title: Contribution of SAM and HD domains to retroviral restriction mediated by human SAMHD1.
abstract: The human SAMHD1 protein is a novel retroviral restriction factor expressed in myeloid cells. Previous work has correlated the deoxynucleotide triphosphohydrolase activity of SAMHD1 with its ability to block HIV-1 and SIV(mac) infection. SAMHD1 is comprised of the sterile alpha motif (SAM) and histidine-aspartic (HD) domains; however the contribution of these domains to retroviral restriction is not understood. Mutagenesis and deletion studies revealed that expression of the sole HD domain of SAMHD1 is sufficient to achieve potent restriction of HIV-1 and SIV(mac). We demonstrated that the HD domain of SAMHD1 is essential for the ability of SAMHD1 to oligomerize by using a biochemical assay. In agreement with previous observations, we mapped the RNA-binding ability of SAMHD1 to the HD domain. We also demonstrated a direct interaction of SAMHD1 with RNA by using enzymatically-active purified SAMHD1 protein from insect cells. Interestingly, we showed that double-stranded RNA inhibits the enzymatic activity of SAMHD1 in vitro suggesting the possibility that RNA from a pathogen might modulate the enzymatic activity of SAMHD1 in cells. By contrast, we found that the SAM domain is dispensable for retroviral restriction, oligomerization and RNA binding. Finally we tested the ability of SAMHD1 to block the infection of retroviruses other than HIV-1 and SIV(mac). These results showed that SAMHD1 blocks infection of HIV-2, feline immunodeficiency virus (FIV), bovine immunodeficiency virus (BIV), Equine infectious anemia virus (EIAV), N-tropic murine leukemia virus (N-MLV), and B-tropic murine leukemia virus (B-MLV).
authors.affiliation: Department of Microbiology and Immunology, Albert Einstein College of Medicine Bronx, NY 10461, USA.
authors.forename: Tommy E
authors.initials: TE
authors.lastname: White
authors.forename: Alberto
authors.initials: A
authors.lastname: Brandariz-Nuñez
authors.forename: Jose Carlos
authors.initials: JC
authors.lastname: Valle-Casuso
authors.forename: Sarah
authors.initials: S
authors.lastname: Amie
authors.forename: Laura
authors.initials: L
authors.lastname: Nguyen
authors.forename: Baek
authors.initials: B
authors.lastname: Kim
authors.forename: Jurgen
authors.initials: J
authors.lastname: Brojatsch
authors.forename: Felipe
authors.initials: F
authors.lastname: Diaz-Griffero
mesh_terms: D002460:Cell Line; D003713:Dendritic Cells / Q000821:virology; D049452:Green Fluorescent Proteins / Q000235:genetics; D057809:HEK293 Cells; D015497:HIV-1 / Q000235:genetics / Q000502:physiology; D015498:HIV-2 / Q000235:genetics / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D016087:Immunodeficiency Virus, Bovine / Q000502:physiology; D016089:Immunodeficiency Virus, Feline / Q000502:physiology; D004860:Infectious Anemia Virus, Equine / Q000502:physiology; D009052:Leukemia Virus, Murine / Q000502:physiology; D008264:Macrophages / Q000821:virology; D020559:Monomeric GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*; D054730:Protein Interaction Domains and Motifs; D017434:Protein Structure, Tertiary; D012330:RNA, Double-Stranded / Q000378:metabolism; D012367:RNA, Viral / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics / Q000502:physiology*; D012192:Retroviridae Infections / Q000821:virology*; D000076106:SAM Domain and HD Domain-Containing Protein 1; D015302:Simian Immunodeficiency Virus / Q000235:genetics / Q000378:metabolism; D020298:U937 Cells
chemical_list: D012330:RNA, Double-Stranded; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D049452:Green Fluorescent Proteins; D000076106:SAM Domain and HD Domain-Containing Protein 1; C484280:SAMHD1 protein, human; D020559:Monomeric GTP-Binding Proteins