Cas1 and Cas2 From the Type II-C CRISPR-Cas System of Riemerella anatipestifer Are Required for Spacer Acquisition

• Published in: Frontiers in cellular and infection microbiology Vol. 8; p. 195
• Main Authors: He, Yang, Wang, Mingshu, Liu, Mafeng, Huang, Li, Liu, Chaoyue, Zhang, Xin, Yi, Haibo, Cheng, Anchun, Zhu, Dekang, Yang, Qiao, Wu, Ying, Zhao, Xinxin, Chen, Shun, Jia, Renyong, Zhang, Shaqiu, Liu, Yunya, Yu, Yanling, Zhang, Ling
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 12.06.2018
• Subjects: Adaptation, Biological - genetics; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Base Sequence - genetics; Cas1; Cas2; Cellular and Infection Microbiology; Clustered Regularly Interspaced Short Palindromic Repeats - genetics; CRISPR-Associated Proteins - genetics; CRISPR-Associated Proteins - metabolism; CRISPR-Cas; CRISPR-Cas Systems - genetics; DNA, Bacterial - genetics; Escherichia coli - enzymology; Escherichia coli - genetics; Immunity - genetics; Plasmids - genetics; Riemerella - enzymology; Riemerella - genetics; Riemerella anatipestifer; Sequence Deletion - genetics; spacer acquisition; CRISPR-Cas; Cas2; Cas1; spacer acquisition; Riemerella anatipestifer
• ISSN: 2235-2988; 2235-2988
• DOI: 10.3389/fcimb.2018.00195

Clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated (Cas) proteins provide acquired genetic immunity against the entry of mobile genetic elements (MGEs). The immune defense provided by various subtypes of the CRISPR-Cas system has been confirmed and is closely associated with the formation of immunological memory in CRISPR arrays, called CRISPR adaptation or spacer acquisition. However, whether type II-C CRISPR-Cas systems are also involved in spacer acquisition remains largely unknown. This study explores and provides some definitive evidence regarding spacer acquisition of the type II-C CRISPR-Cas system from (RA) CH-2 (RA-CH-2). Firstly, introducing an exogenous plasmid into RA-CH-2 triggered spacer acquisition of RA CRISPR-Cas system, and the acquisition of new spacers led to plasmid instability in RA-CH-2. Furthermore, deletion of or 2 of RA-CH-2 abrogated spacer acquisition and subsequently stabilized the exogenous plasmid, suggesting that both Cas1 and Cas2 are required for spacer acquisition of RA-CH-2 CRISPR-Cas system, consistent with the reported role of Cas1 and Cas2 in type I-E and II-A systems. Finally, assays for studying Cas1 nuclease activity and the interaction of Cas1 with Cas2 contributed to a better understanding of the adaptation mechanism of RA CRISPR-Cas system. This is the first experimental identification of the naïve adaptation of type II-C CRISPR-Cas system.