title: A conserved tandem cyclophilin-binding site in hepatitis C virus nonstructural protein 5A regulates Alisporivir susceptibility.
abstract: Cyclophilin A (CyPA) and its peptidyl-prolyl isomerase (PPIase) activity play an essential role in hepatitis C virus (HCV) replication, and mounting evidence indicates that nonstructural protein 5A (NS5A) is the major target of CyPA. However, neither a consensus CyPA-binding motif nor specific proline substrates that regulate CyPA dependence and sensitivity to cyclophilin inhibitors (CPIs) have been defined to date. We systematically characterized all proline residues in NS5A domain II, low-complexity sequence II (LCS-II), and domain III with both biochemical binding and functional replication assays. A tandem cyclophilin-binding site spanning domain II and LCS-II was identified. The first site contains a consensus sequence motif of AØPXW (where Ø is a hydrophobic residue) that is highly conserved in the majority of the genotypes of HCV (six of seven; the remaining genotype has VØPXW). The second tandem site contains a similar motif, and the ØP sequence is again conserved in six of the seven genotypes. Consistent with the similarity of their sequences, peptides representing the two binding motifs competed for CyPA binding in a spot-binding assay and induced similar chemical shifts when bound to the active site of CyPA. The two prolines (P310 and P341 of Japanese fulminant hepatitis 1 [JFH-1]) contained in these motifs, as well as a conserved tryptophan in the spacer region, were required for CyPA binding, HCV replication, and CPI resistance. Together, these data provide a high-resolution mapping of proline residues important for CyPA binding and identify critical amino acids modulating HCV susceptibility to the clinical CPI Alisporivir.
authors.affiliation: Department of Biological Science, Florida State University, Tallahassee, Florida, USA.
authors.forename: Henry
authors.initials: H
authors.lastname: Grisé
authors.forename: Stephen
authors.initials: S
authors.lastname: Frausto
authors.forename: Timothy
authors.initials: T
authors.lastname: Logan
authors.forename: Hengli
authors.initials: H
authors.lastname: Tang
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001665:Binding Sites; D002460:Cell Line; D017124:Conserved Sequence; D021984:Cyclophilin A / Q000378:metabolism*; D016572:Cyclosporine / Q000494:pharmacology*; D024882:Drug Resistance, Viral / Q000235:genetics; D005838:Genotype; D016174:Hepacivirus / Q000187:drug effects*; D006801:Humans; D008969:Molecular Sequence Data; D055232:Proline-Rich Protein Domains; D011485:Protein Binding; D011487:Protein Conformation; D020080:Tandem Repeat Sequences; D017361:Viral Nonstructural Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012324:RNA-Dependent RNA Polymerase
chemical_list: D021984:Cyclophilin A; D016572:Cyclosporine; D017361:Viral Nonstructural Proteins; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase; C499715:alisporivir