State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, The Joint International Research Laboratory of Metabolic & Developmental Sciences, Shanghai Jiao Tong University, 200240, Shanghai, China.
State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 200237, Shanghai, China.
Nat Commun. 2018 Nov 8;9(1):4689. doi: 10.1038/s41467-018-07093-1.
There have been very few reports on protein domains that specifically recognize sulfur. Here we present the crystal structure of the sulfur-binding domain (SBD) from the DNA phosphorothioation (PT)-dependent restriction endonuclease ScoMcrA. SBD contains a hydrophobic surface cavity that is formed by the aromatic ring of Y164, the pyrolidine ring of P165, and the non-polar side chains of four other residues that serve as lid, base, and wall of the cavity. The SBD and PT-DNA undergo conformational changes upon binding. The SRGRR loop inserts into the DNA major groove to make contacts with the bases of the GGCC core sequence. Mutating key residues of SBD impairs PT-DNA association. More than 1000 sequenced microbial species from fourteen phyla contain SBD homologs. We show that three of these homologs bind PT-DNA in vitro and restrict PT-DNA gene transfer in vivo. These results show that SBD-like PT-DNA readers exist widely in prokaryotes.
目前关于专门识别硫的蛋白质结构域的报道非常少。在这里，我们展示了来自 DNA 硫代磷酸化（PT）依赖性限制内切酶 ScoMcrA 的硫结合结构域（SBD）的晶体结构。SBD 包含一个疏水性表面腔，由 Y164 的芳环、P165 的吡咯烷环以及其他四个充当腔盖、腔底和腔壁的非极性侧链组成。SBD 和 PT-DNA 在结合时会发生构象变化。SRGRR 环插入 DNA 大沟，与 GGCC 核心序列的碱基形成接触。突变 SBD 的关键残基会损害 PT-DNA 的结合。来自十四个门的 1000 多种已测序微生物物种含有 SBD 同源物。我们表明，其中三个同源物在体外结合 PT-DNA，并在体内限制 PT-DNA 基因转移。这些结果表明，SBD 样的 PT-DNA 读取器在原核生物中广泛存在。
