补充 SMC 缺陷细胞中的无核细胞形成。纯化的 PaMksB 显示出缩合蛋白的典型活性，包括 ATP 调节的 DNA 结合和缩合。值得注意的是，MksB 的 DNA 结合受到 ATP 的负向调节，这使其与其他已知的 SMC 蛋白不同。因此，几种特殊的凝缩蛋白可能参与细菌染色体的组织。
Condensins play a central role in global chromatin organization. In bacteria, two families of condensins have been identified, the MukBEF and SMC–ScpAB complexes. Only one of the two complexes is usually found in a given species, giving rise to a paradigm that a single condensin organizes bacterial chromosomes. Using sequence analysis, we identified a third family of condensins, MksBEF (MukBEF‐like SMC proteins), which is broadly present in diverse bacteria. The proteins appear distantly related to MukBEF, have a similar operon organization and similar predicted secondary structures albeit with notably shorter coiled‐coils. All three subunits of MksBEF exhibit significant sequence variation and can be divided into a series of overlapping subfamilies. MksBEF often coexists with the SMC–ScpAB, MukBEF and, sometimes, other MksBEFs. InPseudomonas aeruginosa, both SMC and MksB contribute to faithful chromosome partitioning, with their inactivation leading to increased frequencies of anucleate cells. Moreover, MksBEF can complement anucleate cell formation in SMC‐deficient cells. Purified PaMksB showed activities typical for condensins including ATP‐modulated DNA binding and condensation. Notably, DNA binding by MksB is negatively regulated by ATP, which sets it apart from other known SMC proteins. Thus, several specialized condensins might be involved in organization of bacterial chromosomes.