Aromatic residues are required for RNA helicase A mediated transactivation.
RNA helicase A (RHA) is a member of ATPase/helicase and regulates the transcription through recruitment of Pol II and/or by ATP dependent mechanisms. In CREB-dependent transcription, RHA recruits RNA polymerase (Pol) II to the CREB binding protein (CBP) via the minimal transactivation domain (MTAD). This region is well conserved among RHA homologues, whereas it is unique to RHA. The three conserved tryptophan residues in MTAD are critical for transactivation. To understand the importance of tryptophan residues on transactivation, we generated mutants in which tryptophan residues were replaced by other aromatic, bulky hydrophobic or small hydrophobic amino acids. Substitutions of tryptophan with either bulky hydrophobic or small hydrophobic amino acid decreased transcriptional activity, whereas aromatic residue had no effect. Moreover, these mutants with tryptophan to phenylalanine, activated CREB-dependent transcription. These results indicate that aromatic characteristics of tryptophan residues in MTAD are important for CREB-dependent transcription via RHA.
Aratani
Satoko
S
Institute of Medical Science, St. Marianna University School of Medicine, Kawasaki, Kanagawa 216-8512, Japan.
Fujii
Ryouji
R
Fujita
Hidetoshi
H
Fukamizu
Akiyoshi
A
Nakajima
Toshihiro
T
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001324:Autoantigens / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism; D053487:DEAD-box RNA Helicases; D006801:Humans; D008322:Mammals; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins; D010649:Phenylalanine / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D020365:RNA Helicases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014364:Tryptophan / Q000235:genetics / Q000378:metabolism*
D001324:Autoantigens; D017362:Cyclic AMP Response Element-Binding Protein; D009363:Neoplasm Proteins; D010649:Phenylalanine; D014364:Tryptophan; C098487:DHX9 protein, human; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases