Genomics comparison between CRISPR loci and plasmid in Salmonella enteric

Abstract:

Clustered regularly interspaced short palindromic repeats (CRISPR) is the genetic structure found in most of bacteria and archaea. The function of CRISPR is defending against the invasion of exogenous DNA (plasmid, phage, etc.), preventing heterologous gene transfer. [Objective] This study is to study the structural differences of CRISPR loci in several Salmonella sp.[Methods] The molecular structure of CRISPR and the relationship between CRISPR and plasmid was analyzed in 30 strains, including Salmonella gallinarum, S. typhimurium, S. choleraesuis and S. enteritidis by bioinformatics.[Results] CRISPR structure existed in the 30 strains of Salmonella, totally 61 conformed CRISPR loci and 12 possible ones. Neither repeat sequence nor cas1 gene could be used for the classification of these strains.[Conclusion] Although the number of CRISPR loci and spacer sequence have no statistical relationship with the number of plasmid, the spacer sequence has genetic homology with plasmid, transposons, integron and resistant genes. This suggests that Salmonella sp. are attacked by exogenous genes constantly during evolution, and CRISPR loci of Salmonella sp. play a role in resisting exogenous genes.