title: Structure of the zinc-binding domain of an essential component of the hepatitis C virus replicase.
abstract: Hepatitis C virus (HCV) is a human pathogen affecting nearly 3% of the world's population. Chronic infections can lead to cirrhosis and liver cancer. The RNA replication machine of HCV is a multi-subunit membrane-associated complex. The non-structural protein NS5A is an active component of HCV replicase, as well as a pivotal regulator of replication and a modulator of cellular processes ranging from innate immunity to dysregulated cell growth. NS5A is a large phosphoprotein (56-58 kDa) with an amphipathic alpha-helix at its amino terminus that promotes membrane association. After this helix region, NS5A is organized into three domains. The N-terminal domain (domain I) coordinates a single zinc atom per protein molecule. Mutations disrupting either the membrane anchor or zinc binding of NS5A are lethal for RNA replication. However, probing the role of NS5A in replication has been hampered by a lack of structural information about this multifunctional protein. Here we report the structure of NS5A domain I at 2.5-A resolution, which contains a novel fold, a new zinc-coordination motif and a disulphide bond. We use molecular surface analysis to suggest the location of protein-, RNA- and membrane-interaction sites.
authors.affiliation: Laboratory of Virology and Infectious Disease, Center for the Study of Hepatitis C, The Rockefeller University, 1230 York Avenue Box 64, New York, New York 10021, USA.
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Tellinghuisen
authors.forename: Joseph
authors.initials: J
authors.lastname: Marcotrigiano
authors.forename: Charles M
authors.initials: CM
authors.lastname: Rice
mesh_terms: D020816:Amino Acid Motifs; D001665:Binding Sites; D018360:Crystallography, X-Ray; D019281:Dimerization; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism; D016174:Hepacivirus / Q000201:enzymology* / Q000235:genetics; D008958:Models, Molecular; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D012324:RNA-Dependent RNA Polymerase / Q000737:chemistry* / Q000378:metabolism; D017361:Viral Nonstructural Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism*
chemical_list: D004220:Disulfides; D017361:Viral Nonstructural Proteins; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase; D015032:Zinc