A novel family of tyrosine integrases encoded by the temperate pleolipovirus SNJ2

作者：Wang, Jiao; Liu, Yingchun; Liu, Ying; Du, Kaixin; Xu, Shuqi; Wang, Yuchen; Krupovic, Mart; Chen, Xiangdong^*

来源：Nucleic Acids Research, 2018, 46(5): 2521-2536.

DOI：10.1093/nar/gky005

• SITE-SPECIFIC RECOMBINATION
• MULTIPLE SEQUENCE ALIGNMENT
• SACCHAROMYCES-CEREVISIAE
• MOBILE ELEMENTS
• SSV1 INTEGRASE
• EXCISIVE RECOMBINATION
• BACTERIOPHAGE-LAMBDA
• VIRION ARCHITECTURE
• NUCLEOTIDE-SEQUENCE
• PLEOMORPHIC VIRUSES

Genomes of halophilic archaea typically contain multiple loci of integrated mobile genetic elements (MGEs). Despite the abundance of these elements, however, mechanisms underlying their site-specific integration and excision have not been investigated. Here, we identified and characterized a novel recombination system encoded by the temperate pleolipovirus SNJ2, which infects haloarchaeon Na-trinema sp. J7-1. SNJ2 genome is inserted into the tRNAMet gene and flanked by 14 bp direct repeats corresponding to attachment core sites. We showed that SNJ2 encodes an integrase (Int(SNJ2)) that excises the proviral genome from its host cell chromosome, but requires two small accessory proteins, Orf2 andOrf3, for integration. These proteins were co-transcribed with Int(SNJ2) to form an operon. Homology searches showed that Int(SNJ2)-type integrases are widespread in haloarchaeal genomes and are associated with various integrated MGEs. Importantly, we confirmed that SNJ2-like recombination systems are encoded by haloarchaea from three different genera and are critical for integration and excision. Finally, phylogenetic analysis suggested that Int(SNJ2)-type recombinases belong to a novel family of archaeal integrases distinct from previously characterized recombinases, including those from the archaeal SSV- and pNOB8-type families.

• 出版日期2018-3-16
• 单位武汉大学; 病毒学国家重点实验室