Commensal bacteria must colonize host mucosal surfaces to exert health-promoting properties, and bind to gastrointestinal tract (GIT) mucins via their cell surface adhesins. Considerable effort has been directed towards discovery of pathogen adhesins and their ligands to develop anti-infective strategies; however, little is known about the lectin-like adhesins and associated carbohydrate ligands in commensals. In this study, an in silico approach was used to detect surface exposed adhesins in the human commensal Lactobacillus paracasei subsp. paracasei, a promising probiotic commonly used in dairy product fermentation that presents anti-microbial activity. Of the 13 adhesin candidates, 3 sortase-dependent pili clusters were identified in this strain and expression of the adhesin candidate genes was confirmed in vitro. Mass spectrometry analysis confirmed the presence of surface adhesin elongation factor Tu and the chaperonin GroEL, but not pili expression. Whole cells were subsequently incubated on microarrays featuring a panel of GIT mucins from nine different mammalian species and two human-derived cell lines and a library of carbohydrate structures. Binding profiles were compared to those of two known pili-producing lactobacilli, L. johnsonii and L. rhamnosus and all Lactobacillus species displayed overlapping but distinct signatures, which may indicate different abilities for regiospecific GIT colonization. In addition, L. paracasei whole cells favoured binding to α-(2 → 3)-linked sialic acid and α-(1 → 2)-linked fucose-containing carbohydrate structures including blood groups A, B and O and Lewis antigens x, y and b. This study furthers our understanding of host-commensal cross-talk by identifying potential adhesins and specific GIT mucin and carbohydrate ligands and provides insight into the selection of colonization sites by commensals in the GIT.

中文翻译：

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使用计算机模拟和糖组学微阵列分析方法鉴定副干酪乳杆菌的假定粘附素和碳水化合物配体。

共生细菌必须在宿主粘膜表面定居，以发挥促进健康的特性，并通过其细胞表面粘附素与胃肠道（GIT）粘蛋白结合。为了发现病原粘附素及其配体以开发抗感染策略，已经进行了相当大的努力。然而，人们对凝集素样粘附素和相关的碳水化合物配体的了解却鲜为人知。在这项研究中，计算机方法被用于检测人共生副干酪乳杆菌亚种中表面暴露的粘附素。paracasei，一种有前途的益生菌，常用于乳制品发酵中，具有抗微生物活性。在13种粘附素候选物中，在该菌株中鉴定出3个依赖于分选酶的菌毛簇，并在体外证实了粘附素候选基因的表达。质谱分析证实存在表面粘附素延伸因子Tu和伴侣蛋白GroEL，但不存在菌毛表达。随后将全细胞在微阵列上孵育，该微阵列具有一组来自九种不同哺乳动物物种的GIT粘蛋白，两种人源细胞系和一个碳水化合物结构文库。将结合谱与两个已知的产生菌毛的乳杆菌，约翰逊乳杆菌和鼠李糖乳杆菌的结合谱进行比较，并且所有乳酸杆菌物种均显示出重叠但不同的特征，这可能表明区域特异性GIT定植的能力不同。此外，副干酪乳杆菌全细胞更倾向于与α-（2→3）连接的唾液酸和α-（1→2）连接的含岩藻糖的碳水化合物结构结合，包括血型A，B和O和Lewis抗原x， y和b。