The cysteine-rich LIM domains inhibit DNA binding by the associated homeodomain in Isl-1

EMBO J. 1993 Nov;12(11):4243-50.

Abstract

Recently, a new class of homeobox genes has been identified, called LIM-homeobox genes. These genes encode proteins which have two tandemly repeated cysteine motifs, referred to as LIM domains, in addition to a homeodomain. In addition, proteins with only LIM domains have been described but the function of the LIM domain is unknown. We have analysed the function of LIM domains using Isl-1 as a representative LIM-homeodomain protein. Employing protein prepared in bacterial cells, we show that the presence of the LIM domain in Isl-1 inhibits binding of the homeodomain to its DNA target. This in vitro inhibition can be released either by denaturation/renaturation of the protein or by truncation of the LIM domains. A similar inhibition is observed in vivo using reporter constructs. In addition we show that LIM domains in a chimeric protein can inhibit binding of the Ubx homeodomain to its target. The ability of LIM domains to inhibit DNA binding by the homeodomain provides a possible basis for negative regulation of LIM-homeodomain proteins in vivo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Binding Sites
  • Cysteine / genetics*
  • Cysteine / metabolism
  • DNA Mutational Analysis
  • DNA-Binding Proteins / genetics*
  • DNA-Binding Proteins / metabolism
  • Drosophila Proteins*
  • Endopeptidase K
  • Gene Expression Regulation*
  • Genes, Homeobox*
  • Genes, Reporter
  • Homeodomain Proteins*
  • LIM-Homeodomain Proteins
  • Molecular Sequence Data
  • Multigene Family*
  • Nerve Tissue Proteins*
  • Protein Conformation
  • Recombinant Fusion Proteins / metabolism
  • Regulatory Sequences, Nucleic Acid
  • Serine Endopeptidases / metabolism
  • Structure-Activity Relationship
  • Transcription Factors*
  • Transcriptional Activation

Substances

  • DNA-Binding Proteins
  • Drosophila Proteins
  • Homeodomain Proteins
  • LIM-Homeodomain Proteins
  • Nerve Tissue Proteins
  • Recombinant Fusion Proteins
  • Transcription Factors
  • Ubx protein, Drosophila
  • insulin gene enhancer binding protein Isl-1
  • Serine Endopeptidases
  • Endopeptidase K
  • Cysteine