[Negative repressor THZif-1 of protooncogene c-myc].
A human recombinant cDNA clone that encoded 253 amino acids residues of a zinc-finger protein (THZif-1) was cloned by screening a cDNA library prepared from human promyelocytic leukemia HL60 cells with synthetic oligodeoxynucleotide probes that corresponded to the amino acid sequences of tryptic peptides derived from the DNA-binding protein specific for the nuclease-hypersensitive element (NHE) of the human c-myc gene. The predicted amino acid sequence of THZif-1 included a DNA-binding domain that contained five tandemly repeated zinc finger motifs. The three amino-terminal sets of zinc finger motifs, including the second finger, were found to be responsible for high-affinity interactions with the triple-helical conformation of NHE, as well as for high-affinity binding to the single-pyrimidine-rich strand of NHE in a sequence-specific manner. Cotransfection, trans-activation and in vitro transcription studies using the wild-type form and THZif-1 with a mutated second zinc finger motif demonstrated that the DNA-binding activity specific for H-form DNA of NHE was a prerequisite for the negative regulation of the expression of the c-myc gene.
RIKEN (The Institute of Physical and Chemical Research), Tsukuba Life Science Center.
K
K
Yokoyama
H
H
Tsutsui
A
A
Fujita
D000595:Amino Acid Sequence; D000818:Animals; D004268:DNA-Binding Proteins; D015972:Gene Expression Regulation, Neoplastic; D016147:Genes, Tumor Suppressor; D016259:Genes, myc; D018257:Helix-Loop-Helix Motifs; D006801:Humans; D008969:Molecular Sequence Data; D012097:Repressor Proteins; D016335:Zinc Fingers
D004268:DNA-Binding Proteins; D012097:Repressor Proteins; C102581:THZif-1 protein, human