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Molecular Analysis of Multiple Forms of the Streptococcus mutans Dextranase

多种变形链球菌葡聚糖酶的分子分析

基本信息

批准号：
09671867
负责人：
GOTO Nobuichi
金额：
$ 2.11万
依托单位：
Showa University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09671867/
关键词：
Dextranase Multiple form Streptococcus mutans Cariogenic bacteria Mutans streptococci 齲蝕原性細菌 Streptococcus mutans 齲蝕細菌 Mutans streptococci う蝕細菌

项目摘要

Molecular analysis of multiple forms of the Streptococcus mutans dextranase was studied by the approach of molecular genetics. In order to find out common characteristics of dextrnase (Dex) of cariogenic bacteria, complete nucleotide sequence of the S. downei dextranase gene was determined and compared with those of S. mutans and S. sobrinus. Homology analysis showed that the Dex was constituted by a conserved region and two variable regions. In addition, Dex of three species was detected as active multiple forms in Dex active staining. We, therefore, speculated that the conserved region was essential for Dex activity and the variable regions of N- and C-terminals were responsible for the multiple forms of the Dex.. On the basis of this speculation, we constructed mutants at two variable regions on the S. mutans Dex by genetic manipulation and examined influence to the multiple forms and activity of the Dex. Mutants within a C-terminal variable region showed the multiple forms with the Dex activity. Mutants defective both the C-terminal variable region and a part of the conserved regions disappeared not only the multiple forms but also the activity. On the other hand, mutants within a N-terminal variable region of the C-terminal mutant with Dex activity did not show both the multiple forms and the activity. These results indicated that the multiple forms of the Dex was responsible for degradation of the variable region of C-terminus and suggested that the conserved region would contain the catalytic sites such as active and substrate binding sites.

应用分子遗传学方法对变形链球菌葡聚糖酶的多种酶型进行了分子分析。为了解致龋菌右旋糖酐酶（Dex）的共同特性，对产龋菌S。downei葡聚糖酶基因的测定，并与S.和S. sobrinus。同源性分析表明，Dex基因由一个保守区和两个可变区组成。此外，Dex活性染色检测到三种Dex均为活性的多种形式。因此，我们推测，保守区是必不可少的Dex活性和N-和C-末端的可变区负责多种形式的Dex。在此基础上，我们在S.通过基因操作对变形杆菌Dex进行修饰，并检测其对Dex多种形式和活性的影响。C-末端可变区内的突变体显示具有Dex活性的多种形式。C端可变区和部分保守区缺失的突变体不仅丧失了多种形式，而且丧失了活性。另一方面，具有Dex活性的C-末端突变体的N-末端可变区内的突变体没有显示出多种形式和活性。这些结果表明，多种形式的Dex负责降解的C-末端的可变区，并建议保守的区域将包含催化位点，如活性和底物结合位点。