Abstract
The mammalian thymine DNA glycosylase (TDG) excises 5-carboxylcytosine (5caC) when paired with a guanine in a CpG sequence, in addition to mismatched bases. Here we present a complex structure of the human TDG catalytic mutant, asparagine 140 to alanine (N140A), with a 28-base pair DNA containing a G:5caC pair at pH 4.6. TDG interacts with the carboxylate moiety of target nucleotide 5caC using the side chain of asparagine 230 (N230), instead of asparagine 157 (N157) as previously reported. Mutation of either N157 or N230 residues to aspartate has minimal effect on G:5caC activity while significantly reducing activity on G:U substrate. Combination of both the asparagine-to-aspartate mutations (N157D/N230D) resulted in complete loss of activity on G:5caC while retaining measurable activity on G:U, implying that 5caC can adopt alternative conformations (either N157-interacting or N230-interacting) in the TDG active site to interact with either of the two asparagine side chain for 5caC excision.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
