Aprataxin (APTX) (APTX)

Aprataxin (APTX) is a nuclear enzyme encoded by the APTX gene in humans, primarily involved in the repair of single-stranded DNA breaks through its ability to remove 5'-adenylate (5'-AMP) groups from DNA ends left after abortive DNA ligation events, particularly during non-homologous end joining, base excision repair, and ribonucleotide excision repair[1][2][3]. This function is critical for maintaining genomic stability. Aprataxin contains a histidine triad (HIT) domain with nucleotide hydrolase activity and a C2HE zinc finger domain, which together enable it to sense and resolve DNA nicks and adenylated DNA termini[2][4]. Mutations in APTX lead to ataxia with oculomotor apraxia type 1 (AOA1), an autosomal recessive neurodegenerative disorder characterized by progressive cerebellar ataxia, oculomotor apraxia, and peripheral neuropathy, likely due to accumulated unrepaired DNA strand breaks in the nervous system[1][3][6]. In vitro and in vivo studies suggest that aprataxin deficiency may also contribute to features of premature aging and increased sensitivity to oxidative stress[1][6]. Aprataxin interacts with key DNA repair proteins, including PARP1, p53, XRCC1, and XRCC4, indicating a role in coordinating the DNA damage response[1][6]. Structurally, aprataxin employs a "wedge-pivot-cut" mechanism to distort DNA at nicks and position the 5'-AMP lesion into its active site for hydrolysis[2][4]. Despite its critical role in DNA repair, aprataxin is not currently a direct target of approved therapeutic drugs, and no drugs are known to interact specifically with this enzyme. Its importance as a potential biomarker for AOA1 or other neurodegenerative conditions has not been established, and no notable therapeutic challenges or safety concerns have been reported, likely due to its disease association being primarily through loss-of-function mutations rather than overactivity[1][3].

Other names

AXA1FHA-HITFLJ20157AOAAOA1EAOHEOAHAforkhead-associated domain histidine triad-like proteinAprataxin