Viral polymerases replicate and transcribe the genomes of several viruses of global health concern such as Hepatitis C virus (HCV), human immunodeficiency virus (HIV) and Ebola virus. For this reason they are key targets for therapies to treat viral infections. Although there is little sequence similarity across the different types of viral polymerases, all of them present a right-hand shape and certain structural motifs that are highly conserved. These features allow their functional properties to be compared, with the goal of broadly applying the knowledge acquired from studying specific viral polymerases to other viral polymerases about which less is known. Here we review the structural and functional properties of the HCV RNA-dependent RNA polymerase (NS5B) in order to understand the fundamental processes underlying the replication of viral genomes. We discuss recent insights into the process by which RNA replication occurs in NS5B as well as the role that conformational changes play in this process.

The reaction of PbPh 2 Cl 2 with two dissymmetric thiosemicarbazone ligands containing diacetyl 4-methyl-3-thiosemicarbazone and hydrazonepyridine or hydrazonequinoline arms led to four new mononuclear complexes, [PbPh 2 (L)] (1 and 3) and [PbPh 2 Cl(HL)] (2 and 4). Reactions with the hydrazonequinoline ligand strongly depend on the reaction conditions and several unexpected compounds were isolated. At room temperature, in addition to complex 4, the polymeric compound [PbPh 2 Cl 2 CH 3 OH] n (5) was isolated, whereas under heating at reflux a symmetrization took place and a polymer [a]

Hepatitis C virus (HCV) is a global health concern for which there is no vaccine available. The HCV polymerase is responsible for the critical function of replicating the RNA genome of the virus. Transitions between at least two conformations (open and closed) are necessary to allow the enzyme to replicate RNA. In this study, molecular dynamic simulations were initiated from multiple crystal structures to understand the free energy landscape (FEL) explored by the enzyme as it interconverts between these conformations. Our studies reveal the location of distinct states within the FEL as well as the molecular interactions associated with these states. Specific hydrogen bonds appear to play a key role in modulating conformational transitions. This knowledge is essential to elucidate the role of these conformations in replication and may also be valuable in understanding the basis by which this enzyme is inhibited by small molecules. © 2016 Wiley Periodicals, Inc.

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