New findings in the biology of Chromobacterium violaceum:
homologous recombination and a new episome
Homologous Recombination, RadA/Sms, RecA, Chromobacterium
violaceum.
Chromobacterium violaceum is a ß-proteobacteria commonly found
around tropical and subtropical regions throughout the globe. This
specie has many metabolites with biotechnological properties such
as antitumoral peptides, antibiotics, polymers that have the potential
to replace the oil-based ones among others. Although it has been
extensively studied the past 40 years, there are many aspects of C.
violaceum that remains untouched until today. We have conducted a
biochemical overview on the homologous recombination (HR)
machinery of C. violaceum, most of the work based mainly in RecA
and its paralog, RadA. We performed in vitro reactions from initial
and late steps from homologous recombination such as D-loop
formation and branch migration, respectively, with their respective
molecular actors and how RadA influenced each one. We observed
that cvRadA influences, negatively, D-loop formation promoted by
cvRecA and from pull-down assay we predicted an interaction
between these two proteins. We also observed the DNA-binding
preference of cvRadA (and cvRecA) and observed that this protein
binds preferentially to dsDNA instead ssDNA, the opposite from cvRecA. No involvement of cvRadA on branch migration reactions
was detected. In this work, we also described the isolation, sequence
and annotation of a new plasmid, never detected before, from C.
violaceum, named ChVi1. It has 44,236 base pairs, 39 predicted
open reading frames and, possibly, two origins of replication. Most of
the ORFs codes for hypothetical and structural bacteriophage
proteins.