Krüppel-associated boxes are potent transcriptional repression domains.
The Krüppel-associated box (KRAB) is a highly conserved, 75-aa region containing two predicted amphipathic alpha-helices. The KRAB domain is present in the amino-terminal regions of more than one-third of all Krüppel-class Cys2His2 zinc finger proteins and is conserved from yeast to man; however, its function is unknown. Here it is shown that the KRAB domain functions as a DNA binding-dependent transcriptional repressor when fused to a heterologous DNA-binding domain from the yeast GAL4 protein. A 45-aa segment containing one of the predicted KRAB amphipathic helices was necessary and sufficient for repression. Amino acid substitutions in the predicted helix abolished the repression function. These results assign a function, transcriptional repression, to the highly conserved KRAB box and define a minimal repression domain which may aid in identifying mechanisms of repression.
Margolin
J F
JF
Wistar Institute, Philadelphia, PA 19104.
Friedman
J R
JR
Meyer
W K
WK
Vissing
H
H
Thiesen
H J
HJ
Rauscher
F J
FJ
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000096:biosynthesis / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D051741:Kruppel-Like Transcription Factors; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016133:Polymerase Chain Reaction; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism*; D015183:Restriction Mapping; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection; D016335:Zinc Fingers / Q000235:genetics
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C052130:GAL4 protein, S cerevisiae; D051741:Kruppel-Like Transcription Factors; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors