View source for 6dw3


==SAMHD1 Bound to Cytarabine-TP in the Catalytic Pocket==
<StructureSection load='6dw3' size='340' side='right'caption='[[6dw3]], [[Resolution|resolution]] 2.20&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6dw3]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6DW3 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6DW3 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.2&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=DTP:2-DEOXYADENOSINE+5-TRIPHOSPHATE'>DTP</scene>, <scene name='pdbligand=GTP:GUANOSINE-5-TRIPHOSPHATE'>GTP</scene>, <scene name='pdbligand=HF4:4-amino-1-{5-O-[(S)-hydroxy{[(R)-hydroxy(phosphonooxy)phosphoryl]oxy}phosphoryl]-beta-D-arabinofuranosyl}pyrimidin-2(1H)-one'>HF4</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=6dw3 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6dw3 OCA], [https://pdbe.org/6dw3 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6dw3 RCSB], [https://www.ebi.ac.uk/pdbsum/6dw3 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6dw3 ProSAT]</span></td></tr>
</table>
== Disease ==
[https://www.uniprot.org/uniprot/SAMH1_HUMAN SAMH1_HUMAN] Defects in SAMHD1 are the cause of Aicardi-Goutieres syndrome type 5 (AGS5) [MIM:[https://omim.org/entry/612952 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.<ref>PMID:19525956</ref> <ref>PMID:20842748</ref>   Defects in SAMHD1 are the cause of chilblain lupus type 2 (CHBL2) [MIM:[https://omim.org/entry/614415 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.<ref>PMID:21204240</ref> 
== Function ==
[https://www.uniprot.org/uniprot/SAMH1_HUMAN 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.<ref>PMID:18546154</ref> <ref>PMID:19525956</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
SAMHD1 is a deoxynucleoside triphosphate triphosphohydrolase (dNTPase) that depletes cellular dNTPs in noncycling cells to promote genome stability and to inhibit retroviral and herpes viral replication. In addition to being substrates, cellular nucleotides also allosterically regulate SAMHD1 activity. Recently, it was shown that high expression levels of SAMHD1 are also correlated with significantly worse patient responses to nucleotide analog drugs important for treating a variety of cancers, including acute myeloid leukemia (AML). In this study, we used biochemical, structural, and cellular methods to examine the interactions of various cancer drugs with SAMHD1. We found that both the catalytic and the allosteric sites of SAMHD1 are sensitive to sugar modifications of the nucleotide analogs, with the allosteric site being significantly more restrictive. We crystallized cladribine-TP, clofarabine-TP, fludarabine-TP, vidarabine-TP, cytarabine-TP, and gemcitabine-TP in the catalytic pocket of SAMHD1. We found that all of these drugs are substrates of SAMHD1 and that the efficacy of most of these drugs is affected by SAMHD1 activity. Of the nucleotide analogs tested, only cladribine-TP with a deoxyribose sugar efficiently induced the catalytically active SAMHD1 tetramer. Together, these results establish a detailed framework for understanding the substrate specificity and allosteric activation of SAMHD1 with regard to nucleotide analogs, which can be used to improve current cancer and antiviral therapies.

The structural basis for cancer drug interactions with the catalytic and allosteric sites of SAMHD1.,Knecht KM, Buzovetsky O, Schneider C, Thomas D, Srikanth V, Kaderali L, Tofoleanu F, Reiss K, Ferreiros N, Geisslinger G, Batista VS, Ji X, Cinatl J Jr, Keppler OT, Xiong Y Proc Natl Acad Sci U S A. 2018 Oct 10. pii: 1805593115. doi:, 10.1073/pnas.1805593115. PMID:30305425<ref>PMID:30305425</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 6dw3" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Batista VS]]
[[Category: Buzovetsky O]]
[[Category: Cinatl J]]
[[Category: Ferreiros N]]
[[Category: Geisslinger G]]
[[Category: Ji X]]
[[Category: Kaderali L]]
[[Category: Keppler OT]]
[[Category: Knecht KM]]
[[Category: Reiss K]]
[[Category: Schneider C]]
[[Category: Srikanth V]]
[[Category: Thomas D]]
[[Category: Tofoleanu F]]
[[Category: Xiong Y]]