title: Functional characterisation of germinant receptors in Clostridium botulinum and Clostridium sporogenes presents novel insights into spore germination systems.
abstract: Clostridium botulinum is a dangerous pathogen that forms the highly potent botulinum toxin, which when ingested causes a deadly neuroparalytic disease. The closely related Clostridium sporogenes is occasionally pathogenic, frequently associated with food spoilage and regarded as the non-toxigenic equivalent of Group I C. botulinum. Both species form highly resistant spores that are ubiquitous in the environment and which, under favourable growth conditions germinate to produce vegetative cells. To improve the control of botulinum neurotoxin-forming clostridia, it is imperative to comprehend the mechanisms by which spores germinate. Germination is initiated following the recognition of small molecules (germinants) by a specific germinant receptor (GR) located in the spore inner membrane. The present study precisely defines clostridial GRs, germinants and co-germinants. Group I C. botulinum ATCC3502 contains two tricistronic and one pentacistronic GR operons, while C. sporogenes ATCC15579 has three tricistronic and one tetracistronic GR operons. Insertional knockout mutants, allied with characterisation of recombinant GRs shows for the first time that amino acid stimulated germination in C. botulinum requires two tri-cistronic encoded GRs which act in synergy and cannot function individually. Spore germination in C. sporogenes requires one tri-cistronic GR. Two other GRs form part of a complex involved in controlling the rate of amino-acid stimulated germination. The suitability of using C. sporogenes as a substitute for C. botulinum in germination studies and food challenge tests is discussed.
authors.affiliation: Gut Health and Food Safety, Institute of Food Research (IFR), Norwich Research Park, Colney, Norwich, Norfolk, United Kingdom.
authors.forename: Jason
authors.initials: J
authors.lastname: Brunt
authors.affiliation: Gut Health and Food Safety, Institute of Food Research (IFR), Norwich Research Park, Colney, Norwich, Norfolk, United Kingdom.
authors.forename: June
authors.initials: J
authors.lastname: Plowman
authors.affiliation: Gut Health and Food Safety, Institute of Food Research (IFR), Norwich Research Park, Colney, Norwich, Norfolk, United Kingdom.
authors.forename: Duncan J H
authors.initials: DJ
authors.lastname: Gaskin
authors.affiliation: Gut Health and Food Safety, Institute of Food Research (IFR), Norwich Research Park, Colney, Norwich, Norfolk, United Kingdom.
authors.forename: Manoa
authors.initials: M
authors.lastname: Itchner
authors.affiliation: Gut Health and Food Safety, Institute of Food Research (IFR), Norwich Research Park, Colney, Norwich, Norfolk, United Kingdom.
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Carter
authors.affiliation: Gut Health and Food Safety, Institute of Food Research (IFR), Norwich Research Park, Colney, Norwich, Norfolk, United Kingdom.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Peck
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015139:Blotting, Southern; D003013:Clostridium / Q000145:classification / Q000502:physiology*; D003015:Clostridium Infections / Q000235:genetics / Q000378:metabolism / Q000382:microbiology*; D005816:Genetic Complementation Test; D009154:Mutation / Q000235:genetics; D013171:Spores, Bacterial / Q000254:growth & development* / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins