title: TBC1D20 is a Rab1 GTPase-activating protein that mediates hepatitis C virus replication.
abstract: Like other viruses, productive hepatitis C virus (HCV) infection depends on certain critical host factors. We have recently shown that an interaction between HCV nonstructural protein NS5A and a host protein, TBC1D20, is necessary for efficient HCV replication. TBC1D20 contains a TBC (Tre-2, Bub2, and Cdc16) domain present in most known Rab GTPase-activating proteins (GAPs). The latter are master regulators of vesicular membrane transport, as they control the activity of membrane-associated Rab proteins. To better understand the role of the NS5A-TBC1D20 interaction in the HCV life cycle, we used a biochemical screen to identify the TBC1D20 Rab substrate. TBC1D20 was found to be the first known GAP for Rab1, which is implicated in the regulation of anterograde traffic between the endoplasmic reticulum and the Golgi complex. Mutation of amino acids implicated in Rab GTPase activation by other TBC domain-containing GAPs abrogated the ability of TBC1D20 to activate Rab1 GTPase. Overexpression of TBC1D20 blocked the transport of exogenous vesicular stomatitis virus G protein from the endoplasmic reticulum, validating the involvement of TBC1D20 in this pathway. Rab1 depletion significantly decreased HCV RNA levels, suggesting a role for Rab1 in HCV replication. These results highlight a novel mechanism by which viruses can hijack host cell machinery and suggest an attractive model whereby the NS5A-TBC1D20 interaction may promote viral membrane-associated RNA replication.
authors: Department of Medicine, Division of Gastroenterology and Hepatology, Stanford University School of Medicine, Palo Alto, CA 94305-5187, USA.
authors: Ella H
authors: EH
authors: Sklan
authors: Ramon L
authors: RL
authors: Serrano
authors: Shirit
authors: S
authors: Einav
authors: Suzanne R
authors: SR
authors: Pfeffer
authors: David G
authors: DG
authors: Lambright
authors: Jeffrey S
authors: JS
authors: Glenn
mesh_terms: D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000235:genetics / Q000378:metabolism / Q000821:virology; D004789:Enzyme Activation / Q000502:physiology; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism*; D006056:Golgi Apparatus / Q000235:genetics / Q000378:metabolism / Q000821:virology; D016174:Hepacivirus / Q000502:physiology*; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D012367:RNA, Viral / Q000096:biosynthesis* / Q000235:genetics; D014759:Viral Envelope Proteins / Q000235:genetics / Q000378:metabolism; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000378:metabolism; D014779:Virus Replication / Q000502:physiology*; D020761:rab1 GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D012324:RNA-Dependent RNA Polymerase
chemical_list: D020690:GTPase-Activating Proteins; D008562:Membrane Glycoproteins; D012367:RNA, Viral; D014759:Viral Envelope Proteins; D017361:Viral Nonstructural Proteins; D020761:rab1 GTP-Binding Proteins; C028391:G protein, vesicular stomatitis virus; C526344:TBC1D20 protein, human; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase