title: Poly(3-hydroxybutyrate) fuels the tricarboxylic acid cycle and de novo lipid biosynthesis during Bacillus anthracis sporulation.
abstract: Numerous bacteria accumulate poly(3-hydroxybutyrate) (PHB) as an intracellular reservoir of carbon and energy in response to imbalanced nutritional conditions. In Bacillus spp., where PHB biosynthesis precedes the formation of the dormant cell type called the spore (sporulation), the direct link between PHB accumulation and efficiency of sporulation was observed in multiple studies. Although the idea of PHB as an intracellular carbon and energy source fueling sporulation was proposed several decades ago, the mechanisms underlying PHB contribution to sporulation have not been defined. Here, we demonstrate that PHB deficiency impairs Bacillus anthracis sporulation through diminishing the energy status of the cells and by reducing carbon flux into the tricarboxylic acid (TCA) cycle and de novo lipid biosynthesis. Consequently, this metabolic imbalance decreased biosynthesis of the critical components required for spore integrity and resistance, such as dipicolinic acid (DPA) and the spore's inner membrane. Supplementation of the PHB deficient mutant with exogenous fatty acids overcame these sporulation defects, highlighting the importance of the TCA cycle and lipid biosynthesis during sporulation. Combined, the results of this work reveal the molecular mechanisms of PHB contribution to B. anthracis sporulation and provide valuable insight into the metabolic requirements for this developmental process in Bacillus species.
authors.affiliation: Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, 68198, USA.
authors.forename: Marat R
authors.initials: MR
authors.lastname: Sadykov
authors.affiliation: Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, 68198, USA.
authors.forename: Jong-Sam
authors.initials: JS
authors.lastname: Ahn
authors.affiliation: Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, 68198, USA.
authors.forename: Todd J
authors.initials: TJ
authors.lastname: Widhelm
authors.affiliation: Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, 68198, USA.
authors.forename: Valerie M
authors.initials: VM
authors.lastname: Eckrich
authors.affiliation: Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, 68198, USA.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Endres
authors.affiliation: Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, Maywood, IL, 60153, USA.
authors.forename: Adam
authors.initials: A
authors.lastname: Driks
authors.affiliation: Emergent BioSolutions Lansing, MI, 48906, USA.
authors.forename: Gregory E
authors.initials: GE
authors.lastname: Rutkowski
authors.affiliation: Battelle Memorial Institute, Fort Detrick, MD, 21702, USA.
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Wingerd
authors.affiliation: Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, 68198, USA.
authors.forename: Kenneth W
authors.identifier: http://orcid.org/0000-0001-9521-3540
authors.initials: KW
authors.lastname: Bayles
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000378:metabolism; D001408:Bacillus anthracis / Q000254:growth & development / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism; D002952:Citric Acid Cycle; D006885:Hydroxybutyrates / Q000378:metabolism*; D008055:Lipids / Q000096:biosynthesis*; D010848:Picolinic Acids / Q000378:metabolism; D011091:Polyesters / Q000378:metabolism*; D013171:Spores, Bacterial / Q000378:metabolism; D000094122:Polyhydroxybutyrates
chemical_list: D020155:3-Hydroxybutyric Acid; D001426:Bacterial Proteins; D006885:Hydroxybutyrates; D008055:Lipids; D010848:Picolinic Acids; D011091:Polyesters; C003182:poly-beta-hydroxybutyrate; D000094122:Polyhydroxybutyrates; C004860:dipicolinic acid