Absence of capsule reveals glycan-mediated binding and recognition of salivary mucin MUC7 by Streptococcus pneumoniae.
Absence of capsule reveals glycan-mediated binding and recognition of salivary mucin MUC7 by Streptococcus pneumoniae.
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DOI：
10.1111/omi.12113
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发表时间：
2016-04
影响因子：
3.7
通讯作者：
Ruhl S
中科院分区：
文献类型：
--
作者：
Thamadilok S;Roche-Håkansson H;Håkansson AP;Ruhl S
唾液蛋白调节口腔中的细菌定植，并与通过口咽的全身性病原体相互作用。一个有趣的例子是机会性呼吸道病原体肺炎链球菌，它通常存在于鼻咽部，但属于链球菌的更大缓解组，其中大多数定植在口腔中。S.肺炎链球菌还表达富含丝氨酸重复序列（SRR）的粘附素PsrP，其是与口腔缓解症组SRR粘附素（如S.pneumoniae的Hsa）的同源物。gordonii和S.吸血鬼由于后者通过识别末端唾液酸与唾液糖蛋白结合，我们想确定S。肺炎链球菌也可能通过相同的机制与唾液蛋白结合。我们发现，只有一个无荚膜突变体的S。肺炎链球菌TIGR4与唾液蛋白结合，最显著的是与粘蛋白MUC7结合，但是这种结合不是通过PsrP或唾液酸的识别介导的。然而，我们还发现，PsrP参与人红细胞（RBC）的凝集。去除PsrP后，发现了一种额外的先前被掩盖的凝集素样粘附素活性，介导唾液酸酶处理的RBC的凝集。使用定制的斑点糖蛋白和新糖蛋白斑点印迹阵列，我们确定了PsrP和推定的S。肺炎球菌粘附素可能负责肺炎球菌与唾液MUC7和RBC上的糖蛋白的结合。
Salivary proteins modulate bacterial colonization in the oral cavity and interact with systemic pathogens that pass through the oropharynx. An interesting example is the opportunistic respiratory pathogen Streptococcus pneumoniae that normally resides in the nasopharynx, but belongs to the greater Mitis group of streptococci, most of which colonize the oral cavity. S. pneumoniae also expresses a serine-rich repeat (SRR) adhesin, PsrP, that is a homologue to oral Mitis group SRR adhesins, such as Hsa of S. gordonii and SrpA of S. sanguinis. Since the latter bind to salivary glycoproteins through recognition of terminal sialic acids, we wanted to determine whether S. pneumoniae also binds to salivary proteins through possibly the same mechanism. We found that only a capsule-free mutant of S. pneumoniae TIGR4 binds to salivary proteins, most prominently to mucin MUC7, but that this binding was not mediated through PsrP or recognition of sialic acid. We also found, however, that PsrP is involved in agglutination of human red blood cells (RBCs). After removal of PsrP, an additional previously masked lectin-like adhesin activity mediating agglutination of sialidase-treated RBCs becomes revealed. Using a custom-spotted glycoprotein and neoglycoprotein dot blot array, we identify candidate glycan motifs recognized by PsrP and by the putative S. pneumoniae adhesin that could perhaps be responsible for pneumococcal binding to salivary MUC7 and glycoproteins on RBCs.