Binding of BAZF and Bc16 to STAT6-binding DNA sequences

BAZF, a family member of Bc16, can function as a sequence-specific transcriptional repressor. We determined BAZF-binding DNA sequence. The consensus binding sequence (CBS) of BAZF is almost the same as those of Bc16 previously described. Three nucleotides of T, G and A at position 6, 8, and 9 in the CBS (5' -ATTCCTAGAAAG-3') are important nucleotides for binding of both BAZF and Bc16. Since a part (5' -TTC-CTA-GAA-3') of the CBS resembled the sequence motif (5' -TTC-(N3-4)-GAA-3') bound by STAT factors, BAZF and Bc16 can bind to the CD23b-STAT6-binding sequence (5' -TTC-(N3-4)-GAA-3 '),the immunoglobulin germline Epsilon-STATG-binding sequence (5' -CTTC-CCAA-GAAC-3'), and the IL4-STAT6-binding sequence (5' -TTTC-CTA-GAAAA-3') with weak affinity. However, a mutation of C nucleotide to T nucleotide in the IL4-STAT6-binding sequence (5' -TTTC-CTA-GAAAA-3') strongly increased the binding activity of BAZF and Bc16. These results suggest that BAZF and Bc16 can repress some of STAT-induced transcription by binding to DNA sequences recognized by STAT factors. (C) 2001 academic press.