title: Niemann-Pick C1 (NPC1)/NPC1-like1 chimeras define sequences critical for NPC1's function as a flovirus entry receptor.
abstract: We recently demonstrated that Niemann-Pick C1 (NPC1), a ubiquitous 13-pass cellular membrane protein involved in lysosomal cholesterol transport, is a critical entry receptor for filoviruses. Here we show that Niemann-Pick C1-like1 (NPC1L1), an NPC1 paralog and hepatitis C virus entry factor, lacks filovirus receptor activity. We exploited the structural similarity between NPC1 and NPC1L1 to construct and analyze a panel of chimeras in which NPC1L1 sequences were replaced with cognate sequences from NPC1. Only one chimera, NPC1L1 containing the second luminal domain (C) of NPC1 in place of its own, bound to the viral glycoprotein, GP. This engineered protein mediated authentic filovirus infection nearly as well as wild-type NPC1, and more efficiently than did a minimal NPC1 domain C-based receptor recently described by us. A reciprocal chimera, NPC1 containing NPC1L1&#8217;s domain C, was completely inactive. Remarkably, an intra-domain NPC1L1-NPC1 chimera bearing only a &#126;130-amino acid N&#8211;terminal region of NPC1 domain C could confer substantial viral receptor activity on NPC1L1. Taken together, these findings account for the failure of NPC1L1 to serve as a filovirus receptor, highlight the central role of the luminal domain C of NPC1 in filovirus entry, and reveal the direct involvement of N&#8211;terminal domain C sequences in NPC1&#8217;s function as a filovirus receptor.
authors.affiliation: Department of Microbiology and Immunology, Albert Einstein College of Medicine, 1300 Morris Park Ave, Bronx, NY 10461, USA. anuja@immindia.org
authors.forename: Anuja
authors.initials: A
authors.lastname: Krishnan
authors.forename: Emily Happy
authors.initials: EH
authors.lastname: Miller
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Herbert
authors.forename: Melinda
authors.initials: M
authors.lastname: Ng
authors.forename: Esther
authors.initials: E
authors.lastname: Ndungo
authors.forename: Sean P
authors.initials: SP
authors.lastname: Whelan
authors.forename: John M
authors.initials: JM
authors.lastname: Dye
authors.forename: Kartik
authors.initials: K
authors.lastname: Chandran
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D016563:Filoviridae / Q000502:physiology*; D006801:Humans; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000378:metabolism*; D008969:Molecular Sequence Data; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs / Q000502:physiology; D011991:Receptors, Virus / Q000378:metabolism*; D016415:Sequence Alignment; D014759:Viral Envelope Proteins / Q000378:metabolism; D053586:Virus Internalization
chemical_list: D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D011991:Receptors, Virus; D014759:Viral Envelope Proteins; C113189:envelope glycoprotein, Ebola virus