Xylella fastidiosa quorum sensing: role of DSF on stress responses regulation and bacterial population control

Abstract

Genome sequencing has generated a huge amount of information. However, there is still an immediate need of studies to uncover the functions of the genes that have been identified in such projects. Functional genome studies must include approaches that have a focus on both, the wide coverage of the genome and also the function of particular genes. One aspect comprised by the studies o four group in the functional genomics of Xylella fastidiosa was the expression of genes associated with the pathogenicity of the bacterium, based on the hypothesis that the formation of biofilm is essential for the establishment of the bacterium and the colonization of the xylem. However, one of the major problems for the development of the research on the pathogenicity of X. fastidiosa, was always the difficulty of obtaining knockout mutants for the pathogenic strains. We recently verified (Young Researcher Project 04/14576-2) that the biofilm of X. fastidiosa is more resistant to antimicrobial compounds than the planktonic form. That analysis demonstrated that the resistance is a complex phenomenon that cannot be explained by only one mechanism but by several factors that could comprise different resistance mechanisms as the enlargement of the biofilm because of the production of EPS and the expression of specific genes. It is possible that cellular signalization or quorum sensing is involved in the activation of the mechanisms for cellular self-protection. Recent studies indicate that the perception of DSF is basic for the activation of several genes in X. fastidiosa, including those involved in plant virulence and acquisition by the insect vector. Even though the studies on X. fastidiosa DSF have shown important progresses, there is no report on the role of this molecule in the stress response of the biofilm. Therefore, this project aims to evaluate the role of DSF during the biofilm formation and also in the molecular signalization under stress conditions. Moreover, it is proposed to test synthetic analogs of DSF as potential inhibitor agent in the biofilm formation of X. fastidiosa. In the face of the exposed above this "new frontiers" project has the objective of not only developing the proposed project but also gaining knowledge on strategies for knocking out specific genes of X. fastidiosa pathogenic strains, homologous recombination genes fused with GFP, the technology for biosensor development, and also learning new strategies for control OPF the disease using signalization molecules, developed by the group of Dr. Steven Lindow (University of California - Berkeley). In addition to that, I look for establishing strong collaborations with external researchers with high scientific recognition in the area in which the project is inserted. (AU)