GGDEF/EAL domains and motility in P.putida: a novel protein involved in motility regulation

HERRERA SEITZ, K Y SHINGLER, V

Rosario, Argentina

Congreso; V Jornadas de SAMIGE (Sociedad Argentina de Microbiología General); 2008

SAMIGE (Sociedad Argentina de Microbiologia General)

GGDEF/EAL domains and motility in P.putida: a novel protein involved in motility regulation Herrera Seitz, K 1 y Shingler, V 2 1.IIB, FCEyN, Univ. Nac. del Mar del Plata 2. Molecular Biology Department, Umeå University, Suecia Chemotaxis allows motile bacteria to respond to chemical gradients and concentrate themselves near the source of nutrients.  Microorganisms belonging to Pseudomonas species are known to be able to grow in a wide variety of substances, including many that are considered environmentally dangerous. Unlike previously characterized chemotactic behaviors in Pseudomonas strains, chemotaxis of P.putida CF600 to methyl phenol was shown to be dependent on its metabolism and did not seem to require a specific chemoreceptor Since in E.coli metabolism-dependent taxis responses are mediated by Aer, a protein closely related to chemoreceptors that contains a FAD-binding PAS domain, we analyzed the P.putida genome in the search of aer-like genes. Three aer-like genes were found, and next to one of them, within the same transcriptional unit, a protein containing PAS-GGDEF-EAL domains was found and called our attention. In the last years GGDEF and EAL domains have been associated to diguanylate cyclase and phosphodiesterase activities, respectively. These enzymatic activities would participate in control of intracellular levels of a recently described second messenger for prokaryotes, c-di-GMP. It is known that levels of c-di-GMP can modify cells behavior and motility, therefore PP2258 was thought to be involved in energy taxis via regulation of intracellular levels of di-c-GMP. To test this hypothesis, in this work biochemical properties of PP2258 were studied using as a first approach over expression of the protein both in E.coli and P.putida and in vivo assays. Null mutants in PP2258 show defects in motility. When over expressed in E.coli or P.putida cells, c-di-GMP levels were notably increased compared to control cells, although accumulation of c-di-GMP was much lower in E.coli than in P.putida extracts. A point mutation in GGDEF domain, which is supposed to be involved in c-di-GMP synthesis, causes a decrease in this accumulation, although does not suppress it. On the other hand, a mutation in EAL domain, which is supposed to be involved in its hydrolysis, led to an even higher c-di-GMP accumulation. Together, these results suggest that PP2258 could have both, diguanylate cyclase and phosphodiesterase activities.