CRISPR-Cas system: diversity and regulation in Enterobacteriaceae supplementarydata

Insights into the arms race between bacteria and invading mobile genetic elements have revealed the

intricacies of the clustered regularly interspaced short palindromic repeats (CRISPR)-Cas system and the

counter-defenses of bacteriophages. Incredible spacer diversity but significant spacer conservation among

species/subspecies dictates the specificity of the CRISPR-Cas system. Researchers have exploited this

feature to type/subtype the bacterial strains, devise targeted antimicrobials and regulate gene expression.

This review focuses on the nuances of the CRISPR-Cas systems in Enterobacteriaceae that predominantly

harbor type I-E and I-F CRISPR systems. We discuss the systems’ regulation by the global regulators, H-NS,

LeuO, LRP, cAMP receptor protein and other regulators in response to environmental stress. We further

discuss the regulation of noncanonical functions like DNA repair pathways, biofilm formation, quorum

sensing and virulence by the CRISPR-Cas system. The review comprehends multiple facets of the CRISPR-Cas

system in Enterobacteriaceae including its diverse attributes, association with genetic features, regulation

and gene regulatory mechanisms.