Parallel Structures Formed by T,C-rich Sequences. psDNA-MvaI Endonuclease Interactions
Formation of alternative DNA structures, such as parallel-stranded (ps) DNA may have important biological implications, for example, in view of specific DNA-protein interactions. The location of groups of atoms of heterocyclic bases in the grooves of ps- and aps- (antiparallel-stranded) DNA is quite different thus providing different modes of recognition by DNA operating proteins.
Four oligonucleotides (A-D) of non-regular heteropyrimidine sequences incorporating or not purine residues can form self-associated parallel-stranded (ps) structures at acidic pH. The ps structures were identified by studying at neutral and acidic pH UV melting transitions, FTIR spectra, and fluorescence of pyrene-labeled oligonucleotides.
We have studied the interaction of the MvaI restriction endonuclease with oligonucleotides B and D. The parallel structures B and D are not cleaved by MvaI,but it is shown that a 50-fold excess of ps duplex B almost completely inhibits the hydrolysis of the canonical substrate by MvaI. Duplex A, which does not contain the MvaI recognition site does not influence cleavage of the canonical substrate. It is shown, that MvaI endonuclease does not cleave the parallel structures containing parallel MvaI recognition site, but is able to bind to one of them.
Frederic Geinguenaud, Jean Liquier, Maxim G. Brevnov, Olga V. Petrauskene, Yakov, Alexeev, Elizaveta S. Gromova , Eliane Taillandier
Laboratoire de Spectroscopie Biomoléculaire, UPRES-A CNRS 7031,