酵母的Shu蛋白復合物,，是由Shu1、Shu2,、Psy3和Csm2幾種蛋白組成，它通過偶聯(lián)復制后修復與同源重組,，維持了基因組的穩(wěn)定性,。
然而，由于缺乏對Shu蛋白的生化及結構信息,，它們在該通路中精確的作用還不明確,。近日，中國科學技術大學滕脈坤課題組解析了Psy3-Csm2復合體在1.9 埃分辨率的晶體結構,。
晶體結構表明,，Psy3與Csm2主要通過一個疏水核心形成了一個異二聚體,。出乎預料的是，Psy3和Csm2都有一個相似的非常類似于Rad51的ATPase核心結構域,。
Psy3和Csm2的L2環(huán)與Rad51的結構非常類似,，它賦予了Shu復合體DNA結合活性。與Rad51一樣,，Shu復合體似乎通過非特異性的結合到DNA上,，形成了一個核蛋白纖絲 。
基于結構突變研究表明了Shu復合體的DNA結合活性,，而且這對修復甲磺酸甲酯引起的DNA損傷是必須的,。該發(fā)現(xiàn)對研究Shu復合體介導的Srs2的調節(jié)奠定了很好的基礎。相關論文發(fā)表在3月30日的The journal of Biological Chemistry,。
滕脈坤教授是中國科學技術大學生命科學學院黨總支書記兼副院長,。多年從事生物大分子晶體學和結構生物學研究，曾從事DNA寡聚核苷酸及其DNA-藥物復合物的晶體學,；病毒晶體學,；T-細胞受體及其復合物的晶體學；葡萄糖異構酶蛋白質工程等研究工作,。目前主要進行真核生物轉錄調控,、基因損傷修復、囊泡形成相關蛋白質及其復合物的結構與功能關系研究,，同時關注天然蛇毒毒素蛋白對各類離子通道的調控機理研究,。（生物谷Deepblue編譯）
doi: 10.1074/jbc.M111.334698
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Structural analysis of Shu proteins reveals a DNA-binding role essential for resisting damage
Yuyong Tao, Xu Li, Yiwei Liu, Jianbin Ruan, Shali Qi, Liwen Niu and Maikun Teng.
The yeast Shu complex, consisting of the proteins Shu1, Shu2, Psy3 and Csm2, maintains genomic stability by coupling post-replication repair to homologous recombination.However, a lack of biochemical and structural information on the Shu proteins precludes revealing their precise roles within the pathway. Here we report the 1.9 A crystal structure of the Psy3-Csm2 complex.The crystal structure shows that Psy3 forms a heterodimer with Csm2 mainly through a hydrophobic core. Unexpectedly, Psy3 and Csm2 share a similar architecture which closely resembles the ATPase core domain of Rad51.The L2 loop present in Psy3 and Csm2 is similar to that of Rad51, and confers the DNA-binding activity of the Shu complex. As with Rad51, the Shu complex appears to form a nucleoprotein filament by binding non-specifically to DNA.Structure-based mutagenesis studies have demonstrated that the DNA-binding activity of the Shu complex is essential for repair of the methyl methanesulfonate-induced DNA damage. Our findings provide good foundations for the understanding of the Srs2 regulation by the Shu complex.
