Identification of FBL2 As a Geranylgeranylated Cellular Protein Required for Hepatitis C Virus RNA Replication

• DOI: 10.1016/j.molcel.2005.04.004
• Publication Date: 2005-06-01T14:26:35Z
• Authors: Chunfu Wang; Michael Gale; Brian C. Keller; Hua Huang; Michael S. Brown; Joseph L. Goldstein; Jin Ye
• Keywords: 0301 basic medicine; 0303 health sciences; F-Box Proteins; Mevalonic Acid; Cell Cycle Proteins; Cell Biology; Hepacivirus; Viral Nonstructural Proteins; Tritium; Cell Line; 3. Good health; 03 medical and health sciences; Humans; RNA, Viral; Diterpenes; Molecular Biology; West Nile virus

We recently reported that Hepatitis C virus (HCV) RNA replication requires one or more geranylgeranylated host proteins. Using a combination of [(3)H]mevalonate labeling, coimmunoprecipitation, and bioinformatic search, we identified a geranylgeranylated host protein required for HCV RNA replication. This protein, FBL2, contains an F box domain and a CAAX motif (CVIL). It forms a stable immunoprecipitable complex with the HCV nonstructural protein 5A (NS5A). The association of FBL2 with NS5A requires the CAAX motif of FBL2, but not the F box. Deletion of the F box created a dominant-negative protein that inhibited replication of HCV RNA when overexpressed in Huh7-K2040 cells; this inhibition was overcome by coexpression of NS5A. siRNA-mediated knockdown of FBL2 mRNA by 70% in Huh7-HP cells reduced HCV RNA by 65%; this reduction was overcome by expression of a cDNA encoding a wobble mutant of FBL2. The current data indicate that geranylgeranylated FBL2 binds to NS5A in a reaction crucial for HCV RNA replication.