Structural highlights
FunctionEXOG_HUMAN Endo/exonuclease with nicking activity towards supercoiled DNA, a preference for single-stranded DNA and 5'-3' exonuclease activity.[1] Publication Abstract from PubMedHuman EXOG (hEXOG) is a 5'-exonuclease that is crucial for mitochondrial DNA repair; the enzyme belongs to a nonspecific nuclease family that includes the apoptotic endonuclease EndoG. Here we report biochemical and structural studies of hEXOG, including structures in its apo form and in a complex with DNA at 1.81 and 1.85 A resolution, respectively. A Wing domain, absent in other betabetaalpha-Me members, suppresses endonuclease activity, but confers on hEXOG a strong 5'-dsDNA exonuclease activity that precisely excises a dinucleotide using an intrinsic 'tape-measure'. The symmetrical apo hEXOG homodimer becomes asymmetrical upon binding to DNA, providing a structural basis for how substrate DNA bound to one active site allosterically regulates the activity of the other. These properties of hEXOG suggest a pathway for mitochondrial BER that provides an optimal substrate for subsequent gap-filling synthesis by DNA polymerase gamma. A domain in human EXOG converts apoptotic endonuclease to DNA-repair exonuclease.,Szymanski MR, Yu W, Gmyrek AM, White MA, Molineux IJ, Lee JC, Yin YW Nat Commun. 2017 May 3;8:14959. doi: 10.1038/ncomms14959. PMID:28466855[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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