TY - JOUR
T1 - Phosphorylation of threonine 204 of DEAD-box RNA helicase DDX3 by cyclin B/cdc2 in vitro
AU - Sekiguchi, Takeshi
AU - Kurihara, Yoshiko
AU - Fukumura, Junko
N1 - Funding Information:
This work was supported by a Grant-in-Aid for Scientific Research on Priority Areas (T.S.) from the Japan Ministry of Education, Science, Sport and Culture.
PY - 2007/5/11
Y1 - 2007/5/11
N2 - DDX3 is a DEAD-box RNA helicase involved in human immunodeficiency virus mRNA export and translation. Previously, we reported that DDX3 is required for cyclin A expression. To examine whether DDX3 is regulated at the post-transcriptional level, we determined the phosphorylation sites of hamster DDX3 in vitro. Threonine 204 (Thr204) is a conserved amino acid residue of DDX3 homologues in yeast, frog, hamster, and human that is located within motif Q of DEAD-box RNA helicases. A Thr204 to Glu204 DDX3 mutant protein lost its function, suggesting that phosphorylation at Thr204 affects DDX3 function. Thr204 was phosphorylated by cyclin B/cdc2. Thr323 in motif Ib was also phosphorylated by cyclin B/cdc2 kinase. We propose a novel function of cyclin B/cdc2 kinase in mitosis, which is to cause a loss of DDX3 function to repress cyclin A expression and to decrease ribosome biogenesis and translation during mitosis.
AB - DDX3 is a DEAD-box RNA helicase involved in human immunodeficiency virus mRNA export and translation. Previously, we reported that DDX3 is required for cyclin A expression. To examine whether DDX3 is regulated at the post-transcriptional level, we determined the phosphorylation sites of hamster DDX3 in vitro. Threonine 204 (Thr204) is a conserved amino acid residue of DDX3 homologues in yeast, frog, hamster, and human that is located within motif Q of DEAD-box RNA helicases. A Thr204 to Glu204 DDX3 mutant protein lost its function, suggesting that phosphorylation at Thr204 affects DDX3 function. Thr204 was phosphorylated by cyclin B/cdc2. Thr323 in motif Ib was also phosphorylated by cyclin B/cdc2 kinase. We propose a novel function of cyclin B/cdc2 kinase in mitosis, which is to cause a loss of DDX3 function to repress cyclin A expression and to decrease ribosome biogenesis and translation during mitosis.
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U2 - 10.1016/j.bbrc.2007.03.038
DO - 10.1016/j.bbrc.2007.03.038
M3 - Article
C2 - 17379183
AN - SCOPUS:33947630777
SN - 0006-291X
VL - 356
SP - 668
EP - 673
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 3
ER -
