State Key Laboratory of Microbial Technology, National Glycoengineering Research Center, Shandong University, Jinan 250100, PR China.
National Glycoengineering Research Center, Shandong University, Jinan 250100, PR China.
Microbiology (Reading). 2013 Mar;159(Pt 3):633-640. doi: 10.1099/mic.0.063784-0. Epub 2013 Jan 17.
Toxin-antitoxin (TA) systems in Escherichia coli may play a role in biofilm formation, but the mechanism involved remains debatable. It is not known whether the TA systems are responsible for extracellular DNA (eDNA) in biofilms. In this study, we investigated the function of the hipBA TA system in biofilm formation by Escherichia coli strain BW25113. First, the deletion of the HipBA TA system in E. coli BW25113 significantly reduced the biofilm biomass without antibiotic stress. Second, treatment of the BW25113 biofilm with DNase I caused a major reduction in biofilm formation, whereas similar treatment of the hipA mutant biofilm had only a minor effect. Third, the inactivation of HipA reduced the level of eDNA present in biofilm formation, and addition of BW25113 genomic DNA stimulated biofilm formation for both the wild-type and hipA mutant. Fourth, the wild-type cells underwent significantly more cell lysis than the hipA mutant. These results suggest that hipA plays a significant role during biofilm development and that eDNA is an important structural component of E. coli BW25113 biofilms. Thus, the TA system may enhance biofilm formation through DNA release.
大肠杆菌中的毒素-抗毒素（TA）系统可能在生物膜形成中发挥作用，但涉及的机制仍存在争议。目前尚不清楚 TA 系统是否负责生物膜中的胞外 DNA（eDNA）。在这项研究中，我们研究了大肠杆菌 BW25113 中 hipBA TA 系统在生物膜形成中的功能。首先，在没有抗生素胁迫的情况下，大肠杆菌 BW25113 中 HipBA TA 系统的缺失显著降低了生物膜生物量。其次，用 DNA 酶 I 处理 BW25113 生物膜会导致生物膜形成的大幅度减少，而类似地处理 hipA 突变体生物膜的效果则较小。第三，HipA 的失活降低了生物膜形成中存在的 eDNA 水平，并且 BW25113 基因组 DNA 的添加刺激了野生型和 hipA 突变体的生物膜形成。第四，与 hipA 突变体相比，野生型细胞经历了明显更多的细胞裂解。这些结果表明，hipA 在生物膜发育过程中起着重要作用，并且 eDNA 是大肠杆菌 BW25113 生物膜的重要结构组成部分。因此，TA 系统可能通过 DNA 释放来增强生物膜形成。
