Campylobacter jejuni genomes exhibit notable GC variation within housekeeping genes

Abstract

Campylobacter jejuni(C. jejuni) is a rapidly evolving bacterial species with massive genetic recombination potential to generate niche specific genotypes. Generally the housekeeping gene lineage has been evidenced to undergo lateral gene transfer and recombination quite frequently compared to the information processing gene lineage. During such exchanges, genetic amelioration takes place over time acquiring the host genomes’ molecular characteristics. In this study, fifty genes that comprised twenty five metabolic housekeeping lineage genes and twenty five information processing lineage genes from nineteenC. jejunigenomes were studied. These nineteen genomes included sevenC. jejuniisolates that belonged to the same genotype or multilocus sequence type ST-474 that were sequences in New Zealand. The genes from both lineages were tested for recombination and the guanine-cytosine (GC) variation. There was a positive correlation between the GC variance and the number of recombination events amongst the metabolic housekeeping genes. Genes that showed wider GC variance had a relatively high number of recombination events. In contrast, although recombination was evident in all of the informational genes, there was no correlation between the GC variance and recombination. The observation of a positive correlation between the GC variance and the recombination events in the metabolic housekeeping genes may reflect the recent events of exchange of DNA and the regions that are constantly dynamic to undergo recombination under certain circumstances. While in the case of informational genes, the demand of stringent homology between genes may be a limiting factor for the absence of such correlation, however, the sites that involved in recombination may also represent the hotspots of recombination in those genes.