Structural basis for substrate recognition and processive cleavage mechanisms of the trimeric exonuclease PhoExo I |
| |
| Authors: | Ken-ichi Miyazono Sonoko Ishino Kanae Tsutsumi Tomoko Ito Yoshizumi Ishino Masaru Tanokura |
| |
| Institution: | 1.Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan;2.Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, and Faculty of Agriculture, Kyushu University, Fukuoka, Japan |
| |
| Abstract: | Nucleases play important roles in nucleic acid processes, such as replication, repair and recombination. Recently, we identified a novel single-strand specific 3′-5′ exonuclease, PfuExo I, from the hyperthermophilic archaeon Pyrococcus furiosus, which may be involved in the Thermococcales-specific DNA repair system. PfuExo I forms a trimer and cleaves single-stranded DNA at every two nucleotides. Here, we report the structural basis for the cleavage mechanism of this novel exonuclease family. A structural analysis of PhoExo I, the homologous enzyme from P. horikoshii OT3, showed that PhoExo I utilizes an RNase H-like active site and possesses a 3′-OH recognition site ∼9 Å away from the active site, which enables cleavage at every two nucleotides. Analyses of the heterotrimeric and monomeric PhoExo I activities showed that trimerization is indispensable for its processive cleavage mechanism, but only one active site of the trimer is required. |
| |
| Keywords: | |
|
|
