title: Morphogenesis of the Bacillus anthracis spore.
abstract: Bacillus spp. and Clostridium spp. form a specialized cell type, called a spore, during a multistep differentiation process that is initiated in response to starvation. Spores are protected by a morphologically complex protein coat. The Bacillus anthracis coat is of particular interest because the spore is the infective particle of anthrax. We determined the roles of several B. anthracis orthologues of Bacillus subtilis coat protein genes in spore assembly and virulence. One of these, cotE, has a striking function in B. anthracis: it guides the assembly of the exosporium, an outer structure encasing B. anthracis but not B. subtilis spores. However, CotE has only a modest role in coat protein assembly, in contrast to the B. subtilis orthologue. cotE mutant spores are fully virulent in animal models, indicating that the exosporium is dispensable for infection, at least in the context of a cotE mutation. This has implications for both the pathophysiology of the disease and next-generation therapeutics. CotH, which directs the assembly of an important subset of coat proteins in B. subtilis, also directs coat protein deposition in B. anthracis. Additionally, however, in B. anthracis, CotH effects germination; in its absence, more spores germinate than in the wild type. We also found that SpoIVA has a critical role in directing the assembly of the coat and exosporium to an area around the forespore. This function is very similar to that of the B. subtilis orthologue, which directs the assembly of the coat to the forespore. These results show that while B. anthracis and B. subtilis rely on a core of conserved morphogenetic proteins to guide coat formation, these proteins may also be important for species-specific differences in coat morphology. We further hypothesize that variations in conserved morphogenetic coat proteins may play roles in taxonomic variation among species.
authors.affiliation: Department of Microbiology and Immunology, Loyola University Medical Center, 2160 South First Avenue, Bldg. 105, Rm. 3820, Maywood, IL 60153, USA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Giorno
authors.forename: Joel
authors.initials: J
authors.lastname: Bozue
authors.forename: Christopher
authors.initials: C
authors.lastname: Cote
authors.forename: Theresa
authors.initials: T
authors.lastname: Wenzel
authors.forename: Krishna-Sulayman
authors.initials: KS
authors.lastname: Moody
authors.forename: Michael
authors.initials: M
authors.lastname: Mallozzi
authors.forename: Matthew
authors.initials: M
authors.lastname: Ryan
authors.forename: Rong
authors.initials: R
authors.lastname: Wang
authors.forename: Ryszard
authors.initials: R
authors.lastname: Zielke
authors.forename: Janine R
authors.initials: JR
authors.lastname: Maddock
authors.forename: Arthur
authors.initials: A
authors.lastname: Friedlander
authors.forename: Susan
authors.initials: S
authors.lastname: Welkos
authors.forename: Adam
authors.initials: A
authors.lastname: Driks
mesh_terms: D001408:Bacillus anthracis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008858:Microscopy, Phase-Contrast; D008954:Models, Biological; D009154:Mutation; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013171:Spores, Bacterial / Q000235:genetics / Q000254:growth & development* / Q000648:ultrastructure
chemical_list: D001426:Bacterial Proteins