Chromosome segregation in Xanthomonas citri subsp. citri

• Grant number: 12/09252-0
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Effective date (Start): October 01, 2012
• Effective date (End): September 30, 2013
• Field of knowledge: Agronomical Sciences - Agronomy - Plant Health
• Principal Investigator: Henrique Ferreira
• Grantee: Amanda Piovesan Ucci
• Supervisor: Patrick H. Viollier
• Host Institution: Faculdade de Ciências Farmacêuticas (FCFAR). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil
• Research place: Université de Genève, Switzerland
• Associated to the scholarship: 10/02041-8 - Chromosome segregation in Xanthomonas citri subsp. citri, BP.DR

Abstract

Recent data from our group (research grant FAPESP 2010/05099-7 and PhD scholarship 2010/02041-8) showed that ParB encoded by Xanthomonas citri (Xac) is involved with chromosome segregation, and we also noticed the existence of phenotypic similarities between the segregation-cell division processes of Xac and C. crescentus. If our suspicious are correct, Xac may exhibit a control of septation in cell division that is reminiscent of the one documented for C. crescentus, where a factor, not yet identified in Xac, associates with ParB and interferes with septum placement during cell cycle progression. In C. crescentus, this factor was named MipZ, which has as main function the inhibition of FtsZ polymerization in cellular sites other than in the middle of the rods. MipZ function and sub-cellular localization depends on ParB. The mipZ gene was identified in C. crescentus on a screen for parA-like ORFs; Xac also has a handful of ORFs annotated as parA to which function has not been assigned. In order to unveil such relation between the two microorganisms and to verify if Xac had a control of septum placement similar to C. crescentus, we need to knockout/disrupt the parA-like ORFs of the former in an attempt to identify the analogue of mipZ . In addition, we would like to study the influences that the ParA-like proteins encoded by Xac have on ParB function. To achieve this, mutants expressing different combinations of ParB-GFP/parA- or parB-/ParA-GFP will be characterized by advanced techniques of fluorescence microscopy so to detect perturbations of the normal patterns of ParAB subcellular localization. We also intend to identify experimentally the DNA-binding sites of ParB on the main chromosome of Xac, and evaluate the influence of ParA-like proteins on the interaction of ParB with the DNA. These associations will be explored using Deep sequencing/ChIP-seq experiments. The elucidation of such systems and their functions in Xac will contribute not only for the understanding of its biology, but may open a new field of research in the sense that perturbations of ParB in Xac led to a loss of virulence in this plant pathogen (please, se draft of a manuscript in preparation attached). (AU)