Banca de DEFESA: DANIEL CHAVES DE LIMA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : DANIEL CHAVES DE LIMA
DATA : 23/09/2016
HORA: 14:00
LOCAL: Anfiteatro dos Anfíbios - Centro de Biociências
TÍTULO:

Characterization of RadA/Sms from Chromobacterium violaceum and discovery of a new episome

PALAVRAS-CHAVES:

Homologous recombination, RadA/Sms, RecA, Chromobacterium violaceum, plasmid

PÁGINAS: 105
RESUMO:

Chromobacterium violaceum is a ß-proteobacteria commonly found around tropical and subtropical regions throughout the globe. It produces many metabolites with biotechnological properties such as antitumoral peptides, antibiotics and polymers that have potential to replace the oil-based ones. Although it has been extensively studied over the past 40 years, there are many aspects of C. violaceum that remains unclear until today. We have conducted a biochemical study on the homologous recombination (HR) machinery of C. violaceum, mainly in RecA and its paralog, RadA/Sms. We performed in vitro assays from initial and late steps of HR such as D-loop formation and branch migration, respectively, with their corresponding molecular actors and how RadA/Sms influenced each one. We observed cvRadA/Sms influences negatively D-loop formation promoted by cvRecA and through pull-down assay we have observed an interaction between these two proteins. We also observed the DNA-binding preference of cvRadA/Sms and cvRecA and observed that this protein binds preferentially to dsDNA instead ssDNA, unlike cvRecA. No involvement of cvRadA/Sms on branch migration reactions was detected. In this work, we also described, for the first time, the isolation, sequencing and annotation of a new plasmid from C. violaceum, which we named ChVi1 and has 44,236 base pairs, 39 predicted open reading frames (ORFs) and, possibly, two origins of replication. Most of the ORFs codes for hypothetical and structural bacteriophage proteins. By using restriction digestion and Next-generation sequencing (NGS) we also looked for the presence of a similar plasmid in other seven C. violaceum strains isolated from amazon region. Our analysis suggest the presence of a plasmid similar to ChVi1 in two of these strains. The present work describes for the first time a biochemical characterization of RadA/Sms and RecA from C. violaceum which have different roles in HR. Moreover, the discovery of ChVi1 opens a path to further explore C. violaceum’s biology.

MEMBROS DA BANCA:
Externo ao Programa - 2170415 - JORGE ESTEFANO SANTANA DE SOUZA
Externo à Instituição - LEONAM GOMES COUTINHO - IFRN
Interno - 1997012 - RAQUEL CORDEIRO THEODORO
Presidente - 1199127 - SILVIA REGINA BATISTUZZO DE MEDEIROS
Externo à Instituição - SÁVIO TORRES DE FARIAS - UFPB