两种细菌复制解旋酶加载器的趋同进化。
Convergent evolution in two bacterial replicative helicase loaders.
机构信息
Department of Chemistry and Biochemistry, City College of New York, New York, NY 10031, USA; PhD Program in Biochemistry, The Graduate Center of the City University of New York, New York, NY 10016, USA.
Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA.
出版信息
Trends Biochem Sci. 2022 Jul;47(7):620-630. doi: 10.1016/j.tibs.2022.02.005. Epub 2022 Mar 26.
Dedicated loader proteins play essential roles in bacterial DNA replication by opening ring-shaped DnaB-family helicases and chaperoning single-stranded (ss)DNA into a central motor chamber as a prelude to DNA unwinding. Although unrelated in sequence, the Escherichia coli DnaC and bacteriophage λ P loaders feature a similar overall architecture: a globular domain linked to an extended lasso/grappling hook element, located at their N and C termini, respectively. Both loaders remodel a closed DnaB ring into nearly identical right-handed open conformations. The sole element shared by the loaders is a single alpha helix, which binds to the same site on the helicase. Physical features of the loaders establish that DnaC and λ P evolved independently to converge, through molecular mimicry, on a common helicase-opening mechanism.
专用加载蛋白通过打开环形 DnaB 家族解旋酶并将单链 (ss)DNA 引导到中央动力室，为 DNA 解旋做准备，从而在细菌 DNA 复制中发挥重要作用。尽管大肠杆菌 DnaC 和噬菌体 λ P 加载器在序列上没有关系，但它们具有相似的整体结构：一个球形结构域与一个延伸的套索/抓钩元件相连，分别位于它们的 N 端和 C 端。这两种加载器都将封闭的 DnaB 环重塑为几乎相同的右手开放式构象。加载器唯一共享的元件是一个单一的α螺旋，它与解旋酶的相同位点结合。加载器的物理特征表明，DnaC 和 λ P 是通过分子模拟独立进化而来的，它们采用了相同的解旋酶开启机制。
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