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Homeodomain Binding Sites in the Promoter Region of Silk Protein Genes 1
Author(s) -
Hui Chichung,
Suzuki Yoshiaki
Publication year - 1990
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1111/j.1440-169x.1990.00263.x
Subject(s) - silk , homeobox , gene , promoter , genetics , biology , microbiology and biotechnology , transcription factor , gene expression , materials science , composite material
Several 10 bp AT‐rich repeats containing a core sequence TTAATT or its complement, AATTAA, in the distal part of the Bombyx mori fibroin gene promoter are known to bind a group of silk gland factors and to be required for a maximal level of transcription in a posterior silk gland extract. These repeats are similar to a consensus sequence (TCAATTAAAT) of the binding sites deduced for a group of Drosophila homeodomain proteins. By DNasel footprinting assay, two of these proteins, ZEN ( zerknüllt ) and EVE ( even‐skipped ), were shown to bind these sites with high affinity. The “TTAATT” core sequence was found to be important for ZEN and EVE binding by an electrophoretic mobility shift assay. Though these homeodomain proteins apparently recognize the same AT‐rich consensus sequence, we have identified a mutant sequence that enhances ZEN but not EVE binding. Alteration of sequence flanking the repeats was also found to affect the binding of these proteins. The binding of EVE and ZEN was shown to be facilitated by multiple repeats in the binding sites. Similar AT‐rich repeats can be found in the promoter region of other silk protein genes and, as shown here, two regions in the sericin‐1 gene promoter also bind these homeodomain proteins. The interaction of some homeodomain proteins and these homeodomain binding sites might be important for the developmental regulation of a group of silk protein genes.