Hong K
Laboratories for Bioengineering and Research, ICR Pharmaceuticals Co., Ltd, Kobe, Japan.
Res Microbiol. 2000 Jan-Feb;151(1):29-36. doi: 10.1016/s0923-2508(00)00130-3.
The emm gene typing of GAS (group A streptococcus) strains Sv and Su and the molecular structure of the vir regulon were decided. An emm(-like) gene from the chromosomal DNA of GAS strain Sv was amplified with forward and reverse primers, which were selected from the best conserved portion in leader sequences of different strains and the C-terminal conserved portion, respectively, for determination of the M protein gene type. Strain Sv was defined as serotype M23, because deduced N-terminal amino acid positions of the products are identical to those of the M type 23 (emml) gene derived from GAS strain M23-MEMPHIS (M serotype 23, GenBank accession number U11953). When the vir regulon of strain Sv was examined by polymerase chain reaction mapping and compared with that of GAS strain Su, they had a similar size in length. In addition, when sequencing analysis of the DNA fragment of 4791 base pairs (bp) encoding three open reading frames (orf, mga, and emm) and the upstream region of scpA from genomic DNAs of both strains was performed, the sequence of the DNA from strain Sv was, except for 1 bp (T for C at position 4124), identical to that of the DNA from strain Su. These data show that both strains possess the genes in the order of mga (virR or mry) -emm -scpA designated as the small vir regulon. The effect of the formation of alternative pathway C3 convertase of complement on the GAS strains Sv and Su was also examined. When GAS strains Sv and Su were incubated in NHS containing radiolabeled C3 in the presence of Mg-EGTA, binding of C3 to Su bacteria was dose-dependent, whereas less binding of C3 to Sv bacteria was seen. Taken together, the data suggest that M protein could be expressed on the surface of the Sv bacteria, but not on the Su bacteria.
确定了A群链球菌（GAS）菌株Sv和Su的emm基因分型以及毒力调节子的分子结构。用分别从不同菌株前导序列中最保守部分和C末端保守部分选取的正向和反向引物，扩增GAS菌株Sv染色体DNA中的一个emm（类）基因，以确定M蛋白基因类型。菌株Sv被定义为血清型M23，因为推导的产物N末端氨基酸位置与源自GAS菌株M23-MEMPHIS（M血清型23，GenBank登录号U11953）的M23型（emml）基因相同。当通过聚合酶链反应图谱分析检测菌株Sv的毒力调节子并与GAS菌株Su的进行比较时，它们的长度大小相似。此外，对两株菌基因组DNA中编码三个开放阅读框（orf、mga和emm）的4791个碱基对（bp）的DNA片段以及scpA上游区域进行测序分析时，菌株Sv的DNA序列除了1个碱基（第4124位的T替换为C）外，与菌株Su的DNA序列相同。这些数据表明，两株菌都拥有按mga（virR或mry）-emm-scpA顺序排列的基因，该顺序被指定为小毒力调节子。还检测了补体替代途径C3转化酶的形成对GAS菌株Sv和Su的影响。当GAS菌株Sv和Su在含有放射性标记C3的NHS中于Mg-EGTA存在下孵育时，C3与Su细菌的结合呈剂量依赖性，而与Sv细菌的结合较少。综上所述，数据表明M蛋白可能在Sv细菌表面表达，但不在Su细菌表面表达。
