Research progress of archaeal RecJ protein

Abstract:

RecJ proteins, the members of aspartate-histidine-histidine (DHH) superfamily of phosphoesterases, are ubiquitous in bacteria, eukaryotes, and archaea. In bacteria, the archetypal RecJ protein is a 5′→3′ ssDNA exonuclease that functions in biological processes such as mismatch repair, homologous recombination, and base excision repair. Cell division cycle 45 (Cdc45) protein, a homologue of bacterial RecJ nuclease, is essential in eukaryotes, but has no nuclease activity. Cdc45 protein forms Cdc45-MCM-GINS (CMG) complex with minichromosome maintenance (MCM) and Go-Ichi-Ni-Sa (GINS), and the complex plays a key role in DNA replication in eukaryotes. Almost all archaea whose genomes have been sequenced encode one or more RecJ protein homologues. Unlike bacterial RecJ nuclease, archaeal RecJ protein has diverse nuclease activities and can form a complex with MCM and GINS which shows functions similar to eukaryotic CMG complex. Thus, archaeal RecJ protein is an important component that is involved in archaeal DNA replication, repair and recombination. Based on current reports on archaeal RecJ protein, this study reviewed the activities, structures, and functions of archaeal RecJ protein, focusing on similarities and differences between different archaeal RecJ proteins and between archaeal RecJ proteins and bacterial RecJ nucleases/eukaryotic RecJ homologues. In addition, we summarized the research trends in archaeal RecJ protein.