Effects of ion concentration on the interaction dengue virus's NS3-ssARN

LEILA A. CABABIE; J. JEREMÍAS INCICCO; LEOPOLDO G. GEBHARD; ANDREA V. GAMARNIK; RODOLFO M. GONZÁLEZ-LEBRERO; SERGIO B. KAUFMAN

Salto, Uruguay

Congreso; Latin American Crosstalk in Biophysics and Physiology; 2015

The dengue virus´s NS3 protein is a helicase that catalyzes the hydrolysis ofATP and couples the free energy of this reaction to drive translocation onsingle strands and unwinding double strands of RNA. Most protein-nucleicacid interactions are extremely sensitive to the concentration of salts insolution. This is because linear nucleic acids are highly charged polyanionsand as a result sequester cations in their vicinity in order to reduce the netcharge on the nucleic acid. It has been postulated that association constant(K obs ) for protein-nucleic acid interaction decreases with increase saltconcentration. Binding protein-nucleic acid is potentiated by the increaseentropy originate for the ions release to free solution 1 .In this work we studied the effect of cations on the interaction betweenDENV NS3 and ssRNA. We performed titration curves NS3 / RNA in thepresence of different concentrations of K + , Na + and Mg 2+ using a fluorescent10 base-RNA oligonucleotide. In all cases, we observed that K obs decreaseswith salt concentration. We could analyse our results with Manningtheory[1] and obtein the number of ions release from the ssRNA in thereaction.1, Manning, G. S. Quarterly reviews of biophysics, 11(02), 179-246, 1978