High-temperature protein G is essential for activity of the Escherichia coli clustered regularly interspaced short palindromic repeats (CRISPR)/Cas system

• Published in: Proceedings of the National Academy of Sciences - PNAS 2011-12, Vol.108 (50), p.20136-20141
• Main Authors: Yosef, Ido, Goren, Moran G, Kiro, Ruth, Edgar, Rotem, Qimron, Udi
• Format: Article
• Language: English
• Subjects: adaptive immunity; Bacteria; bacterial proteins; Bacteriophages; Biological Sciences; Deoxyribonucleic acid; DNA; E coli; Escherichia coli; Escherichia coli - genetics; Escherichia coli - metabolism; Escherichia coli - virology; Escherichia coli Proteins - genetics; Escherichia coli Proteins - metabolism; G-proteins; Gene Expression Regulation, Bacterial; Genes, Bacterial - genetics; Genetic screening; Genetic Testing; Heat shock proteins; High temperature; Hot Temperature; HSP90 Heat-Shock Proteins - genetics; HSP90 Heat-Shock Proteins - metabolism; Inverted Repeat Sequences - genetics; Libraries; Mutation - genetics; Plasmids; Plasmids - genetics; Prokaryotes; prokaryotic cells; Prophages; Prophages - metabolism; Reproducibility of Results; RNA; screening; Transposons
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1113519108

Prokaryotic DNA arrays arranged as clustered regularly interspaced short palindromic repeats (CRISPR), along with their associated proteins, provide prokaryotes with adaptive immunity by RNA-mediated targeting of alien DNA or RNA matching the sequences between the repeats. Here, we present a thorough screening system for the identification of bacterial proteins participating in immunity conferred by the Escherichia coli CRISPR system. We describe the identification of one such protein, high-temperature protein G (HtpG), a homolog of the eukaryotic chaperone heat-shock protein 90. We demonstrate that in the absence of htpG, the E. coli CRISPR system loses its suicidal activity against λ prophage and its ability to provide immunity from lysogenization. Transcomplementation of htpG restores CRISPR activity. We further show that inactivity of the CRISPR system attributable to htpG deficiency can be suppressed by expression of Cas3, a protein that is essential for its activity. Accordingly, we also find that the steady-state level of overexpressed Cas3 is significantly enhanced following HtpG expression. We conclude that HtpG is a newly identified positive modulator of the CRISPR system that is essential for maintaining functional levels of Cas3.