title: Diguanylate cyclase null mutant reveals that C-Di-GMP pathway regulates the motility and adherence of the extremophile bacterium Acidithiobacillus caldus.
abstract: An understanding of biofilm formation is relevant to the design of biological strategies to improve the efficiency of the bioleaching process and to prevent environmental damages caused by acid mine/rock drainage. For this reason, our laboratory is focused on the characterization of the molecular mechanisms involved in biofilm formation in different biomining bacteria. In many bacteria, the intracellular levels of c-di-GMP molecules regulate the transition from the motile planktonic state to sessile community-based behaviors, such as biofilm development, through different kinds of effectors. Thus, we recently started a study of the c-di-GMP pathway in several biomining bacteria including Acidithiobacillus caldus. C-di-GMP molecules are synthesized by diguanylate cyclases (DGCs) and degraded by phosphodiesterases (PDEs). We previously reported the existence of intermediates involved in c-di-GMP pathway from different Acidithiobacillus species. Here, we report our work related to At. caldus ATCC 51756. We identified several putative-ORFs encoding DGC and PDE and effector proteins. By using total RNA extracted from At. caldus cells and RT-PCR, we demonstrated that these genes are expressed. We also demonstrated the presence of c-di-GMP by mass spectrometry and showed that genes for several of the DGC enzymes were functional by heterologous genetic complementation in Salmonella enterica serovar Typhimurium mutants. Moreover, we developed a DGC defective mutant strain (Δc1319) that strongly indicated that the c-di-GMP pathway regulates the swarming motility and adherence to sulfur surfaces by At. caldus. Together, our results revealed that At. caldus possesses a functional c-di-GMP pathway which could be significant for ores colonization during the bioleaching process.
authors.affiliation: Laboratorio de Comunicación Bacteriana, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
authors.forename: Matías
authors.initials: M
authors.lastname: Castro
authors.affiliation: Department of Microbiology, Stellenbosch University, Stellenbosch, South Africa.
authors.forename: Shelly M
authors.initials: SM
authors.lastname: Deane
authors.affiliation: Laboratorio de Comunicación Bacteriana, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
authors.forename: Lina
authors.initials: L
authors.lastname: Ruiz
authors.affiliation: Department of Microbiology, Stellenbosch University, Stellenbosch, South Africa.
authors.forename: Douglas E
authors.initials: DE
authors.lastname: Rawlings
authors.affiliation: Laboratorio de Comunicación Bacteriana, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Guiliani
mesh_terms: D042763:Acidithiobacillus / Q000502:physiology*; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005816:Genetic Complementation Test; D053858:Metabolic Networks and Pathways; D009154:Mutation; D019761:Phosphorus-Oxygen Lyases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D054730:Protein Interaction Domains and Motifs; D015398:Signal Transduction
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C062025:bis(3',5')-cyclic diguanylic acid; D019761:Phosphorus-Oxygen Lyases; C060720:diguanylate cyclase; D006152:Cyclic GMP