TY - JOUR
T1 - A putative cyclin-binding motif in human SAMHD1 contributes to protein phosphorylation, localization, and stability
AU - Gelais, Corine St
AU - Kim, Sun Hee
AU - Ding, Lingmei
AU - Yount, Jacob S.
AU - Ivanov, Dmitri
AU - Spearman, Paul
AU - Wu, Li
N1 - Funding Information:
This work was supported by National Institutes of Health Grants GM111027 (to P. S.) and AI104483, CA181997, AI120209, and AI127667 (to L. W.) and in part by the Public Health Preparedness for Infectious Diseases Program of the Ohio State University (to L. W.). The authors declare that they have no conflicts of interest with the contents of this article. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
PY - 2016/12/16
Y1 - 2016/12/16
N2 - SAMHD1 (sterile α motif and HD domain-containing protein 1) is a mammalian protein that regulates intracellular dNTP levels through its hydrolysis of dNTPs. SAMHD1 functions as an important retroviral restriction factor through a mechanism relying on its dNTPase activity. We and others have reported that human SAMHD1 interacts with the cell cycle regulatory proteins cyclin A, CDK1, and CDK2, which mediates phosphorylation of SAMHD1 at threonine 592, a post-translational modification that has been implicated in abrogating SAMHD1 restriction function and ability to form stable tetramers. Utilizing co-immunoprecipitation and colocalization approaches, we show that endogenous SAMHD1 is able to interact with the cyclin A-CDK1-CDK2 complex in monocytic THP-1 cells and primary monocyte-derived macrophages. Sequence analysis of SAMHD1 identifies a putative cyclin-binding motif found in many cyclin-CDK complex substrates. Using a mutagenesis-based approach, we demonstrate that the conserved residues in the putative cyclin-binding motif are important for protein expression, protein half-life, and optimal phosphorylation of SAMHD1 at Thr592. Furthermore, we observed that SAMHD1 mutants of the cyclin-binding motif mislocalized to a nuclear compartment and had reduced ability to interact with cyclin A-CDK complexes and to form the tetramer. These findings help define the mechanisms by which SAMHD1 is phosphorylated and suggest the contribution of cyclin binding to SAMHD1 expression and stability in dividing cells.
AB - SAMHD1 (sterile α motif and HD domain-containing protein 1) is a mammalian protein that regulates intracellular dNTP levels through its hydrolysis of dNTPs. SAMHD1 functions as an important retroviral restriction factor through a mechanism relying on its dNTPase activity. We and others have reported that human SAMHD1 interacts with the cell cycle regulatory proteins cyclin A, CDK1, and CDK2, which mediates phosphorylation of SAMHD1 at threonine 592, a post-translational modification that has been implicated in abrogating SAMHD1 restriction function and ability to form stable tetramers. Utilizing co-immunoprecipitation and colocalization approaches, we show that endogenous SAMHD1 is able to interact with the cyclin A-CDK1-CDK2 complex in monocytic THP-1 cells and primary monocyte-derived macrophages. Sequence analysis of SAMHD1 identifies a putative cyclin-binding motif found in many cyclin-CDK complex substrates. Using a mutagenesis-based approach, we demonstrate that the conserved residues in the putative cyclin-binding motif are important for protein expression, protein half-life, and optimal phosphorylation of SAMHD1 at Thr592. Furthermore, we observed that SAMHD1 mutants of the cyclin-binding motif mislocalized to a nuclear compartment and had reduced ability to interact with cyclin A-CDK complexes and to form the tetramer. These findings help define the mechanisms by which SAMHD1 is phosphorylated and suggest the contribution of cyclin binding to SAMHD1 expression and stability in dividing cells.
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U2 - 10.1074/jbc.M116.753947
DO - 10.1074/jbc.M116.753947
M3 - Article
C2 - 27815502
AN - SCOPUS:85006288723
VL - 291
SP - 26332
EP - 26342
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 51
ER -