Fischetti V A, Jones K F, Hollingshead S K, Scott J R
Rockefeller University, New York, New York 10021.
Rev Infect Dis. 1988 Jul-Aug;10 Suppl 2:S356-9. doi: 10.1093/cid/10.supplement_2.s356.
Streptococcal M protein is a coiled-coil fibrillar structure extending about 60 nm from the cell wall. From DNA sequencing of the M6 protein gene, it has been determined that the C-terminal end contains a membrane anchor and an adjacent cell wall stabilization domain, both of which are similar to C-terminal regions of surface proteins in other gram-positive organisms. Studies with monoclonal antibodies revealed that the C-terminal half of the protein is conserved among M proteins of different serotypes, whereas the N-terminal half varies. The M protein contains tandem repeats, which, through homologous recombination, are responsible for the observed size variation of the M proteins from different streptococcal strains. M protein size mutants occur in a laboratory-grown culture at a frequency of 1/2,000 colony-forming units. DNA sequence analysis of the M gene in size mutants derived from a single strain suggests that sequence changes which result from homologous recombination may play a role in the antigenic variation of M protein.
链球菌M蛋白是一种从细胞壁延伸约60纳米的卷曲螺旋纤维状结构。通过对M6蛋白基因的DNA测序，已确定其C末端包含一个膜锚定结构和一个相邻的细胞壁稳定结构域，这两个结构域均与其他革兰氏阳性菌表面蛋白的C末端区域相似。单克隆抗体研究表明，该蛋白的C末端一半在不同血清型的M蛋白中是保守的，而N末端一半则有所不同。M蛋白包含串联重复序列，通过同源重组，这些重复序列导致了不同链球菌菌株中M蛋白观察到的大小变化。M蛋白大小突变体在实验室培养物中出现的频率为1/2000集落形成单位。对源自单一菌株的大小突变体中M基因的DNA序列分析表明，同源重组导致的序列变化可能在M蛋白的抗原变异中起作用。
