title: Cooperativity and interference of germination pathways in Bacillus anthracis spores.
abstract: Spore germination is the first step to Bacillus anthracis pathogenicity. Previous work has shown that B. anthracis spores use germination (Ger) receptors to recognize amino acids and nucleosides as germinants. Genetic analysis has putatively paired each individual Ger receptor with a specific germinant. However, Ger receptors seem to be able to partially compensate for each other and recognize alternative germinants. Using kinetic analysis of B. anthracis spores germinated with inosine and L-alanine, we previously determined kinetic parameters for this germination process and showed binding synergy between the cogerminants. In this work, we expanded our kinetic analysis to determine kinetic parameters and binding order for every B. anthracis spore germinant pair. Our results show that germinant binding can exhibit positive, neutral, or negative cooperativity. Furthermore, different germinants can bind spores by either a random or an ordered mechanism. Finally, simultaneous triggering of multiple germination pathways shows that germinants can either cooperate or interfere with each other during the spore germination process. We postulate that the complexity of germination responses may allow B. anthracis spores to respond to different environments by activating different germination pathways.
authors.affiliation: Department of Chemistry, University of Nevada, Las Vegas, Las Vegas, Nevada 89154, USA.
authors.forename: Helen
authors.initials: H
authors.lastname: Luu
authors.forename: Monique
authors.initials: M
authors.lastname: Akoachere
authors.forename: Manomita
authors.initials: M
authors.lastname: Patra
authors.forename: Ernesto
authors.initials: E
authors.lastname: Abel-Santos
mesh_terms: D000596:Amino Acids / Q000378:metabolism / Q000494:pharmacology*; D001408:Bacillus anthracis / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects / Q000502:physiology*; D006358:Hot Temperature; D007288:Inosine / Q000494:pharmacology; D011485:Protein Binding; D015398:Signal Transduction; D013171:Spores, Bacterial / Q000502:physiology
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D007288:Inosine