| Structural highlights
Disease
[MGME1_HUMAN] Progressive external ophthalmoplegia - myopathy - emaciation. The disease may be caused by mutations affecting the gene represented in this entry.
Function
[MGME1_HUMAN] Metal-dependent single-stranded DNA (ssDNA) exonuclease involved in mitochondrial genome maintenance. Has preference for 5'-3' exonuclease activity but is also capable of endoduclease activity on linear substrates. Necessary for maintenance of proper 7S DNA levels. Probably involved in mitochondrial DNA (mtDNA) repair, possibly via the processing of displaced DNA containing Okazaki fragments during RNA-primed DNA synthesis on the lagging strand or via processing of DNA flaps during long-patch base excision repair. Specifically binds 5-hydroxymethylcytosine (5hmC)-containing DNA in stem cells.[HAMAP-Rule:MF_03030][1] [2]
Publication Abstract from PubMed
Mitochondrial nucleases play important roles in accurate maintenance and correct metabolism of mtDNA, the own genetic materials of mitochondria that are passed exclusively from mother to child. MGME1 is a highly conserved DNase that was discovered recently. Mutations in MGME1-coding gene lead to severe mitochondrial syndromes characterized by external ophthalmoplegia, emaciation, and respiratory failure in humans. Unlike many other nucleases that are distributed in multiple cellular organelles, human MGME1 is a mitochondria-specific nuclease; therefore, it can serve as an ideal target for treating related syndromes. Here, we report one HsMGME1-Mn2+ complex and three different HsMGME1-DNA complex structures. In combination with in vitro cleavage assays, our structures reveal the detailed molecular basis for substrate DNA binding and/or unwinding by HsMGME1. Besides the conserved two-cation-assisted catalytic mechanism, structural analysis of HsMGME1 and comparison with homologous proteins also clarified substrate binding and cleavage directionalities of the DNA double-strand break repair complexes RecBCD and AddAB.
Structural insights into DNA degradation by human mitochondrial nuclease MGME1.,Yang C, Wu R, Liu H, Chen Y, Gao Y, Chen X, Li Y, Ma J, Li J, Gan J Nucleic Acids Res. 2018 Sep 21. pii: 5104735. doi: 10.1093/nar/gky855. PMID:30247721[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Kornblum C, Nicholls TJ, Haack TB, Scholer S, Peeva V, Danhauser K, Hallmann K, Zsurka G, Rorbach J, Iuso A, Wieland T, Sciacco M, Ronchi D, Comi GP, Moggio M, Quinzii CM, DiMauro S, Calvo SE, Mootha VK, Klopstock T, Strom TM, Meitinger T, Minczuk M, Kunz WS, Prokisch H. Loss-of-function mutations in MGME1 impair mtDNA replication and cause multisystemic mitochondrial disease. Nat Genet. 2013 Feb;45(2):214-9. doi: 10.1038/ng.2501. Epub 2013 Jan 13. PMID:23313956 doi:http://dx.doi.org/10.1038/ng.2501
- ↑ Szczesny RJ, Hejnowicz MS, Steczkiewicz K, Muszewska A, Borowski LS, Ginalski K, Dziembowski A. Identification of a novel human mitochondrial endo-/exonuclease Ddk1/c20orf72 necessary for maintenance of proper 7S DNA levels. Nucleic Acids Res. 2013 Mar 1;41(5):3144-61. doi: 10.1093/nar/gkt029. Epub 2013, Jan 28. PMID:23358826 doi:http://dx.doi.org/10.1093/nar/gkt029
- ↑ Yang C, Wu R, Liu H, Chen Y, Gao Y, Chen X, Li Y, Ma J, Li J, Gan J. Structural insights into DNA degradation by human mitochondrial nuclease MGME1. Nucleic Acids Res. 2018 Sep 21. pii: 5104735. doi: 10.1093/nar/gky855. PMID:30247721 doi:http://dx.doi.org/10.1093/nar/gky855
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