A novel domain within the DEAD-box protein DP103 is essential for transcriptional repression and helicase activity.
Members of the DEAD-box family of helicases, distinguished by a core characteristic sequence of Asp-Glu-Ala-Asp, are expressed in a wide range of prokaryotes and eukaryotes and exhibit diverse cellular functions, including DNA transcription, recombination and repair, RNA processing, translation, and posttranslational regulation. Although ubiquitous, the function of most DEAD-box proteins is unknown. We and others have recently cloned DP103, which harbors conserved DEAD-box, helicase, and ATPase domains in its N terminus. DP103 (also termed Gemin3 and DDX20) interacts with SF-1, SMN, EBNA2, and EBNA3C in mammalian cells. Here we demonstrate that a discrete domain within the nonconserved C-terminal region of DP103 directly interacts with SF-1. This domain exhibits an autonomous repression function and is necessary and sufficient for repressing the transcriptional activity of SF-1. Furthermore, intact DP103 exhibits helicase activity. Importantly, the C-terminal domain is obligatory but not sufficient for this unwinding activity of DP103. Together, our results support a novel paradigm for transcriptional repression and demonstrate the bifunctional role of the C-terminal domain of DP103.
Yan
Xiaomei
X
Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Mouillet
Jean-François
JF
Ou
Qinglin
Q
Sadovsky
Yoel
Y
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D055541:DEAD Box Protein 20; D053487:DEAD-box RNA Helicases; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D051717:Fushi Tarazu Transcription Factors; D018398:Homeodomain Proteins; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D020365:RNA Helicases / Q000235:genetics / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D054339:Steroidogenic Factor 1; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D051717:Fushi Tarazu Transcription Factors; D018398:Homeodomain Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D011994:Recombinant Proteins; D012097:Repressor Proteins; D054339:Steroidogenic Factor 1; D014157:Transcription Factors; D055541:DEAD Box Protein 20; C485624:Ddx20 protein, mouse; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases