Helicase and Annealing Activities of Dengue Virus Non-Structural Protein 3 on Dengue genome 5’ and 3’ UTR
|關鍵字:||登革熱;非結構性蛋白;解旋酶;非轉譯區;dengue virus;non-structural protein;helicase;untranslated region|
Outside of the long ORF of dengue virus, highly structured untranslated regions are found at both the 5’ and 3’ ends. In addition to local secondary structures, complementary sequences were found in 5’ and 3’ UTR which are able to induce long range interactions. It is believed that dengue genome exist in two forms during different replication stages: a linear form with local secondary structures on each ends of the genome or a circular form with the 5’ and 3’ UTR forming a duplex. Non-structural protein 3, NS3, contains a trypsin-like serine protease domain within the N-terminal domain. Moreover, NS3, on its C-terminal region, has a DExH family helicase which is responsible for separating nascent genome strand from the template. In addition, NS3Helicase have been suggested a novel role, which is the modulator of genome structures as it could unwind secondary structures within the UTR to promote genome circularization and vice versa. In our study, we expressed and purified dengue NS3-Helicase. We also constructed expression vector for NS2B-NS3 and NS2B-NS3protease, however, the results of expression and purification of these recombinant proteins were undesirable. Simple DNA annealing reactions were carried out using purified NS3-Helicase, yet, no sign of any annealing activity was observed. Further investigation will be needed to uncover the cause.