Novel ATP-Independent RNA Annealing Activity of the Dengue Virus NS3 Helicase

The flavivirus nonstructural protein 3 (NS3) bears multiple enzymatic activities and represents an attractive target for antiviral intervention. NS3 contains the viral serine protease at the N-terminus and ATPase, RTPase, and helicase activities at the C-terminus. These activities are essential for...

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Main Authors:	Gebhard, Leopoldo G., Kaufman, Sergio B., Gamarnik, Andrea V.
Format:	Online
Language:	English
Published:	Public Library of Science 2012
Online Access:	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3340334/

id	pubmed-3340334
recordtype	oai_dc
spelling	pubmed-33403342012-05-03 Novel ATP-Independent RNA Annealing Activity of the Dengue Virus NS3 Helicase Gebhard, Leopoldo G. Kaufman, Sergio B. Gamarnik, Andrea V. Research Article The flavivirus nonstructural protein 3 (NS3) bears multiple enzymatic activities and represents an attractive target for antiviral intervention. NS3 contains the viral serine protease at the N-terminus and ATPase, RTPase, and helicase activities at the C-terminus. These activities are essential for viral replication; however, the biological role of RNA remodeling by NS3 helicase during the viral life cycle is still unclear. Secondary and tertiary RNA structures present in the viral genome are crucial for viral replication. Here, we used the NS3 protein from dengue virus to investigate functions of NS3 associated to changes in RNA structures. Using different NS3 variants, we characterized a domain spanning residues 171 to 618 that displays ATPase and RNA unwinding activities similar to those observed for the full-length protein. Interestingly, we found that, besides the RNA unwinding activity, dengue virus NS3 greatly accelerates annealing of complementary RNA strands with viral or non-viral sequences. This new activity was found to be ATP-independent. It was determined that a mutated NS3 lacking ATPase activity retained full-RNA annealing activity. Using an ATP regeneration system and different ATP concentrations, we observed that NS3 establishes an ATP-dependent steady state between RNA unwinding and annealing, allowing modulation of the two opposing activities of this enzyme through ATP concentration. In addition, we observed that NS3 enhanced RNA-RNA interactions between molecules representing the ends of the viral genome that are known to be necessary for viral RNA synthesis. We propose that, according to the ATP availability, NS3 could function regulating the folding or unfolding of viral RNA structures. Public Library of Science 2012-04-30 /pmc/articles/PMC3340334/ /pubmed/22558403 http://dx.doi.org/10.1371/journal.pone.0036244 Text en Gebhard et al. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
repository_type	Open Access Journal
institution_category	Foreign Institution
institution	US National Center for Biotechnology Information
building	NCBI PubMed
collection	Online Access
language	English
format	Online
author	Gebhard, Leopoldo G. Kaufman, Sergio B. Gamarnik, Andrea V.
spellingShingle	Gebhard, Leopoldo G. Kaufman, Sergio B. Gamarnik, Andrea V. Novel ATP-Independent RNA Annealing Activity of the Dengue Virus NS3 Helicase
author_facet	Gebhard, Leopoldo G. Kaufman, Sergio B. Gamarnik, Andrea V.
author_sort	Gebhard, Leopoldo G.
title	Novel ATP-Independent RNA Annealing Activity of the Dengue Virus NS3 Helicase
title_short	Novel ATP-Independent RNA Annealing Activity of the Dengue Virus NS3 Helicase
title_full	Novel ATP-Independent RNA Annealing Activity of the Dengue Virus NS3 Helicase
title_fullStr	Novel ATP-Independent RNA Annealing Activity of the Dengue Virus NS3 Helicase
title_full_unstemmed	Novel ATP-Independent RNA Annealing Activity of the Dengue Virus NS3 Helicase
title_sort	novel atp-independent rna annealing activity of the dengue virus ns3 helicase
description	The flavivirus nonstructural protein 3 (NS3) bears multiple enzymatic activities and represents an attractive target for antiviral intervention. NS3 contains the viral serine protease at the N-terminus and ATPase, RTPase, and helicase activities at the C-terminus. These activities are essential for viral replication; however, the biological role of RNA remodeling by NS3 helicase during the viral life cycle is still unclear. Secondary and tertiary RNA structures present in the viral genome are crucial for viral replication. Here, we used the NS3 protein from dengue virus to investigate functions of NS3 associated to changes in RNA structures. Using different NS3 variants, we characterized a domain spanning residues 171 to 618 that displays ATPase and RNA unwinding activities similar to those observed for the full-length protein. Interestingly, we found that, besides the RNA unwinding activity, dengue virus NS3 greatly accelerates annealing of complementary RNA strands with viral or non-viral sequences. This new activity was found to be ATP-independent. It was determined that a mutated NS3 lacking ATPase activity retained full-RNA annealing activity. Using an ATP regeneration system and different ATP concentrations, we observed that NS3 establishes an ATP-dependent steady state between RNA unwinding and annealing, allowing modulation of the two opposing activities of this enzyme through ATP concentration. In addition, we observed that NS3 enhanced RNA-RNA interactions between molecules representing the ends of the viral genome that are known to be necessary for viral RNA synthesis. We propose that, according to the ATP availability, NS3 could function regulating the folding or unfolding of viral RNA structures.
publisher	Public Library of Science
publishDate	2012
url	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3340334/
_version_	1611525994626154496

Novel ATP-Independent RNA Annealing Activity of the Dengue Virus NS3 Helicase

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