Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA.
Pediatric Dentistry and Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA.
Infect Immun. 2018 Jun 21;86(7). doi: 10.1128/IAI.00146-18. Print 2018 Jul.
The high-resolution structure of glucan binding protein C (GbpC) at 1.14 Å, a sucrose-dependent virulence factor of the dental caries pathogen , has been determined. GbpC shares not only structural similarities with the V regions of AgI/II and SspB but also functional adherence to salivary agglutinin (SAG) and its scavenger receptor cysteine-rich domains (SRCRs). This is not only a newly identified function for GbpC but also an additional fail-safe binding mechanism for Despite the structural similarities with antigen I/II (AgI/II) and SspB of , GbpC remains unique among these surface proteins in its propensity to adhere to dextran/glucans. The complex crystal structure of GbpC with dextrose (β-d-glucose; Protein Data Bank ligand BGC) highlights exclusive structural features that facilitate this interaction with dextran. Targeted deletion mutant studies on GbpC's divergent loop region in the vicinity of a highly conserved calcium binding site confirm its role in biofilm formation. Finally, we present a model for adherence to dextran. The structure of GbpC highlights how artfully microbes have engineered the lectin-like folds to broaden their functional adherence repertoire.
已解析出 1.14 Å 分辨率的葡聚糖结合蛋白 C（GbpC）结构，该蛋白是龋齿病原菌的蔗糖依赖性毒力因子。GbpC 不仅与 AgI/II 和 SspB 的 V 区具有结构相似性，还具有与唾液黏附素（SAG）及其清道夫受体富含半胱氨酸结构域（SRCRs）的功能黏附性。这不仅是 GbpC 的新发现功能，也是 表面蛋白的另一种附加的可靠结合机制。尽管 GbpC 与 的 AgI/II（AgI/II）和 SspB 具有结构相似性，但与这些表面蛋白相比，它仍具有独特的葡聚糖亲和力。GbpC 与右旋糖（β-d-葡萄糖；蛋白数据库配体 BGC）的复合物晶体结构突出了促进与右旋糖相互作用的独特结构特征。在高度保守的钙结合位点附近的 GbpC 发散环区域进行的靶向缺失突变研究证实了其在生物膜形成中的作用。最后，我们提出了一种针对葡聚糖黏附的模型。GbpC 的结构突出了微生物如何巧妙地设计凝集素样折叠以拓宽其功能黏附谱。
