Cloning and Mutagenesis of an Iron-Citrate Receptor (Feca) Gene Homolog in Xanthomonas Campestris Pathovar Vesicatoria

The plant pathogen Xanthomonas campestris pathovar vesicatoria is the cause of bacterial spot disease, a common infection of pepper and tomato plants resulting in significant leaf damage and crop loss. The genome of Xanthomonas campestris pathovar vesicatoria strain 85-10 has recently been sequenced and made publicly available. This gram negative bacterium, like most living organisms, requires iron as an essential element for its survival. Many gram-negative organisms use similar mechanisms for iron uptake. This includes secretion and reuptake of ferric-specific chelators, or siderophores, through the use of several inner and outer membrane proteins. Through the use of bioinformatics tools, we assessed that Xanthomonas campestris pathovar vesicatoria strain 85-10 contains sequences homologous to siderophore biosynthesis and siderophore uptake genes from other gram-negative bacteria. This research focused on a putative gene with homology to a family of TonB-dependent outer-membrane iron receptors in other Gram-negative organisms. It is adjacent to a putative siderophore biosynthesis operon, but is not predicted to be in the same operon. We have cloned a large fragment of this gene and are in the process of creating a ?knock-out? mutant in order to observe if a functional deletion of the gene impairs the organism's ability to acquire iron and to infect its natural host.