Wang Lei, Wang Quan, Reeves Peter R
TEDA School of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin, 300457, China.
Subcell Biochem. 2010;53:123-52. doi: 10.1007/978-90-481-9078-2_6.
The O antigen, consisting of many repeats of an oligosaccharide unit, is part of the lipopolysaccharide (LPS) in the outer membrane of Gram-negative bacteria. It is on the cell surface and appears to be a major target for both immune system and bacteriophages, and therefore becomes one of the most variable cell constituents. The variability of the O antigen provides the major basis for serotyping schemes of Gram-negative bacteria. The genes responsible for the synthesis of O antigen are usually in a single cluster known as O antigen gene cluster, and their location on the chromosome within a species is generally conserved. Three O antigen biosynthesis pathways including Wzx/Wzy, ABC-transporter and Synthase have been discovered. In this chapter, the traditional and molecular O serotyping schemes are compared, O antigen structures and gene clusters of well-studied species are described, processes for formation and distribution of the variety of O antigens are discussed, and finally, the role of O antigen in bacterial virulence.
O抗原由寡糖单元的多个重复序列组成，是革兰氏阴性菌外膜中脂多糖（LPS）的一部分。它位于细胞表面，似乎是免疫系统和噬菌体的主要靶点，因此成为最易变的细胞成分之一。O抗原的变异性为革兰氏阴性菌的血清分型方案提供了主要依据。负责O抗原合成的基因通常位于一个称为O抗原基因簇的单一簇中，它们在一个物种染色体上的位置通常是保守的。已发现三种O抗原生物合成途径，包括Wzx/Wzy、ABC转运体和合成酶途径。在本章中，对传统的和分子O血清分型方案进行了比较，描述了经过充分研究的物种的O抗原结构和基因簇，讨论了各种O抗原的形成和分布过程，最后，阐述了O抗原在细菌毒力中的作用。
