Gilmore K S, Russell R R, Ferretti J J
Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City 73190.
Infect Immun. 1993 Apr;61(4):1246-50. doi: 10.1128/iai.61.4.1246-1250.1993.
The gtfI and gtfS genes of Streptococcus downei were investigated to determine the contribution of the respective enzymes to glucan production in the presence and absence of other glucosyltransferases. Extracts of Escherichia coli expressing cloned gtfS produced a short linear dextran from sucrose which could act as a primer for insoluble glucan synthesis when mixed with extracts of a strain expressing recombinant gtfI. To elucidate the contribution of gtfS to glucan production by S. downei, a mutant was constructed by insertionally inactivating gtfS. S. downei (gtfS mutant) colonies exhibited a marked phenotypic change on sucrose-containing media and a decreased ability to adhere to glass and produced no detectable water-insoluble glucan. These experiments confirm that expression of gtfS is essential for normal insoluble glucan synthesis by S. downei.
研究了唐氏链球菌的gtfI和gtfS基因，以确定在存在和不存在其他葡糖基转移酶的情况下，各自的酶对葡聚糖产生的贡献。表达克隆的gtfS的大肠杆菌提取物从蔗糖产生一种短的线性葡聚糖，当与表达重组gtfI的菌株提取物混合时，它可以作为不溶性葡聚糖合成的引物。为了阐明gtfS对唐氏链球菌产生葡聚糖的贡献，通过插入失活gtfS构建了一个突变体。唐氏链球菌（gtfS突变体）菌落在含蔗糖的培养基上表现出明显的表型变化，并且粘附于玻璃的能力下降，并且没有产生可检测到的水不溶性葡聚糖。这些实验证实，gtfS的表达对于唐氏链球菌正常的不溶性葡聚糖合成是必不可少的。
