Given the known effects of metal ions on the activities of various DNA and RNA polymerases, we tested if metal ions could affect selleck chemical hepadnavirus RT priming. We report here that Mn(2+), in comparison with Mg(2+), showed dramatic effects on the priming activity of MiniRT2 as well as the full-length, RT. First and foremost, MiniRT2 exhibited full polymerization activity in the presence of Mn(2+), indicating that MiniRT2 contains all sequences essential for polymerization but is unable to transition from initiation to polymerization with Mg(2+). Second,

the initiation activities of MiniRT2 and the full-length RT were much stronger with Mn(2+). Third, the nucleotide and template specificities during protein priming were decreased in the presence of Mn(2+). Fourth, polymerization was sensitive to inhibition by a pyrophosphate analog in the presence of Mn(2+) but not in the presence of Mg(2+). Finally, limited proteolysis provided direct evidence that the priming active MiniRT2 adopted distinct conformations depending on the presence of Mn(2+) versus that of Mg(2+) and that the transition from initiation to polymerization was accompanied by RT conformational change.”
“In this study, we establish that cholesterol and sphingolipid associated with hepatitis C virus (HCV) particles

click here are important for virion maturation and infectivity. In a recently developed culture system WZB117 cost enabling study of the complete life cycle of HCV, mature virions were enriched with cholesterol as assessed by the molar ratio of cholesterol to phospholipid in virion and cell membranes. Depletion of cholesterol from the virus or hydrolysis of virion-associated sphingomyelin almost completely abolished HCV infectivity. Supplementation of cholesterol-depleted virus with exogenous cholesterol enhanced infectivity to a level equivalent to that of the untreated control.

Cholesterol-depleted or sphingomyelin-hydrolyzed virus had markedly defective internalization, but no influence on cell attachment was observed. Significant portions of HCV structural proteins partitioned into cellular detergent-resistant, lipid-raft-like membranes. Combined with the observation that inhibitors of the sphingolipid biosynthetic pathway block virion production, but not RNA accumulation, in a JFH-1 isolate, our findings suggest that alteration of the lipid composition of HCV particles might be a useful approach in the design of anti-HCV therapy.”
“Manganese (Mn) is a transition metal that is essential for normal cell growth and development, but is toxic at high concentrations. While Mn deficiency is uncommon in humans, Mn toxicity is known to be readily prevalent due to occupational overexposure in miners, smelters and possibly welders.