Unique Regulatory Mechanism of Sporulation and Enterotoxin Production in Clostridium perfringens
Unique Regulatory Mechanism of Sporulation and Enterotoxin Production in Clostridium perfringens
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DOI：
10.1128/jb.02152-12
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发表时间：
2013-06-01
影响因子：
3.2
通讯作者：
Shimizu, Tohru
中科院分区：
文献类型：
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作者：
Ohtani, Kaori;Hirakawa, Hideki;Shimizu, Tohru
产气荚膜梭状芽胞杆菌引起人类气性坏疽和胃肠道疾病。与产气荚膜梭菌相关的食物中毒最常见的原因是消耗产气荚膜梭菌营养细胞，然后在肠道中产生孢子和肠毒素。尽管孢子形成在产气荚膜芽孢杆菌的发病机制中很重要，但孢子形成调控的细节尚未得到充分的定义。在这项研究中，微阵列和生物信息学分析鉴定了一个候选基因（RNA调节因子virX），用于抑制产气荚膜荚膜菌孢子形成的正调节因子（Spo0A和sigma因子）的编码基因。在食物中毒菌株SM101中构建的virX突变体的产孢效率远高于野生型。在virX突变体培养2.5 h时，sigE、sigF和sigK的转录被强烈诱导。此外，在virX突变体中，肠毒素基因的转录也被强烈诱导。Western blotting证实，virX突变体的肠毒素产生水平高于野生型。这些观察结果表明，virX突变体中较高水平的产孢和肠毒素产生是由于virX基因失活所致。由于没有在任何芽孢杆菌中发现virX同源物，但在其他梭状芽孢杆菌中存在，因此我们的研究结果进一步确定了芽孢杆菌和某些梭状芽孢杆菌之间对孢子形成的调节存在差异。virX RNA调节因子在厌氧肉食者产气荚膜梭菌的生活方式从植物状态（气性坏疽）到孢子状态（食物中毒）的急剧转变中起着关键作用。
Clostridium perfringens causes gas gangrene and gastrointestinal (GI) diseases in humans. The most common cause of C. perfringens-associated food poisoning is the consumption of C. perfringens vegetative cells followed by sporulation and production of enterotoxin in the gut. Despite the importance of spore formation in C. perfringens pathogenesis, the details of the regulation of sporulation have not yet been defined fully. In this study, microarray and bioinformatic analyses identified a candidate gene (the RNA regulator virX) for the repression of genes encoding positive regulators (Spo0A and sigma factors) of C. perfringens sporulation. A virX mutant constructed in the food poisoning strain SM101 had a much higher sporulation efficiency than that of the wild type. The transcription of sigE, sigF, and sigK was strongly induced at 2.5 h of culture of the virX mutant. Moreover, the transcription of the enterotoxin gene was also strongly induced in the virX mutant. Western blotting confirmed that the levels of enterotoxin production were higher in the virX mutant than in the wild type. These observations indicated that the higher levels of sporulation and enterotoxin production in the virX mutant were specifically due to inactivation of the virX gene. Since virX homologues were not found in any Bacillus species but were present in other clostridial species, our findings identify further differences in the regulation of sporulation between Bacillus and certain Clostridium species. The virX RNA regulator plays a key role in the drastic shift in lifestyle of the anaerobic flesh eater C. perfringens between the vegetative state (for gas gangrene) and the sporulating state (for food poisoning).