Dimer-to-tetramer assembly of Lac repressor involves a leucine heptad repeat.
The C-terminus of Lac repressor is responsible for the formation of repressor tetramers from active dimers. If properly grafted, the C-terminus of Lac repressor (amino acids 331 to 360) converts Gal repressor dimers into tetramers. Amino acids 342 to 356 of Lac repressor contain a 4-3 hydrophobic repeat of four leucines and one valine. Systematic amino acid replacements of all residues in this region show that the protein-protein interaction between repressor dimers depends mainly on the hydrophobic residues of the 4-3 repeat, which is constitutive for coiled coils. Thus the tetramerization site of Lac repressor resembles the leucine zipper motif found in a family of eukaryotic transcription factors.
Alberti
S
S
Institut für Genetik der Universität zu Köln, FRG.
Oehler
S
S
von Wilcken-Bergmann
B
B
Krämer
H
H
Müller-Hill
B
B
D000595:Amino Acid Sequence; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005813:Genes, Synthetic; D006801:Humans; D007231:Infant, Newborn; D007930:Leucine; D016350:Leucine Zippers / Q000502:physiology; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D012097:Repressor Proteins / Q000737:chemistry* / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid
D029968:Escherichia coli Proteins; C050993:Galactose repressor proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D007930:Leucine