Stick of Sticks: Structural Features of the Amyloidogenic Peptide-DNA Complex

The search for peptides that can specifically bind to regulatory regions in DNA is a necessary step for creating drugs that can regulate gene expression. The study is dedicated to the peculiarities of binding of a model peptide, which carries an ionic self-complementary motif and can form amyloid-like fibrils [1], with model double-stranded DNAs. The stoichiometric ratios of the components of the complex were found using the retardation method in agarose gel. Using microscale thermophoresis, it was shown that the peptide in the amyloid-like state is capable of binding to model 45-bp double-stranded DNA, with a micromolar equilibrium dissociation constant. Using cryo-electron, transmission electron, and atomic force microscopy, the morphology of peptide-DNA complexes was studied. Using dynamic light scattering and nanoparticle tracking analysis, as well as small-angle neutron scattering, the spatial parameters of the resulting DNA-peptide complexes were characterized. Molecular dynamics simulations showed that the arginine side chains of the peptide are prone to interact with guanine nitrogenous bases. It was shown that the formation of peptide-dsDNA complexes interferes with the operation of restriction endonucleases that have guanine-cytosine pairs in the recognition center, which is consistent with the results of prediction of interaction sites obtained using computer modeling. The results of the work can be used in the development of peptides capable of interacting with functional regions of DNA, as well as in the development of new carriers for transfection of DNA constructs.