ANTIGEN STRUCTURAL REQUIREMENTS FOR RECOGNITION BY A CYCLOBUTANE THYMINE DIMER-SPECIFIC MONOCLONAL-ANTIBODY

A monoclonal antibody (TDM-2) specific to a UV-induced cyclobutane pyr imidine dimer (T[cis-syn]T) has previously been established; however, the immunization had used UV-irradiated calf-thymus DNA containing a h eterogeneous mixture of photoproduct sites. We investigated here the s tructural requirements of antigen recognition by the antibody using ch emically synthesized antigen analogs. TDM-2 bound with cis-syn, but no t trans-syn thymine dimer, and could bind strongly with four nucleotid e analogs in which the cis-syn pyrimidine dimer was located in the cen ter. Antigen analogs containing abasic linkers at the 5'- or 3'-side o f the cis-syn cyclobutane pyrimidine dimer were synthesized and tested for binding to TDM-2. The results indicated that TDM-2 recognizes not only the cyclobutane ring but also both the 5'- and 3'-side nucleosid es of the cyclobutane dimer. Furthermore, it was proved that either th e 5'- or 3'-side phosphate group at a cyclobutane dimer site was absol utely required for the affinity to TDM-2. The antibody showed a strong binding to single stranded DNA but indicated little binding to double stranded DNA.