The class II trans-activator CIITA interacts with the TBP-associated factor TAFII32.
The class II trans- activator (CIITA) is the main transcriptional co-activator for the expression of MHC class II proteins. Its N-terminal 125 amino acids function as an independent transcriptional activation domain. Analyses of the primary amino acid sequence of the activation domain predict the presence of three alpha-helices, each with a high proportion of acidic residues. Using site-directed mutagenesis, we found that two of these predicted alpha-helices are required for full transcriptional activation by CIITA. Moreover, a CIITA protein in which both functional alpha-helices have been deleted displays a dominant negative phenotype. This activation domain of CIITA interacts with the 32 kDa subunit of the general transcription complex TFIID, TAFII32. Decreased transcriptional activation by N-terminal deletions of CIITA is correlated directly with their reduced binding to TAFII32. We conclude that interactions between TAFII32 and CIITA are responsible for activation of class II genes.
Fontes
J D
JD
Howard Hughes Medical Institute, Department of Medicine, University of California at San Francisco, San Francisco, CA 94143-0724, USA.
Jiang
B
B
Peterlin
B M
BM
D000595:Amino Acid Sequence; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D004926:Escherichia coli; D005802:Genes, MHC Class II; D006367:HeLa Cells; D006801:Humans; D015448:Leukemia, B-Cell / Q000276:immunology; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins; D017354:Point Mutation; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D035381:TATA-Binding Protein Associated Factors; D015534:Trans-Activators / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D035362:Transcription Factor TFIID; D019473:Transcription Factors, TFII / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection
C083728:MHC class II transactivator protein; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; C106849:TAF9 protein, human; D035381:TATA-Binding Protein Associated Factors; D015534:Trans-Activators; D035362:Transcription Factor TFIID; D019473:Transcription Factors, TFII