The 5'-AT-rich half-site of Maf recognition element: a functional target for bZIP transcription factor Maf

Nucleic Acids Res. 2005 Jun 21;33(11):3465-78. doi: 10.1093/nar/gki653. Print 2005.

Abstract

The Maf family of proteins are a subgroup of basic region-leucine zipper (bZIP) transcription factors, which recognize a long palindromic DNA sequence [TGCTGAC(G)TCAGCA] known as the Maf recognition element (MARE). Interestingly, the functional target enhancer sequences present in the alphaA-crystallin gene contain a well-conserved half-site of MARE rather than the entire palindromic sequence. To resolve how Maf proteins bind to target sequences containing only MARE half-sites, we examined their binding activities using electrophoretic gel mobility shift assays as well as in vitro and in vivo reporter assays. Our results indicate that the 5'-flanking region of the MARE half-site is required for Maf proteins to bind both in vitro and in vivo. The critical 5'-flanking sequences for c-Maf were determined by a selection and amplification binding assay and show a preference for AT-rich nucleotides. Furthermore, sequence analysis of the regulatory regions of several target genes also suggests that AT-rich sequences are important. We conclude that Maf can bind to at least two types of target sequences, the classical MARE (palindrome type) and a 5'-AT-rich MARE half-site (half-site type). Our results provide important new insights into the DNA binding and site selection by bZIP transcription factors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 5' Flanking Region*
  • AT Rich Sequence
  • Animals
  • Base Sequence
  • Binding Sites
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / metabolism*
  • Maf Transcription Factors
  • Molecular Sequence Data
  • Protein Structure, Secondary
  • Proto-Oncogene Proteins / chemistry
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-maf
  • Response Elements*
  • Transcription Factors / chemistry
  • Transcription Factors / metabolism*
  • Xenopus laevis

Substances

  • DNA-Binding Proteins
  • L-MAF protein, Gallus gallus
  • Maf Transcription Factors
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-maf
  • Transcription Factors