4cc9

Crystal structure of human SAMHD1 (amino acid residues 582-626) bound to Vpx isolated from sooty mangabey and human DCAF1 (amino acid residues 1058-1396)Crystal structure of human SAMHD1 (amino acid residues 582-626) bound to Vpx isolated from sooty mangabey and human DCAF1 (amino acid residues 1058-1396)

Structural highlights 4cc9 is a 3 chain structure with sequence from Civ and Human. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: , Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Disease [SAMH1_HUMAN] Defects in SAMHD1 are the cause of Aicardi-Goutieres syndrome type 5 (AGS5) [MIM:612952]. A form of Aicardi-Goutieres syndrome, a genetically heterogeneous disease characterized by cerebral atrophy, leukoencephalopathy, intracranial calcifications, chronic cerebrospinal fluid (CSF) lymphocytosis, increased CSF alpha-interferon, and negative serologic investigations for common prenatal infection. Clinical features as thrombocytopenia, hepatosplenomegaly and elevated hepatic transaminases along with intermittent fever may erroneously suggest an infective process. Severe neurological dysfunctions manifest in infancy as progressive microcephaly, spasticity, dystonic posturing and profound psychomotor retardation. Death often occurs in early childhood. Defects in SAMHD1 are the cause of chilblain lupus type 2 (CHBL2) [MIM:614415]. A rare cutaneous form of lupus erythematosus. Affected individuals present with painful bluish-red papular or nodular lesions of the skin in acral locations precipitated by cold and wet exposure at temperatures less than 10 degrees centigrade. Function [VPRBP_HUMAN] Component of the CUL4A-RBX1-DDB1-VprBP/DCAF1 E3 ubiquitin-protein ligase complex, VprBP/DCAF1 may function as the substrate recognition module within this complex. For example, VprBP/DCAF1 targets NF2 to the E3 ubiquitin-ligase complex for ubiquitination and subsequent proteasome-dependent degradation. In case of infection by HIV-1 virus, it is recruited by HIV-1 Vpr in order to hijack the CUL4A-RBX1-DDB1 function leading to arrest the cell cycle in G2 phase, and also to protect the viral protein from proteasomal degradation by another E3 ubiquitin ligase. In case of infection by HIV-2 virus, it is recruited by HIV-2 Vpx in order to hijack the CUL4A-RBX1-DDB1 function leading to enhanced efficiency of macrophage infection and promotion of the replication of cognate primate lentiviruses in cells of monocyte/macrophage lineage. Associated with chromatin in a DDB1-independent and cell cycle-dependent manner, VprBP/DCAF1 is recruited to chromatin as DNA is being replicated and is released from chromatin before mitosis. [SAMH1_HUMAN] Putative nuclease involved in innate immune response by acting as a negative regulator of the cell-intrinsic antiviral response. May play a role in mediating proinflammatory responses to TNF-alpha signaling. [VPX_SIVSP] Plays a role in nuclear translocation of the viral pre-integration complex (PIC), thus is required for the virus to infect non-dividing cells. Targets specific host proteins for degradation by the 26S proteasome. Acts by associating with the cellular CUL4A-DDB1 E3 ligase complex through direct interaction with host VPRPB/DCAF-1. This change in the E3 ligase substrate specificity results in the degradation of host SAMHD1. In turn, SAMHD1 depletion allows viral replication in host myeloid cells by preventing SAMHD1-mediated hydrolysis of intracellular dNTPs necessary for reverse transcription. Publication Abstract from PubMed Lentiviruses contain accessory genes that have evolved to counteract the effects of host cellular defence proteins that inhibit productive infection. One such restriction factor, SAMHD1, inhibits human immunodeficiency virus (HIV)-1 infection of myeloid-lineage cells as well as resting CD4+ T cells by reducing the cellular deoxynucleoside 5'-triphosphate (dNTP) concentration to a level at which the viral reverse transcriptase cannot function. In other lentiviruses, including HIV-2 and related simian immunodeficiency viruses (SIVs), SAMHD1 restriction is overcome by the action of viral accessory protein x (Vpx) or the related viral protein r (Vpr) that target and recruit SAMHD1 for proteasomal degradation. The molecular mechanism by which these viral proteins are able to usurp the host cell's ubiquitination machinery to destroy the cell's protection against these viruses has not been defined. Here we present the crystal structure of a ternary complex of Vpx with the human E3 ligase substrate adaptor DCAF1 and the carboxy-terminal region of human SAMHD1. Vpx is made up of a three-helical bundle stabilized by a zinc finger motif, and wraps tightly around the disc-shaped DCAF1 molecule to present a new molecular surface. This adapted surface is then able to recruit SAMHD1 via its C terminus, making it a competent substrate for the E3 ligase to mark for proteasomal degradation. The structure reported here provides a molecular description of how a lentiviral accessory protein is able to subvert the cell's normal protein degradation pathway to inactivate the cellular viral defence system. Structural basis of lentiviral subversion of a cellular protein degradation pathway.,Schwefel D, Groom HC, Boucherit VC, Christodoulou E, Walker PA, Stoye JP, Bishop KN, Taylor IA Nature. 2013 Dec 15. doi: 10.1038/nature12815. PMID:24336198 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Serine/threonine protein kinase 3D structures VprBP

spinqualitylabelsall models 4cc9, resolution 2.47Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image