Diversity of the Germination Apparatus in Clostridium botulinum Groups I, II, III, and IV.
Diversity of the Germination Apparatus in Clostridium botulinum Groups I, II, III, and IV.
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DOI：
10.3389/fmicb.2016.01702
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发表时间：
2016
影响因子：
5.2
通讯作者：
Peck MW
中科院分区：
文献类型：
--
作者：
Brunt J;van Vliet AH;van den Bos F;Carter AT;Peck MW
肉毒梭菌是一种高度危险的病原体，它会形成非常抗药性的内孢子，这种内孢子在环境中随处可见，在有利的条件下，它会萌发产生营养细胞，然后繁殖并形成特别强大的肉毒杆菌神经毒素。为了更好地控制肉毒神经毒素形成梭状芽胞杆菌，了解孢子萌发的机制是重要的。在这里，我们提出了基于比较基因组学分析的肉毒杆菌孢子萌发模型，肉毒杆菌I组和III组的孢子萌发途径相似，不同于对肉毒杆菌II组和IV组的建议。所有的孢子都在与萌发受体相互作用的氨基酸的响应下萌发，识别出四种类型的萌发受体[由gerA、gerb和gerc基因(GerX)的不同组合编码]。有3个基因簇具有类似ABC的构型：ABC[gerX1]、ABABCB[gerX2]和ACxBBB[gerX4]，以及单个CA-B[gerX3]基因簇。大多数萌发受体类型的亚型已经被确定，每个簇的单个GerX亚基在系统发育树中显示出类似的分组。肉毒杆菌I组包含的gerX亚型种类最多，有3个gerX1、3个gerX2和1个gerX3亚型，而肉毒杆菌III组包含2个gerX1类型和1个gerX4。肉毒杆菌第II组和第IV组分别含有一个萌发受体gerX3和gerX1。很可能所有四个肉毒杆菌群都包括一个参与二吡啶甲酸释放的SpoVA通道。肉毒杆菌I组和III组中存在的皮质裂解酶似乎是CwlJ和Slib，而在C组肉毒杆菌II和IV中，SLEC似乎是重要的。
Clostridium botulinum is a highly dangerous pathogen that forms very resistant endospores that are ubiquitous in the environment, and which, under favorable conditions germinate to produce vegetative cells that multiply and form the exceptionally potent botulinum neurotoxin. To improve the control of botulinum neurotoxin-forming clostridia, it is important to understand the mechanisms involved in spore germination. Here we present models for spore germination in C. botulinum based on comparative genomics analyses, with C. botulinum Groups I and III sharing similar pathways, which differ from those proposed for C. botulinum Groups II and IV. All spores germinate in response to amino acids interacting with a germinant receptor, with four types of germinant receptor identified [encoded by various combinations of gerA, gerB, and gerC genes (gerX)]. There are three gene clusters with an ABC-like configuration; ABC [gerX1], ABABCB [gerX2] and ACxBBB [gerX4], and a single CA-B [gerX3] gene cluster. Subtypes have been identified for most germinant receptor types, and the individual GerX subunits of each cluster show similar grouping in phylogenetic trees. C. botulinum Group I contained the largest variety of gerX subtypes, with three gerX1, three gerX2, and one gerX3 subtypes, while C. botulinum Group III contained two gerX1 types and one gerX4. C. botulinum Groups II and IV contained a single germinant receptor, gerX3 and gerX1, respectively. It is likely that all four C. botulinum Groups include a SpoVA channel involved in dipicolinic acid release. The cortex-lytic enzymes present in C. botulinum Groups I and III appear to be CwlJ and SleB, while in C. botulinum Groups II and IV, SleC appears to be important.