title: Thermoregulation of Biofilm Formation in Burkholderia pseudomallei Is Disrupted by Mutation of a Putative Diguanylate Cyclase.
abstract: Burkholderia pseudomallei, a tier 1 select agent and the etiological agent of melioidosis, transitions from soil and aquatic environments to infect a variety of vertebrate and invertebrate hosts. During the transition from an environmental saprophyte to a mammalian pathogen,B. pseudomalleiencounters and responds to rapidly changing environmental conditions. Environmental sensing systems that control cellular levels of cyclic di-GMP promote pathogen survival in diverse environments. Cyclic di-GMP controls biofilm production, virulence factors, and motility in many bacteria. This study is an evaluation of cyclic di-GMP-associated genes that are predicted to metabolize and interact with cyclic di-GMP as identified from the annotated genome ofB. pseudomallei1026b. Mutants containing transposon disruptions in each of these genes were characterized for biofilm formation and motility at two temperatures that reflect conditions that the bacteria encounter in the environment and during the infection of a mammalian host. Mutants with transposon insertions in a known phosphodiesterase (cdpA) and a predicted hydrolase (Bp1026b_I2285) gene exhibited decreased motility regardless of temperature. In contrast, the phenotypes exhibited by mutants with transposon insertion mutations in a predicted diguanylate cyclase gene (Bp1026b_II2523) were strikingly influenced by temperature and were dependent on a conserved GG(D/E)EF motif. The transposon insertion mutant exhibited enhanced biofilm formation at 37°C but impaired biofilm formation at 30°C. These studies illustrate the importance of studying behaviors regulated by cyclic di-GMP under varied environmental conditions in order to better understand cyclic di-GMP signaling in bacterial pathogens.IMPORTANCEThis report evaluates predicted cyclic di-GMP binding and metabolic proteins fromBurkholderia pseudomallei1026b, a tier 1 select agent and the etiologic agent of melioidosis. Transposon insertion mutants with disruptions in each of the genes encoding these predicted proteins were characterized in order to identify key components of theB. pseudomalleicyclic di-GMP-signaling network. A predicted hydrolase and a phosphodiesterase that modulate swimming motility were identified, in addition to a diguanylate cyclase that modulates biofilm formation and motility in response to temperature. These studies warrant further evaluation of the contribution of cyclic di-GMP to melioidosis in the context of pathogen acquisition from environmental reservoirs and subsequent colonization, dissemination, and persistence within the host.
authors.affiliation: Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: Brooke A
authors.initials: BA
authors.lastname: Plumley
authors.affiliation: Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: Kevin H
authors.initials: KH
authors.lastname: Martin
authors.affiliation: Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: Grace I
authors.initials: GI
authors.lastname: Borlee
authors.affiliation: Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: Nicole L
authors.initials: NL
authors.lastname: Marlenee
authors.affiliation: Department of Microbiology and Immunology, University of South Alabama, Mobile, Alabama, USA.
authors.forename: Mary N
authors.initials: MN
authors.lastname: Burtnick
authors.affiliation: Department of Microbiology and Immunology, University of South Alabama, Mobile, Alabama, USA.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Brett
authors.affiliation: Department of Molecular Microbiology and Immunology, University of Nevada-Reno, Reno, Nevada, USA.
authors.forename: David P
authors.initials: DP
authors.lastname: AuCoin
authors.affiliation: Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Bowen
authors.affiliation: Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida, USA.
authors.forename: Herbert P
authors.initials: HP
authors.lastname: Schweizer
authors.affiliation: Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, Colorado, USA Brad.Borlee@colostate.edu.
authors.forename: Bradley R
authors.initials: BR
authors.lastname: Borlee
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development*; D016957:Burkholderia pseudomallei / Q000502:physiology*; D019295:Computational Biology; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000378:metabolism; D004251:DNA Transposable Elements; D016208:Databases, Factual; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D019143:Evolution, Molecular; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D009154:Mutation; D019761:Phosphorus-Oxygen Lyases / Q000235:genetics / Q000378:metabolism*; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D029968:Escherichia coli Proteins; C062025:bis(3',5')-cyclic diguanylic acid; D019761:Phosphorus-Oxygen Lyases; C060720:diguanylate cyclase; D006152:Cyclic GMP
keywords: Burkholderia pseudomallei; biofilm; cyclic di-GMP; diguanylate cyclase; motility; phosphodiesterase; second messenger