N-terminus of the rat adenine glycosylase MYH affects excision rates and processing of MYH-generated abasic sites

AUTOR(ES)

Ma, Huaxian

FONTE

Oxford University Press

RESUMO

Repair of most modified and mispaired bases in the genome is initiated by DNA glycosylases, which bind to their respective targets and cleave the N-glycosyl bond to initiate base excision repair (BER). The mammalian homolog of the Escherichia coli MutY DNA glycosylase (MYH) cleaves adenine residues paired with either oxidized or non-modified guanines. MYH is crucial for the avoidance of mutations resulting from oxidative DNA damage. Multiple N-terminal splice variants of MYH exist in mammalian cells and it is likely that different variants result in the production of enzymes with altered properties. To investigate whether modifications in the N-terminus are consequential to MYH function, we overexpressed intact and N-terminal-deletion rat MYH proteins and examined their activities. We found that deletion of 75 amino acids, which perturbs the catalytic core that is conserved with E.coli MutY, abolished excision activity. In contrast, deletions limited to the extended mammalian N-terminal domain, differentially influenced steady-state excision rates. Notably, deletion of 50 amino acids resulted in an enzyme with a significantly lower Km favoring formation of excision products with 3′-OH termini. Our findings suggest that MYH isoforms divergent in the N-terminus influence excision rates and processing of abasic sites.

Documentos Relacionados

• The major form of MeCP2 has a novel N-terminus generated by alternative splicing
• Interaction between the N-terminus of human topoisomerase I and SV40 large T antigen.
• Key role of the N-terminus of chicken annexin A5 in vesicle aggregation
• Identification of two functional regions in Fis: the N-terminus is required to promote Hin-mediated DNA inversion but not lambda excision.
• N-Terminus Conservation in the Terminal Pigment of Phycobilisomes from a Prokaryotic and Eukaryotic Alga 1