Template-directed design of a DNA-DNA cross-linker based upon a bis-tomaymycin-duplex adduct.
A template-directed approach to the design of a DNA-DNA interstrand cross-linker based upon the structure of a bis-tomaymycin-duplex adduct has been carried out. Tomaymycin is a member of the pyrrolo[1,4]benzodiazepines antitumor antibiotics. In a previous study (F.L. Boyd et al., Biochemistry 1990, 29, 2387-2403), we have shown that two tomaymycin molecules can be covalently bound to a 12-mer duplex molecule, where the drug molecules are on opposite strands six base-pairs apart, and the stereochemistry at the drug bonding site, and orientation in the minor groove, was defined by high-field NMR. This bis-tomaymycin 12-mer duplex adduct maintains the self-complementarity of the duplex and a B-type structure. In the present study we have shown using high-field NMR that this same 12-mer sequence can be truncated by two base pairs so that the two tomaymycin-modified guanines are now only four base-pairs apart, the two species of tomaymycin molecules are still bound with the same stereochemistry and orientation, and the 10-mer duplex adduct maintains its self-complementarity. In a second 10-mer duplex we have shown that changing the bonding sequence from 5'CGA to 5'AGC does not significantly affect the structure of the bis-tomaymycin-duplex adduct. However, when the sequence is rearranged so that the drugs point in a tail-to-tail orientation rather than in the previous head-to-head configuration, there are more than one species of tomaymycin bound to DNA, and, as a consequence, the bis-tomaymycin 10-mer duplex adduct loses its self-complementarity. Last, we have used the 10-mer duplex containing the 5'CGA sequence, in which the tomaymycin molecules are oriented head to head, to design an interstrand cross-linking species in which the two drug molecules are linked together with a flexible linker molecule.
Wang
J J
JJ
College of Pharmacy, Drug Dynamics Institute, University of Texas, Austin 78712.
Hill
G C
GC
Hurley
L H
LH
D001483:Base Sequence; D001570:Benzodiazepinones / Q000737:chemistry / Q000494:pharmacology; D003198:Computer Simulation; D003432:Cross-Linking Reagents / Q000737:chemistry / Q000494:pharmacology*; D004247:DNA / Q000737:chemistry / Q000187:drug effects*; D015195:Drug Design; D006147:Guanine / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D013698:Templates, Genetic
D001570:Benzodiazepinones; D003432:Cross-Linking Reagents; C003619:tomaymycin; D006147:Guanine; D004247:DNA