Activation of c-Jun transcription factor by substitution of a charged residue in its N-terminal domain.
C-Jun is a cellular transcription factor that can control gene expression in response to treatment of cells with phorbol esters, growth factors, and expression of some oncogenes. The ability of c-Jun to catalyze the transcription of certain genes is controlled, in part, by changes in the phosphorylation state of specific amino acids in c-Jun. One of the major sites that is phosphorylated during signal response is Ser73. Here we show that substitution of a negatively charged aspartic acid residue at 73 constitutively increased transcriptional activity of c-Jun. The Asp73 substitution also enhanced its availability to bind to DNA in a whole cell extract without altering its intrinsic DNA binding activity since the intrinsic activity was unaltered for the c-Jun mutant proteins expressed in a bacterial system. The negatively charged Asp substitution may mimic the negative charge of a phosphorylated serine at 73. The substitution of an uncharged alanine at 73 resulted in lowered activities. The N-terminal end of c-Jun containing these substitutions was fused to the DNA-binding region of the bovine papilloma virus E2 protein, and was able to confer the same activation properties to the fusion protein at the heterologous E2 DNA-binding site. Ser73 lies in a region of c-Jun previously proposed to bind an uncharacterized inhibitor, perhaps related to a protein of approximately 17.5 kD that coprecipitates along with our c-Jun or the JunE2 fusion products.
Hoeffler
W K
WK
Department of Dermatology, Stanford University Medical School, CA 94305.
Levinson
A D
AD
Bauer
E A
EA
D000595:Amino Acid Sequence; D001224:Aspartic Acid / Q000378:metabolism; D001483:Base Sequence; D002460:Cell Line; D004247:DNA; D004563:Electrochemistry; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D016755:Proto-Oncogene Proteins c-jun / Q000737:chemistry / Q000378:metabolism*; D012694:Serine / Q000378:metabolism; D014158:Transcription, Genetic
D016755:Proto-Oncogene Proteins c-jun; D001224:Aspartic Acid; D012694:Serine; D004247:DNA