Assessing the interspecies and intraspecies diversity of Cas1 and Cas3 proteins of the CRISPR-Cas system in vibrio cholera and Escherichia coli strains

Abstract

Cholera is an extremely virulent waterborne disease caused by the ingestion of food or water contaminated with pathogenic strains of Vibrio cholerae. On the other hand, pathogenic strains of E. coli, particularly Shiga-toxin producing E. coli, are most commonly responsible for diarrheagenic illness, urinary tract infections, as well as life-threatening complications such as Hemolytic Uremic Syndrome (HUS). The presence of the CRISPR-Cas system in both of the bacterial species have raised major global concerns regarding the enhanced chances of pathogenicity or virulence in the bacterial strains due to this adaptive immune system. Besides, the presence of the CRISPR-Cas system within these species can interfere with the emerging phage therapy treatment approaches against drug-resistant bacteria. In this study, we aimed to assess the diversity of cas1 and cas3 protein sequences in the CRISPR locus of several CRISPR confirmed V. cholerae and E. coli strains, and characterize this diversity across the functional domains of the reference cas proteins. Moreover, we established the interspecies relatedness of both species in terms of their cas1 and cas3 sequences.