Sandbox Reserved 1102: Difference between revisions
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== Function == | == Function == | ||
Zika is | Zika is a [https://en.wikipedia.org/wiki/Double-stranded_RNA_viruses double-stranded RNA virus]. The [https://en.wikipedia.org/wiki/Viral_replication genome replication] of double-Stranded RNA virus need intervention of [https://en.wikipedia.org/wiki/Helicase helicase]. | ||
Protein from Zika consists of a protease domain at its [https://en.wikipedia.org/wiki/N-terminus N terminus] and a helicase domain at its [https://en.wikipedia.org/wiki/C-terminus C terminus]. The multifunctional helicase, belonging to the superfamily 2 (SF2) helicase family, is an essential enzyme involved in the cycles of [https://en.wikipedia.org/wiki/ATP_hydrolysis ATP hydrolysis] and behaves as a motor protein in RNA unwinding | Protein from Zika consists of a protease domain at its [https://en.wikipedia.org/wiki/N-terminus N terminus] and a helicase domain at its [https://en.wikipedia.org/wiki/C-terminus C terminus]. The multifunctional helicase, belonging to the superfamily 2 (SF2) helicase family, is an essential enzyme involved in the cycles of [https://en.wikipedia.org/wiki/ATP_hydrolysis ATP hydrolysis] and behaves as a motor protein in RNA unwinding helicase domain that has 5'-triphosphatase activity of Zika performs the critical and indispensable function of unwinding double-stranded RNA during Zika genome replication. Helicase performs ATP hydrolysis at the 5′ end of RNA to generate energy. The phosphorus atom of the γ-phosphate group of the ATP molecule is attacked by water molecule; then, the γ-phosphate group is released with ADP. With the use of the energy derived from ATP hydrolysis, helicase translocates along nucleic acid strands, unwinds the double-stranded RNA genome. | ||
[[Image:ATPhydrolysis.jpg | thumb | upright=3,5 | Energy from ATP hydrolysis]] | [[Image:ATPhydrolysis.jpg | thumb | upright=3,5 | Energy from ATP hydrolysis]] | ||
Which is an essential step for viral RNA replication. It then provides conditions for the polymerization of RNA by an RNA-dependent RNA polymerase and the methylation of RNA by methyltransferase, which is crucial for Zika replication (13). In addition, it has been reported that the ATPase activity could alter viral replicative capacity and efficiency and consequently change the host innate immune response . | Which is an essential step for viral RNA replication. It then provides conditions for the polymerization of RNA by an RNA-dependent RNA polymerase and the methylation of RNA by methyltransferase, which is crucial for Zika replication (13). In addition, it has been reported that the ATPase activity could alter viral replicative capacity and efficiency and consequently change the host innate immune response . | ||
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The helicase active site has a serine residue that serves as a nucleophilic amino acid. This residue is essential for the catalytic activity of the enzyme.The serine protases present a catalytic triad composed of 3 amino acids His57 Asp102 and Ser195.These 3 amino acids have a specific interaction which is due to the folding of the protein. The tridimentional conformation of the protein brings closer these 3 residues. Their side chains have a specific function : | The helicase active site has a serine residue that serves as a nucleophilic amino acid. This residue is essential for the catalytic activity of the enzyme.The serine protases present a catalytic triad composed of 3 amino acids His57 Asp102 and Ser195.These 3 amino acids have a specific interaction which is due to the folding of the protein. The tridimentional conformation of the protein brings closer these 3 residues. Their side chains have a specific function : | ||
[[Image:Serine protease catalysis.png | thumb | upright= | [[Image:Serine protease catalysis.png | thumb | upright=3 | Serine protease catalysis]] | ||
'''Ser195''': the hydroxyl group plays the role of a nucleophile that attack the substrate. | '''Ser195''': the hydroxyl group plays the role of a nucleophile that attack the substrate. | ||
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All these reactions allows to cleave the substrate by attacking its carbonyl group. | All these reactions allows to cleave the substrate by attacking its carbonyl group. | ||
There are two ligands for zika helicase : ADP and Manganese II ion | There are two ligands for zika helicase : ADP and Manganese II ion | ||
-ADP | |||
-Manganese II ion | |||
