RP58 associates with condensed chromatin and mediates a sequence-specific transcriptional repression.
An approximately 120-amino acid domain present generally at the NH2 termini, termed the POZ domain, is highly conserved in various proteins with zinc finger DNA binding motifs. We have isolated a novel protein sharing homology with the POZ domain of a number of zinc finger proteins, including the human BCL-6 protein. By using a binding site selection technique (CAST), a high affinity binding site of the protein was determined to be (A/C)ACATCTG(G/T)(A/C), containing the E box core sequence motif. The protein was shown to repress transcription from a promoter linked to its target sequences and was hence named RP58 (Repressor Protein with a predicted molecular mass of 58 kDa). Immunogold electron microscopic study revealed that almost all RP58 is localized in condensed chromatin regions. These observations demonstrate for the first time that a protein mediating a sequence-specific transcriptional repression associates with highly condensed chromatin. We suggest that RP58 may be involved in a molecular link between sequence-specific transcriptional repression and the organization of chromosomes in the nucleus.
Department of Immunology, Division of Genetic Resources, National Institute of Infectious Diseases, Tokyo, Japan.
K
K
Aoki
G
G
Meng
K
K
Suzuki
T
T
Takashi
Y
Y
Kameoka
K
K
Nakahara
R
R
Ishida
M
M
Kasai
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D019556:COS Cells; D002843:Chromatin / Q000378:metabolism*; D003001:Cloning, Molecular; D016384:Consensus Sequence; D004247:DNA; D006801:Humans; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D002843:Chromatin; D012097:Repressor Proteins; D014157:Transcription Factors; C115048:ZBTB18 protein, human; D004247:DNA