Monoclonal antibodies specific for poly(dG).cntdot.poly(dC) and poly(dG).cntdot.poly(dm5C)

Publisher Website
Google Scholar
Abstract
Most duplex DNAs that are in the "B" conformation are not immunogenic. One important exception is poly(dG).cntdot.poly(dC), which produces a good immune response even though, by many criteria, it adopts a conventional right-handed helix. In order to investigate what features are being recognized, monoclonal antibodies were prepared against poly(dG).cntdot.poly(dC) and the related polymer poly(dG).cntdot.poly(dm5C). Jel 72, which is an IgG, binds only to poly(dG).cntdot.poly(dC), while Jel 68, which is an IgM, binds .apprx. 10-fold more strongly to poly(dG).cntdot.poly(dm5C) than to poly(dG).cntdot.poly(dC). For both antibodies, no significant interaction could be detected with any other synthetic DNA duplexes including poly[d(Gm5C)].cntdot.poly[d(Gm5C)] in both the "B" and "Z" forms, poly[d(Tm5Cm5C)].cntdot.poly[d(GGA)], and poly[d(TCC)].cntdot.poly[d(GGA)], poly(dI).cntdot.poly(dC), or poly(dI).cntdot.poly(dm5C). The binding to poly(dG).cntdot.poly(dC) was inhibited by ethidium and by disruption of the DNA duplex, confirming that the antibodies were not recognizing single-stranded or multistranded structures. Furthermore, Jel 68 binds significantly to phage XP-12 DNA, which contains only m5C residues and will precipitate this DNA in the absence of a 2nd antibody. The results suggest that (dG)n.cntdot.(dm5C)n sequences in natural DNA exist in recognizably distinct conformations.