TY - JOUR
T1 - Discrimination of lesion removal of N-methylpurine-DNA glycosylase revealed by a potent neutralizing monoclonal antibody
AU - Adhikari, Sanjay
AU - Kennel, Stephen J.
AU - Roy, Gargi
AU - Mitra, Partha S.
AU - Mitra, Sankar
AU - Roy, Rabindra
PY - 2008/1/1
Y1 - 2008/1/1
N2 - N-Methylpurine-DNA glycosylase (MPG), a ubiquitous DNA repair enzyme, initiates excision repair of several N-alkylpurine adducts, induced by alkylating chemotherapeutics, and deaminated and lipid peroxidation-induced purine adducts. We have generated monoclonal antibodies (moAbs) against human MPG. Twelve independent hybridoma clones were characterized, which, except 520-16A, are identical based on epitope exclusion assay. Four moAbs, including 520-2A, 520-3A, 520-16A, and 520-26A, have high affinity (KD ∼ 0.3-1.6 nM), and their subtypes were IgG2a, IgG1, IgG2a, and IgG2b, respectively. moAb 520-3A recognizes the sequence 52AQAPCPRERCLGPP66T, an epitope exclusively present in the N-terminal extension of human MPG. We found that moAb 520-3A significantly inhibited MPG's enzymatic activity towards different substrates, such as hypoxanthine, 1,N6ethenoadenine and methylated bases, which represent different classes of DNA damage, however, with different efficiencies. Real-time binding experiments using surface plasmon resonance (SPR) spectroscopy showed that the pronounced inhibition of activity was not in the substrate-binding step. Single turnover kinetics (STO) revealed that the inhibition was at the catalytic step. Since we found that this antibody has an epitope in the N-terminal tail, the latter appears to have an important role in substrate discrimination, however, with a differential effect on different substrates.
AB - N-Methylpurine-DNA glycosylase (MPG), a ubiquitous DNA repair enzyme, initiates excision repair of several N-alkylpurine adducts, induced by alkylating chemotherapeutics, and deaminated and lipid peroxidation-induced purine adducts. We have generated monoclonal antibodies (moAbs) against human MPG. Twelve independent hybridoma clones were characterized, which, except 520-16A, are identical based on epitope exclusion assay. Four moAbs, including 520-2A, 520-3A, 520-16A, and 520-26A, have high affinity (KD ∼ 0.3-1.6 nM), and their subtypes were IgG2a, IgG1, IgG2a, and IgG2b, respectively. moAb 520-3A recognizes the sequence 52AQAPCPRERCLGPP66T, an epitope exclusively present in the N-terminal extension of human MPG. We found that moAb 520-3A significantly inhibited MPG's enzymatic activity towards different substrates, such as hypoxanthine, 1,N6ethenoadenine and methylated bases, which represent different classes of DNA damage, however, with different efficiencies. Real-time binding experiments using surface plasmon resonance (SPR) spectroscopy showed that the pronounced inhibition of activity was not in the substrate-binding step. Single turnover kinetics (STO) revealed that the inhibition was at the catalytic step. Since we found that this antibody has an epitope in the N-terminal tail, the latter appears to have an important role in substrate discrimination, however, with a differential effect on different substrates.
KW - Base excision repair
KW - Epitope mapping
KW - Inhibition
KW - MPG
KW - Substrate specificity
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U2 - 10.1016/j.dnarep.2007.07.012
DO - 10.1016/j.dnarep.2007.07.012
M3 - Article
C2 - 17768096
AN - SCOPUS:36549048414
VL - 7
SP - 31
EP - 39
JO - DNA Repair
JF - DNA Repair
SN - 1568-7864
IS - 1
ER -