Nuclear magnetic resonance solution structure of the peptidoglycan-binding SPOR domain from Escherichia coli DamX: insights into septal localization.
Nuclear magnetic resonance solution structure of the peptidoglycan-binding SPOR domain from Escherichia coli DamX: insights into septal localization.
复制标题
大肠杆菌 DamX 肽聚糖结合 SPOR 结构域的核磁共振溶液结构：对隔膜定位的见解。
DOI：
10.1021/bi301609e
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发表时间：
2013
期刊：
影响因子：
2.9
通讯作者：
Weiss,DavidS
中科院分区：
文献类型：
--
作者：
Williams,KyleB;Yahashiri,Atsushi;Arends,SJRyan;Popham,DavidL;Fowler,CAndrew;Weiss,DavidS
Spor结构域存在于数以千计的细菌蛋白中，可能与隔膜肽聚糖(PG)结合，但Spor-PG相互作用的细节尚未阐明。在这里，我们描述了一种名为DamX的大肠杆菌分裂蛋白Spor结构域的结构和功能。核磁共振显示，该结构域由四链反平行的β-折叠组成，一侧由两个α-螺旋支撑。第三个螺旋，命名为α3，与β-Sheet的另一个面相关联，但这个螺旋相对可移动。定点突变揭示了与β3相互作用的α-Sheet的表面对于隔膜的定位和与PG球囊的结合是重要的。α3的位置和移动性提示它可能调节PG结合，但尽管α3缺失突变体仍定位于隔环，但它们太不稳定，不能用于PG结合实验。最后，为了评估Spor结构域在DamX函数中的重要性，我们构造并刻画了E。产生带有Spor结构域点突变或Spor结构域缺失的DamX蛋白的共突变株。这些研究表明，Spor结构域对与DamX相关的多种活动非常重要：将蛋白质靶向分裂位点，对胆盐脱氧胆酸盐产生完全抵抗，当DamX产生正常水平时提高细胞分裂效率，当DamX过度产生时抑制细胞分裂。
SPOR domains are present in thousands of bacterial proteins and probably bind septal peptidoglycan (PG), but the details of the SPOR–PG interaction have yet to be elucidated. Here we characterize the structure and function of the SPOR domain for anEscherichia colidivision protein named DamX. Nuclear magnetic resonance revealed the domain comprises a four-stranded antiparallel β-sheet buttressed on one side by two α-helices. A third helix, designated α3, associates with the other face of the β-sheet, but this helix is relatively mobile. Site-directed mutagenesis revealed the face of the β-sheet that interacts with α3 is important for septal localization and binding to PG sacculi. The position and mobility of α3 suggest it might regulate PG binding, but although α3 deletion mutants still localized to the septal ring, they were too unstable to use in a PG binding assay. Finally, to assess the importance of the SPOR domain in DamX function, we constructed and characterizedE. colimutants that produced DamX proteins with SPOR domain point mutations or SPOR domain deletions. These studies revealed the SPOR domain is important for multiple activities associated with DamX: targeting the protein to the division site, conferring full resistance to the bile salt deoxycholate, improving the efficiency of cell division when DamX is produced at normal levels, and inhibiting cell division when DamX is overproduced.