Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands.
Groningen Biomolecular Sciences and Biotechnology Institute, Nijenborgh 7, 9747 AG Groningen, The Netherlands.
ACS Chem Biol. 2021 Jan 15;16(1):165-175. doi: 10.1021/acschembio.0c00848. Epub 2021 Jan 5.
Processivity is an important feature of enzyme families such as DNA polymerases, polysaccharide synthases, and protein kinases, to ensure high fidelity in biopolymer synthesis and modification. Here, we reveal processive character in the family of cytoplasmic protein -glycosyltransferases (NGTs). Through various activity assays, intact protein mass spectrometry, and proteomics analysis, we established that NGTs from nontypeable and modify an adhesin protein fragment in a semiprocessive manner. Molecular modeling studies suggest that the processivity arises from the shallow substrate binding groove in NGT, which promotes the sliding of the adhesin over the surface to allow further glycosylations without temporary dissociation. We hypothesize that the processive character of these bacterial protein glycosyltransferases is the mechanism to ensure multisite glycosylation of adhesins , thereby creating the densely glycosylated proteins necessary for bacterial self-aggregation and adherence to human cells, as a first step toward infection.
延伸性是聚合酶、多糖合成酶和蛋白激酶等酶家族的一个重要特征，可确保生物聚合物合成和修饰的高保真度。在这里，我们揭示了胞质蛋白糖基转移酶（NGTs）家族的延伸性特征。通过各种活性测定、完整蛋白质质谱和蛋白质组学分析，我们证实了非定型和 型的 NGT 以半延伸的方式修饰粘附蛋白片段。分子建模研究表明，延伸性源于 NGT 中浅的底物结合槽，该结合槽促进了粘附蛋白在表面上的滑动，从而允许在不暂时解离的情况下进一步进行糖基化。我们假设这些细菌蛋白糖基转移酶的延伸性特征是确保粘附素多部位糖基化的机制，从而产生细菌自身聚集和黏附到人细胞所必需的高度糖基化蛋白，作为感染的第一步。
