Identification of a Novel Streptococcal Adhesin P (SadP) Protein Recognizing Galactosyl-α1-4-galactose-containing Glycoconjugates CONVERGENT EVOLUTION OF BACTERIAL PATHOGENS TO BINDING OF THE SAME HOST RECEPTOR
Identification of a Novel Streptococcal Adhesin P (SadP) Protein Recognizing Galactosyl-α1-4-galactose-containing Glycoconjugates CONVERGENT EVOLUTION OF BACTERIAL PATHOGENS TO BINDING OF THE SAME HOST RECEPTOR
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DOI：
10.1074/jbc.m111.260992
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发表时间：
2011-11-11
影响因子：
4.8
通讯作者：
Finne, Jukka
中科院分区：
文献类型：
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作者：
Kouki, Annika;Haataja, Sauli;Finne, Jukka
细菌粘附通常是感染的先决条件，宿主细胞表面碳水化合物作为粘附受体发挥主要作用。链球菌是感染性疾病的主要原因。然而，只有少数碳水化合物特异性链球菌粘附素是已知的。猪链球菌是一种重要的猪病原体，也是引起猪和人类脑膜炎的人畜共患病原体。在这项研究中，我们已经确定了一个粘附素介导的结合S。猪与含半乳糖基-α 1 - 4-半乳糖（Gal α 1 - 4Gal）的宿主受体结合。功能未知的S。猪细胞壁蛋白（SSU0253），在此命名为SadP（链球菌粘附素P），使用含Gal α 1 - 4Gal的亲和基质和LC-ESI质谱法鉴定。虽然该蛋白的功能以前并不清楚，但最近在蛋白质组学研究中将其鉴定为免疫原性细胞壁蛋白。sadP基因的插入失活消除了S.猪Gal α 1 - 4Gal依赖性结合。克隆粘附素基因sadP，并在大肠杆菌中表达。其结合特异性的表征表明，SadP识别Gal α 1 - 4Gal-寡糖并结合其天然糖脂受体GbO（3）（CD77）。SadP的N端含有一个Gal α 1-Gal结合位点，与其他细菌粘附素，包括大肠杆菌粘附素没有明显的序列相似性。coli P菌毛粘附素，或E.大肠杆菌verotoxin或铜绿假单胞菌凝集素I也识别相同的Gal α 1 - 4Gal二糖。SadP和E.大肠杆菌P粘附素代表了一个独特的例子，趋同进化到结合到同一个主机受体结构。
Bacterial adhesion is often a prerequisite for infection, and host cell surface carbohydrates play a major role as adhesion receptors. Streptococci are a leading cause of infectious diseases. However, only few carbohydrate-specific streptococcal adhesins are known. Streptococcus suis is an important pig pathogen and a zoonotic agent causing meningitis in pigs and humans. In this study, we have identified an adhesin that mediates the binding of S. suis to galactosyl-alpha 1-4-galactose (Gal alpha 1-4Gal)-containing host receptors. A functionally unknown S. suis cell wall protein (SSU0253), designated here as SadP (streptococcal adhesin P), was identified using a Gal alpha 1-4Gal-containing affinity matrix and LC-ESI mass spectrometry. Although the function of the protein was not previously known, it was recently identified as an immunogenic cell wall protein in a proteomic study. Insertional inactivation of the sadP gene abolished S. suis Gal alpha 1-4Gal-dependent binding. The adhesin gene sadP was cloned and expressed in Escherichia coli. Characterization of its binding specificity showed that SadP recognizes Gal alpha 1-4Gal-oligosaccharides and binds its natural glycolipid receptor, GbO(3) (CD77). The N terminus of SadP was shown to contain a Gal alpha 1-Gal-binding site and not to have apparent sequence similarity to other bacterial adhesins, including the E. coli P fimbrial adhesins, or to E. coli verotoxin or Pseudomonas aeruginosa lectin I also recognizing the same Gal alpha 1-4Gal disaccharide. The SadP and E. coli P adhesins represent a unique example of convergent evolution toward binding to the same host receptor structure.