Dpr蛋白在寡发酵链球菌抗过氧化氢中的作用

摘要：【目的】寡发酵链球菌（Streptococcus oligofermentans）是从无龋人的口腔中分离到的一株链球菌，好氧条件下产生、同时也耐受高浓度（4.4 mmol/L）的过氧化氢。本研究探讨dpr基因对寡发酵链球菌抗过氧化氢的贡献。【方法】克隆和表达寡发酵链球菌dpr基因，分析Dpr蛋白的功能；构建寡发酵链球菌的dpr基因突变株，比较野生株和突变株对不同浓度过氧化氢的耐受程度；并将寡发酵链球菌dpr基因克隆到对过氧化氢耐受力低的变形链球菌中，分析其对变形链球菌过氧化氢耐受能力的影响。【结果】

Role of Dpr in hydrogen peroxide tolerance of Streptococcus oligofermentans

Objective]Streptococcus oligqfermentans was a newly characterized streptococcal species,which we isolated from dental plaques of carious-free humans. Our previous work indicated that in aerobic environments,it produced, as well as survived high concentration of hydrogen peroxide (4.4 mmol/L) . This study analyzed the function of dpr gene in hydrogen peroxide tolerance of Streptococcus oligofermentans . Methods ] Cloned and expressed the dpr gene, and characterized Dpr protein. We constructed the dpr mutant strain of S. oligfermentans and detected its susceptivity to hydrogen peroxide. Furthermore, S. oligqfermentans dpr gene was cloned into S . mutans, and its susceptivity to hydrogen peroxide was tested. Results] S. oligofermentans dpr mutant strain was much more susceptive to hydrogen peroxide than the wild type, and introduction of its dpr gene into S . mutans could enhance the later's hydrogen peroxide tolerant ability. Dpr proteins could bind irons , but not to DNA. Conclusion] dpr gene of S . oligofermentans has significant role in hydrogen peroxide tolerance of the host strain, while Dpr protein may have other oxidant-damage protective mechanisms except for iron-binding. Keywords: Streptococcus oligqfermentans,Dps like peroxide resistance gene, hydrogen peroxide toleranc.