Moscoso Joana A, Korres Haralambos, George Divya T, Verma Naresh K
Division of Biomedical Science and Biochemistry, Research School of Biology, College of Medicine, Biology & Environment, Australian National University, Canberra, Australia.
Mol Membr Biol. 2010 Apr;27(2-3):104-13. doi: 10.3109/09687680903581267.
The serotype-specific glucosyltransferase, GtrV, is responsible for glucosylation of the O-antigen repeating unit of Shigella flexneri serotype 5a strains. GtrV is an integral inner membrane protein with two essential periplasmic loops: the large Loop 2 and the C-terminal Loop 10. In this study, the full length of the Loop 2 was shown to be necessary for GtrV function. Site-directed mutagenesis within this loop revealed that conserved aromatic and charged amino acids have a critical role in the formation of the active site. Sequential deletions of the C-terminal end indicated that this region may be essential for assembly of the protein in the cytoplasmic membrane. The highly conserved FWAED motif is thought to form the substrate-binding site and was found to be critical in GtrV and GtrX, a serotype-specific glucosyltransferase with homology to GtrV. The data presented constitutes a targeted analysis of the formation of the GtrV active site and highlights the essential role of the large periplasmic Loop 2 in its function.
血清型特异性葡糖基转移酶GtrV负责福氏志贺氏菌5a血清型菌株O抗原重复单元的糖基化。GtrV是一种整合内膜蛋白，有两个重要的周质环：大环2和C端环10。在本研究中，大环2的全长被证明对GtrV功能是必需的。该环内的定点诱变表明，保守的芳香族和带电荷氨基酸在活性位点形成中起关键作用。C端末端的连续缺失表明该区域可能对蛋白质在细胞质膜中的组装至关重要。高度保守的FWAED基序被认为形成底物结合位点，并且发现在GtrV和GtrX（一种与GtrV具有同源性的血清型特异性葡糖基转移酶）中至关重要。所呈现的数据构成了对GtrV活性位点形成的靶向分析，并突出了大的周质环2在其功能中的重要作用。
