Analysis of CRISPR/Cas system of Proteus and the factors affected the functional mechanism.

BACKGROUND: The Proteus is one of the most common human and animal pathogens. Clustered regularly interspaced short palindromic repeats and CRISPR-associated proteins (CRISPR/Cas) are inheritable genetic elements found in a variety of archaea and bacteria in the evolution, providing immune function against foreign invasion. OBJECTIVES: To analyze the characteristics and functions of the CRISPR/Cas system in Proteus genomes, as well as the internal and external factors affecting the system. METHODS: CRISPR loci were identified and divided into groups based on the repeat sequence in 96 Proteus strains by identification. Compared the RNA secondary structure and minimum free energy of CRISPR loci through bioinformatics, the evolution of cas genes, and the effects of related elements were also discussed. RESULTS: 85 CRISPR loci were identified and divided into six groups based on the sequence of repeats, and the more stable the secondary structure of RNA, the smaller the minimum free energy, the fewer base mutations in the repeat, the more stable the CRISPR and the more complete the evolution of the system. In addition, Cas1 gene can be a symbol to distinguish species to some extent. Of all the influencing factors, CRISPR/Cas had the greatest impact on plasmids. CONCLUSIONS: This study examined the diversity of CRISPR/Cas system in Proteus and found statistically significant positive/negative correlations between variety factors (the RNA stability, free energy, etc.) and the CRISPR locus, which played a vital role in regulating the CRISPR/Cas system.