The autolytic activity of cariogenic bacteria is useful as a target to develop antibacterial drugs.

致龋细菌的自溶活性可用作开发抗菌药物的靶标。

• 批准号: 17592183
• 负责人: SHIBATA Yukie
• 金额: $ 2.11万
• 依托单位: KYUSHU UNIVERCITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2005
• 资助国家: 日本
• 起止时间: 2005 至 2006
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-17592183/
• 关键词: caries; Streptococcus mutans; autolysin; autolytic activity; biofilm formation; catalytic domain; う蝕; う蝕細菌; バイオフィルム

The AtlA protein predicted for atlA of Streptococcus mutans Xc is composed of 979 amino acids with a molecular weight of 107,279 and has the conserved b-1,4-N-acetylmuramidase (lysozyme) domain in the C-terminal portion. Sodium dodecyl sulfate extracts of strain Xc showed two major bacteriolytic bands with molecular masses of 107 and 79 kDa, both of which were absent in an atlA-inactivated mutant. Western blot analysis revealed that the 79-kDa band is derived from the 107-kDa peptide by cleavage of its N-terminal portion. The inactivation of atlA resulted in a marked decrease of autolysis and the formation of very long chains of cells as compared with the parent strain. Although both the parent and mutant strains formed biofilms in the presence of sucrose, the biofilms formed by the mutant had a sponge-like architecture with large gaps and contained 30% less biomass than those of the parent strain. Furthermore, strain Xc formed the glucose-dependent, loose biofilms in the absence of sucrose, but the mutant lost this ability. These results suggest that AtlA may play an important role in biofilm formation by S. mutans. Next, we tried to purify the AtlA protein, but unfortunately failed it. The antibody produced against the C-terminal peptide containing the b-1,4-N-acetylmuramidase domain drastically inhibited the autolytic activity and the biofilm formation of strain Xc. This inhibition was specific to S. mutans among oral streptococci. These results indicate that the catalytic domain of AtlA is located at the C-terminus, suggesting that further characterization of this domain may provide a means to control cariogenic dental plaque formation.

预测的变形链球菌XC株ATLA蛋白由979个氨基酸组成，分子量为107,279，在C-末端含有保守的b-1，4-N-乙酰菌酰胺酶(溶菌酶)结构域。菌株XC的十二烷基硫酸钠提取物有两条主要的溶菌带，分子量分别为107和79 kDa，这两条带在ATLA失活突变株中都不存在。Western印迹分析表明，79 kDa条带是由107 kDa多肽N端裂解而来的。与亲本菌株相比，ATLA的失活导致自溶作用显著减少，并形成了很长的细胞链。虽然亲本菌株和突变菌株都在蔗糖存在下形成了生物膜，但突变菌株形成的生物膜具有海绵状的结构和较大的间隙，生物量比亲本菌株少30%。此外，菌株XC在没有蔗糖的情况下形成了依赖葡萄糖的疏松生物膜，但突变株失去了这种能力。这些结果表明，ATLA可能在变形链球菌生物膜的形成过程中起重要作用。接下来，我们试图提纯ATLA蛋白，但不幸的是失败了。针对含有b-1，4-N-乙酰壁酰胺酶结构域的C端肽产生的抗体显著抑制了XC菌株的自溶活性和生物被膜的形成。这种抑制作用是口腔链球菌中的变形链球菌所特有的。这些结果表明，ATLA的催化结构域位于C-末端，提示对该结构域的进一步鉴定可能为控制致龋性牙菌斑的形成提供一种手段。