title: Diversity of the Germination Apparatus inClostridium botulinumGroups I, II, III, and IV.
abstract: Clostridium botulinumis 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 inC. botulinumbased on comparative genomics analyses, withC. botulinumGroups I and III sharing similar pathways, which differ from those proposed forC. botulinumGroups 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 ofgerA, gerB, andgerCgenes (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. botulinumGroup I contained the largest variety ofgerXsubtypes, with threegerX1, threegerX2, and onegerX3subtypes, whileC. botulinumGroup III contained twogerX1types and onegerX4.C. botulinumGroups II and IV contained a single germinant receptor,gerX3andgerX1, respectively. It is likely that all fourC. botulinumGroups include a SpoVA channel involved in dipicolinic acid release. The cortex-lytic enzymes present inC. botulinumGroups I and III appear to be CwlJ and SleB, while inC. botulinumGroups II and IV, SleC appears to be important.
authors.affiliation: Gut Health and Food Safety, Institute of Food Research Norwich, UK.
authors.forename: Jason
authors.initials: J
authors.lastname: Brunt
authors.affiliation: Gut Health and Food Safety, Institute of Food ResearchNorwich, UK; School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of SurreyGuildford, UK.
authors.forename: Arnoud H M
authors.initials: AH
authors.lastname: van Vliet
authors.affiliation: Gut Health and Food Safety, Institute of Food Research Norwich, UK.
authors.forename: Fédor
authors.initials: F
authors.lastname: van den Bos
authors.affiliation: Gut Health and Food Safety, Institute of Food Research Norwich, UK.
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Carter
authors.affiliation: Gut Health and Food Safety, Institute of Food Research Norwich, UK.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Peck
keywords: C. botulinum; C. sporogenes; cortex-lytic enzymes; germinant receptors; germination; spore