Nucleotide specificity in the presence of RNA by dengue virus NS3 helicase

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

Villa Carlos Paz, Córdoba

Congreso; XLII Reunión Anual de la Sociedad Argentina de Biofísica; 2013

The dengue virus genome encodes a polyprotein which is cleaved by peptidases to give three structuraland seven non-structural (NS) proteins. Among these the NS3 protein presents the characteristic featuresof helicases.This protein moves along single strands and unwinds double strands of RNA moleculesdriven by the binding and hydrolysis of nucleosides triphosphates (NTPs). It is known that this enzymecatalyzes the hydrolysis of several NTPs and this activity is enhanced by the presence of single strandedRNA. We have previously studied the specificity of NS3 for nucleotides ATP, GTP, CTP and UTP in theabsence of RNA and now we examine how this specificity is affected by the presence of RNA. For thispurpose we obtained the substrate curves for the four nucleotides mentioned in the presence of poly(A).In all cases it was observed lower K M and higher k cat values than in absence of RNA. According to thevalue of the specificity parameter (k cat / K M ) we obtained the following specificity order: ATP> GTP> CTP>UTP.