Yamashita Yoshihisa, Tsukioka Yuichi, Nakano Yoshio, Tomihisa Kiyotaka, Oho Takahiko, Koga Toshihiko
Department of Preventive Dentistry, Kyushu University Faculty of Dentistry, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Microbiology (Reading). 1998 May;144 ( Pt 5):1235-1245. doi: 10.1099/00221287-144-5-1235.
A gene encoding glucose-1-phosphate uridylyltransferase (EC 2.7.7.9) was isolated from Streptococcus mutans. A cell extract of Escherichia coli expressing the cloned gene exhibited glucose-1-phosphate uridylyltransferase activity. The enzyme catalyses the conversion of D-glucose 1-phosphate and UTP into UDP-D-glucose. Rabbit antiserum against the serotype-c-specific antigen did not react with autoclaved extracts from mutant cells in which the cloned gene was insertionally inactivated. The glucose content of the cell-wall preparation purified from the mutant was very much lowered, whereas there was no observable decrease in the content of rhamnose. When the mutant strain was grown in an acidic environment, its cell viability was much lower than that of the wild-type. These results suggest that UDP-D-glucose functions not only as an immediate precursor of the serotype-c-specific antigen of S. mutans (as a glucose donor for side-chain formation), but is also important for the organism's viability in environmental conditions of low pH.
从变形链球菌中分离出一个编码葡萄糖-1-磷酸尿苷酰转移酶（EC 2.7.7.9）的基因。表达该克隆基因的大肠杆菌细胞提取物表现出葡萄糖-1-磷酸尿苷酰转移酶活性。该酶催化D-葡萄糖1-磷酸和UTP转化为UDP-D-葡萄糖。针对血清型c特异性抗原的兔抗血清不与克隆基因被插入失活的突变细胞的高压灭菌提取物发生反应。从突变体中纯化的细胞壁制剂中的葡萄糖含量大大降低，而鼠李糖含量没有明显下降。当突变菌株在酸性环境中生长时，其细胞活力远低于野生型。这些结果表明，UDP-D-葡萄糖不仅作为变形链球菌血清型c特异性抗原的直接前体（作为侧链形成的葡萄糖供体）发挥作用，而且对于该生物体在低pH环境条件下的生存能力也很重要。
