Comparative Study of Bacterial SPOR Domains Identifies Functionally Important Differences in Glycan Binding Affinity.
Comparative Study of Bacterial SPOR Domains Identifies Functionally Important Differences in Glycan Binding Affinity.
复制标题
细菌 SPOR 结构域的比较研究确定了聚糖结合亲和力的重要功能差异。
DOI：
10.1128/jb.00252-22
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发表时间：
2022
影响因子：
3.2
通讯作者：
Weiss,DavidS
中科院分区：
文献类型：
--
作者：
Yahashiri,Atsushi;Kaus,GabrielaM;Popham,DavidL;Houtman,JonCD;Weiss,DavidS
细菌SPOR结构域通过在细胞壁酰胺酶去除了茎肽的位点结合隔肽聚糖（PG）将蛋白质靶向分裂体。这些PG结构被称为裸露聚糖。尽管所有表征的SPOR结构域都结合裸露的聚糖，但亲和力是否存在差异尚不清楚。在这里，我们使用等温滴定量热法（ITC），以确定相对PG聚糖结合亲和力（Kd）的四个大肠杆菌SPOR结构域和一个嗜纤维菌SPOR结构域。结果表明，E. coliDamXSPOR和C. hutchinsoniiCHU2221SPOR对E. coli FtsNSPOR.为了研究PG结合亲和力的这些差异是否对SPOR结构域蛋白功能很重要，我们构建并表征了一组DamX和FtsN“交换”蛋白。正如预期的那样，所有SPOR结构域交换蛋白定位于分裂位点，并且在FtsN的情况下，所有异源SPOR结构域支持细胞分裂。然而，对于DamX，只有来自CHU2221的高亲和力SPOR结构域支持细胞分裂中的正常功能。总之，不同的SPOR结构域以不同的亲和力结合裸露的PG聚糖，这似乎对一些SPOR结构域蛋白的功能很重要（例如，DamX），但不用于其他功能（例如，IMPORTANCESPOR结构域蛋白是多种细菌中细胞分裂装置的主要组分。SPOR结构域的主要功能是将蛋白质靶向到分裂位点，其通过结合到间隔肽聚糖来实现。然而，SPOR结构域是否具有除隔靶向之外的任何功能尚不清楚。在这里，我们发现SPOR结构域在它们的PG结合亲和力上是不同的，至少在E.大肠杆菌细胞分裂蛋白DamX，具有高亲和力的SPOR结构域有助于适当的功能。
Bacterial SPOR domains target proteins to the divisome by binding septal peptidoglycan (PG) at sites where cell wall amidases have removed stem peptides. These PG structures are referred to as denuded glycans. Although all characterized SPOR domains bind denuded glycans, whether there are differences in affinity is not known. Here, we use isothermal titration calorimetry (ITC) to determine the relative PG glycan binding affinity (Kd) of four Escherichia coli SPOR domains and one Cytophaga hutchinsonii SPOR domain. We found that theKdvalues ranged from approximately 1 μM for E. coli DamXSPORandC. hutchinsoniiCHU2221SPORto about 10 μM for E. coli FtsNSPOR. To investigate whether these differences in PG binding affinity are important for SPOR domain protein function, we constructed and characterized a set of DamX and FtsN “swap” proteins. As expected, all SPOR domain swap proteins localized to the division site, and, in the case of FtsN, all of the heterologous SPOR domains supported cell division. However, for DamX, only the high-affinity SPOR domain from CHU2221 supported normal function in cell division. In summary, different SPOR domains bind denuded PG glycans with different affinities, which appears to be important for the functions of some SPOR domain proteins (e.g., DamX) but not for the functions of others (e.g., FtsN).IMPORTANCESPOR domain proteins are prominent components of the cell division apparatus in a wide variety of bacteria. The primary function of SPOR domains is targeting proteins to the division site, which they accomplish by binding to septal peptidoglycan. However, whether SPOR domains have any functions beyond septal targeting is unknown. Here, we show that SPOR domains vary in their PG binding affinities and that, at least in the case of the E. coli cell division protein DamX, having a high-affinity SPOR domain contributes to proper function.