Cleavage and proteasome-mediated degradation of the basal transcription factor TFIIA.
The transcription factor TFIIA is encoded by two genes, TFIIAalphabeta and TFIIAgamma. In higher eukaryotes, the TFIIAalphabeta is translated as a precursor and undergoes proteolytic cleavage; the regulation and biological implications of the cleavage have remained elusive. We determined by Edman degradation that the TFIIAbeta subunit starts at Asp 278. We found that a cleavage recognition site (CRS), a string of amino acids QVDG at positions -6 to -3 from Asp 278, is essential for cleavage. Mutations in the CRS that prevent cleavage significantly prolong the half-life of TFIIA. Consistently, the cleaved TFIIA is a substrate for the ubiquitin pathway and proteasome-mediated degradation. We show that mutations in the putative phosphorylation sites of TFIIAbeta greatly affect degradation of the beta-subunit. We propose that cleavage and subsequent degradation fine-tune the amount of TFIIA in the cell and consequently the level of transcription.
Høiby
Torill
T
NCMLS, Department of Molecular Biology, HB Nijmegen, The Netherlands.
Mitsiou
Dimitra J
DJ
Zhou
Huiqing
H
Erdjument-Bromage
Hediye
H
Tempst
Paul
P
Stunnenberg
Hendrik G
HG
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002522:Chlorocebus aethiops; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D016415:Sequence Alignment; D013379:Substrate Specificity; D035561:Transcription Factor TFIIA / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism
C119951:GTF2A1L protein, human; D035561:Transcription Factor TFIIA; D014157:Transcription Factors; D046988:Proteasome Endopeptidase Complex