| First Author | Sparks JL | Year | 2012 |
| Journal | J Biol Chem | Volume | 287 |
| Issue | 51 | Pages | 42773-83 |
| PubMed ID | 23095756 | Mgi Jnum | J:196213 |
| Mgi Id | MGI:5487477 | Doi | 10.1074/jbc.M112.422444 |
| Citation | Sparks JL, et al. (2012) Human exonuclease 5 is a novel sliding exonuclease required for genome stability. J Biol Chem 287(51):42773-83 |
| abstractText | Previously, we characterized Saccharomyces cerevisiae exonuclease 5 (EXO5), which is required for mitochondrial genome maintenance. Here, we identify the human homolog (C1orf176; EXO5) that functions in the repair of nuclear DNA damage. Human EXO5 (hEXO5) contains an iron-sulfur cluster. It is a single-stranded DNA (ssDNA)-specific bidirectional exonuclease with a strong preference for 5'-ends. After loading at an ssDNA end, hEXO5 slides extensively along the ssDNA prior to cutting, hence the designation sliding exonuclease. However, the single-stranded binding protein human replication protein A (hRPA) restricts sliding and enforces a unique, species-specific 5'-directionality onto hEXO5. This specificity is lost with a mutant form of hRPA (hRPA-t11) that fails to interact with hEXO5. hEXO5 localizes to nuclear repair foci in response to DNA damage, and its depletion in human cells leads to an increased sensitivity to DNA-damaging agents, in particular interstrand cross-linking-inducing agents. Depletion of hEXO5 also results in an increase in spontaneous and damage-induced chromosome abnormalities including the frequency of triradial chromosomes, suggesting an additional defect in the resolution of stalled DNA replication forks in hEXO5-depleted cells. |
