| Structural highlights
Disease
APTX_HUMAN Defects in APTX are the cause of ataxia-oculomotor apraxia syndrome (AOA) [MIM:208920. AOA is an autosomal recessive syndrome characterized by early-onset cerebellar ataxia, oculomotor apraxia, early areflexia and late peripheral neuropathy.[1] [2] [3] [4] [5] [6] [7]
Function
APTX_HUMAN DNA-binding protein involved in single-strand DNA break repair, double-strand DNA break repair and base excision repair. Resolves abortive DNA ligation intermediates formed either at base excision sites, or when DNA ligases attempt to repair non-ligatable breaks induced by reactive oxygen species. Catalyzes the release of adenylate groups covalently linked to 5'-phosphate termini, resulting in the production of 5'-phosphate termini that can be efficiently rejoined. Also able to hydrolyze adenosine 5'-monophosphoramidate (AMP-NH(2)) and diadenosine tetraphosphate (AppppA), but with lower catalytic activity.[8] [9] [10] [11] [12]
Publication Abstract from PubMed
The failure of DNA ligases to complete their catalytic reactions generates cytotoxic adenylated DNA strand breaks. The APTX RNA-DNA deadenylase protects genome integrity and corrects abortive DNA ligation arising during ribonucleotide excision repair and base excision DNA repair, and APTX human mutations cause the neurodegenerative disorder ataxia with oculomotor ataxia 1 (AOA1). How APTX senses cognate DNA nicks and is inactivated in AOA1 remains incompletely defined. Here, we report X-ray structures of APTX engaging nicked RNA-DNA substrates that provide direct evidence for a wedge-pivot-cut strategy for 5'-AMP resolution shared with the alternate 5'-AMP processing enzymes POLbeta and FEN1. Our results uncover a DNA-induced fit mechanism regulating APTX active site loop conformations and assembly of a catalytically competent active center. Further, based on comprehensive biochemical, X-ray and solution NMR results, we define a complex hierarchy for the differential impacts of the AOA1 mutational spectrum on APTX structure and activity. Sixteen AOA1 variants impact APTX protein stability, one mutation directly alters deadenylation reaction chemistry, and a dominant AOA1 variant unexpectedly allosterically modulates APTX active site conformations.
Mechanism of APTX nicked DNA sensing and pleiotropic inactivation in neurodegenerative disease.,Tumbale P, Schellenberg MJ, Mueller GA, Fairweather E, Watson M, Little JN, Krahn J, Waddell I, London RE, Williams RS EMBO J. 2018 Jun 22. pii: embj.201798875. doi: 10.15252/embj.201798875. PMID:29934293[13]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Date H, Onodera O, Tanaka H, Iwabuchi K, Uekawa K, Igarashi S, Koike R, Hiroi T, Yuasa T, Awaya Y, Sakai T, Takahashi T, Nagatomo H, Sekijima Y, Kawachi I, Takiyama Y, Nishizawa M, Fukuhara N, Saito K, Sugano S, Tsuji S. Early-onset ataxia with ocular motor apraxia and hypoalbuminemia is caused by mutations in a new HIT superfamily gene. Nat Genet. 2001 Oct;29(2):184-8. PMID:11586299 doi:10.1038/ng1001-184
- ↑ Moreira MC, Barbot C, Tachi N, Kozuka N, Uchida E, Gibson T, Mendonca P, Costa M, Barros J, Yanagisawa T, Watanabe M, Ikeda Y, Aoki M, Nagata T, Coutinho P, Sequeiros J, Koenig M. The gene mutated in ataxia-ocular apraxia 1 encodes the new HIT/Zn-finger protein aprataxin. Nat Genet. 2001 Oct;29(2):189-93. PMID:11586300 doi:10.1038/ng1001-189
- ↑ Shimazaki H, Takiyama Y, Sakoe K, Ikeguchi K, Niijima K, Kaneko J, Namekawa M, Ogawa T, Date H, Tsuji S, Nakano I, Nishizawa M. Early-onset ataxia with ocular motor apraxia and hypoalbuminemia: the aprataxin gene mutations. Neurology. 2002 Aug 27;59(4):590-5. PMID:12196655
- ↑ Tranchant C, Fleury M, Moreira MC, Koenig M, Warter JM. Phenotypic variability of aprataxin gene mutations. Neurology. 2003 Mar 11;60(5):868-70. PMID:12629250
- ↑ Le Ber I, Moreira MC, Rivaud-Pechoux S, Chamayou C, Ochsner F, Kuntzer T, Tardieu M, Said G, Habert MO, Demarquay G, Tannier C, Beis JM, Brice A, Koenig M, Durr A. Cerebellar ataxia with oculomotor apraxia type 1: clinical and genetic studies. Brain. 2003 Dec;126(Pt 12):2761-72. Epub 2003 Sep 23. PMID:14506070 doi:10.1093/brain/awg283
- ↑ Criscuolo C, Mancini P, Menchise V, Sacca F, De Michele G, Banfi S, Filla A. Very late onset in ataxia oculomotor apraxia type I. Ann Neurol. 2005 May;57(5):777. PMID:15852392 doi:10.1002/ana.20463
- ↑ Quinzii CM, Kattah AG, Naini A, Akman HO, Mootha VK, DiMauro S, Hirano M. Coenzyme Q deficiency and cerebellar ataxia associated with an aprataxin mutation. Neurology. 2005 Feb 8;64(3):539-41. PMID:15699391 doi:10.1212/01.WNL.0000150588.75281.58
- ↑ Sano Y, Date H, Igarashi S, Onodera O, Oyake M, Takahashi T, Hayashi S, Morimatsu M, Takahashi H, Makifuchi T, Fukuhara N, Tsuji S. Aprataxin, the causative protein for EAOH is a nuclear protein with a potential role as a DNA repair protein. Ann Neurol. 2004 Feb;55(2):241-9. PMID:14755728 doi:10.1002/ana.10808
- ↑ Gueven N, Becherel OJ, Kijas AW, Chen P, Howe O, Rudolph JH, Gatti R, Date H, Onodera O, Taucher-Scholz G, Lavin MF. Aprataxin, a novel protein that protects against genotoxic stress. Hum Mol Genet. 2004 May 15;13(10):1081-93. Epub 2004 Mar 25. PMID:15044383 doi:10.1093/hmg/ddh122
- ↑ Kijas AW, Harris JL, Harris JM, Lavin MF. Aprataxin forms a discrete branch in the HIT (histidine triad) superfamily of proteins with both DNA/RNA binding and nucleotide hydrolase activities. J Biol Chem. 2006 May 19;281(20):13939-48. Epub 2006 Mar 16. PMID:16547001 doi:M507946200
- ↑ Ahel I, Rass U, El-Khamisy SF, Katyal S, Clements PM, McKinnon PJ, Caldecott KW, West SC. The neurodegenerative disease protein aprataxin resolves abortive DNA ligation intermediates. Nature. 2006 Oct 12;443(7112):713-6. Epub 2006 Sep 10. PMID:16964241 doi:10.1038/nature05164
- ↑ Rass U, Ahel I, West SC. Actions of aprataxin in multiple DNA repair pathways. J Biol Chem. 2007 Mar 30;282(13):9469-74. Epub 2007 Feb 2. PMID:17276982 doi:M611489200
- ↑ Tumbale P, Schellenberg MJ, Mueller GA, Fairweather E, Watson M, Little JN, Krahn J, Waddell I, London RE, Williams RS. Mechanism of APTX nicked DNA sensing and pleiotropic inactivation in neurodegenerative disease. EMBO J. 2018 Jun 22. pii: embj.201798875. doi: 10.15252/embj.201798875. PMID:29934293 doi:http://dx.doi.org/10.15252/embj.201798875
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