Regulation of Streptococcus gordonii glucosyltransferase.
Regulation of Streptococcus gordonii glucosyltransferase.
复制标题
戈登链球菌葡萄糖基转移酶的调节。
DOI：
10.1007/978-1-4899-1825-3_154
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发表时间：
1997
影响因子：
--
通讯作者：
Clewell,DB
中科院分区：
文献类型：
--
作者：
Vickerman,MM;Clewell,DB
早期牙菌斑微生物戈登链球菌（Streptococcus gordonii）具有单一的葡糖基转移酶（GTF），可从蔗糖中生成α 1，3-和α 1，6-连接的葡聚糖（5）。亲本菌株查利斯CH 1产生的葡聚糖赋予在蔗糖琼脂上生长的菌落坚硬、有粘性、蔗糖促进的表型（Spp+）（3）。Spp−变异体在蔗糖琼脂上较软，GTF活性水平降低，从菌株CH 1中自发产生，频率为10− 5至10−3。许多Spp−菌株以相似的频率恢复为Spp+（7）。菌株CH 1 GTF结构基因gtfG编码一种推测分子量为173，875的加工蛋白（6）。gtfG在核苷酸和推测氨基酸水平上与其他口腔链球菌gtf基因相似，编码一个推定的蔗糖水解活性位点和一系列与葡聚糖结合有关的6个羧基末端直接重复序列（图1）。紧接gtfGisrgg的上游，是唯一描述的agtf基因的调控决定子。rggen编码一种推定的胞质蛋白，其可以反式作用以增加egtfG转录（2）。为了获得更多的见解监管的S。gordoniiiGTF活性在DNA水平上，已知参与GTF表达的区域的核苷酸序列在几个自发的Spp−菌株中进行了检查。
The early dental plaque organismStreptococcus gordoniihas a single glucosyltransferase (GTF) enzyme that makes both α1,3- and α1,6-linked glucans from sucrose(5). The glucans made by the parental strain Challis CH1 confer a hard, cohesive,sucrose-promotedphenotype (Spp+) to colonies grown on sucrose agar(3). Spp−variants, which are soft on sucrose agar and have decreased levels of GTF activity, arise spontaneously from strain CH1 at frequencies of 10−5to 10−3. Many Spp−strains revert to Spp+at similar frequencies(7). The strain CH1 GTF structural gene,gtfG, encodes a processed protein with a deduced molecular weight of 173,875(6).gtfGis similar to other oral streptococcalgtfgenes at both the nucleotide and deduced amino acid levels encoding a putative active site for sucrose hydrolysis and a series of 6 carboxyl terminal direct repeats implicated in glucan binding (Fig. 1). Immediately upstream fromgtfGisrgg, the only described regulatory determinant for agtfgene.rggencodes a putative cytoplasmic protein which can act intransto increasegtfGtranscription(2). To gain additional insights into regulation ofS. gordoniiGTF activity at the DNA level, nucleotide sequences of regions known to be involved in GTF expression were examined in several spontaneous Spp−strains.