Persistent
infection with
hepatitis C virus (HCV) is a major cause of
chronic liver diseases. The aim of this study was to identify
host cell factor(s) participating in the HCV replication complex (RC) and to clarify the regulatory mechanisms of viral genome replication dependent on the host-derived factor(s) identified. By comparative
proteome analysis of RC-rich membrane fractions and subsequent
gene silencing mediated by
RNA interference, we identified several candidates for RC components involved in HCV replication. We found that one of these candidates,
creatine kinase B (CKB), a key ATP-generating
enzyme that regulates ATP in
subcellular compartments of nonmuscle cells, is important for efficient replication of the HCV genome and propagation of infectious
virus. CKB interacts with HCV NS4A protein and forms a complex with NS3-4A, which possesses multiple
enzyme activities. CKB upregulates both NS3-4A-mediated unwinding of
RNA and
DNA in vitro and
replicase activity in permeabilized HCV replicating cells. Our results support a model in which recruitment of CKB to the HCV RC compartment, which has high and fluctuating energy demands, through its interaction with NS4A is important for efficient replication of the viral genome. The CKB-NS4A association is a potential target for the development of a new type of
antiviral therapeutic strategy.
