BgaA acts as an adhesin to mediate attachment of some pneumococcal strains to human epithelial cells.
BgaA acts as an adhesin to mediate attachment of some pneumococcal strains to human epithelial cells.
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DOI：
10.1099/mic.0.045609-0
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发表时间：
2011-08
期刊：
影响因子：
--
通讯作者：
King SJ
中科院分区：
文献类型：
--
作者：
Limoli DH;Sladek JA;Fuller LA;Singh AK;King SJ
肺炎链球菌在呼吸道的定植是肺炎球菌疾病的重要先兆。为了有效地定殖，细菌必须粘附在上皮细胞表面。S.肺炎克雷伯氏菌具有表面相关的外切糖苷酶，其能够顺序地使人聚糖去糖基化。两种外切糖苷酶，神经氨酸酶（NanA）和β-半乳糖苷酶（BgaA），以前已被证明有助于S。肺炎链球菌与人上皮细胞的粘附，因为这些基因中的任一个的缺失导致粘附降低。已经表明，这些酶可以通过切割糖以揭示宿主细胞上的受体来调节粘附。用外源性神经氨酸酶预处理上皮细胞可恢复nanA突变体的粘附，而用β-半乳糖苷酶预处理不能恢复bgaA突变体的粘附。这些数据表明，BgaA可能不起作用，揭示一个受体，并暗示BgaA在坚持的替代作用。在这里，我们证明了β-半乳糖苷酶活性不是BgaA介导的粘附所必需的。此外，重组BgaA（rBgaA）的粘附试验和预处理的上皮细胞与rBgaA都显着降低了亲株的粘附水平，但不是BgaA突变体。这些数据的一个可能的解释是，BgaA是作为一个粘附素和rBgaA是结合到受体，防止细菌结合。一个珠结合试验表明，BgaA可以直接结合到人类上皮细胞，支持的假设，BgaA是一种粘附素。上皮细胞受体的初步表征表明它是鞘糖脂背景下的聚糖。为了进一步建立这种粘附机制的相关性，我们证明了BgaA介导的粘附有助于最近的临床分离株粘附到原代人上皮细胞。总之，这些数据表明BgaA作为粘附素的新作用，并表明这种机制可能有助于体内至少一些肺炎球菌菌株的粘附。
Streptococcus pneumoniae colonization of the respiratory tract is an essential precursor for pneumococcal disease. To colonize efficiently, bacteria must adhere to the epithelial-cell surface. S. pneumoniae possesses surface-associated exoglycosidases that are capable of sequentially deglycosylating human glycans. Two exoglycosidases, neuraminidase (NanA) and β-galactosidase (BgaA), have previously been shown to contribute to S. pneumoniae adherence to human epithelial cells, as deletion of either of these genes results in reduced adherence. It has been suggested that these enzymes may modulate adherence by cleaving sugars to reveal a receptor on host cells. Pretreatment of epithelial cells with exogenous neuraminidase restores the adherence of a nanA mutant, whereas pretreatment with β-galactosidase does not restore the adherence of a bgaA mutant. These data suggest that BgaA may not function to reveal a receptor, and implicate an alternative role for BgaA in adherence. Here we demonstrate that β-galactosidase activity is not required for BgaA-mediated adherence. Addition of recombinant BgaA (rBgaA) to adherence assays and pretreatment of epithelial cells with rBgaA both significantly reduced the level of adherence of the parental strain, but not the BgaA mutant. One possible explanation of these data is that BgaA is acting as an adhesin and that rBgaA is binding to the receptor, preventing bacterial binding. A bead-binding assay demonstrated that BgaA can bind directly to human epithelial cells, supporting the hypothesis that BgaA is an adhesin. Preliminary characterization of the epithelial-cell receptor suggests that it is a glycan in the context of a glycosphingolipid. To further establish the relevance of this adherence mechanism, we demonstrated that BgaA-mediated adherence contributed to adherence of a recent clinical isolate to primary human epithelial cells. Together, these data suggest a novel role for BgaA as an adhesin and suggest that this mechanism could contribute to adherence of at least some pneumococcal strains in vivo.
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影响因子：
3.2
作者：
Bagnoli, Fabio;Moschioni, Monica;Barocchi, Michele A.
通讯作者：
Barocchi, Michele A.
影响因子：
4.8
作者：
CLARKE, VA;PLATT, N;BUTTERS, TD
通讯作者：
BUTTERS, TD
影响因子：
3.1
作者：
DeBentzmann, S;Roger, P;Puchelle, E
通讯作者：
Puchelle, E
影响因子：
6.4
作者：
Gould, JM;Weiser, JN
通讯作者：
Weiser, JN
DOI：
10.1016/s0006-291x(88)81222-1
发表时间：
1988-05-31
影响因子：
3.1
作者：
BADER, DE;RING, M;HUBER, RE
通讯作者：
HUBER, RE