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Mol. Cell. Biol., 10 1995, 5811-5819, Vol 15, No. 10
PS Knoepfler and MP Kamps
The vertebrate Hox genes, which represent a subset of all homeobox genes,
encode proteins that regulate anterior-posterior positional identity during
embryogenesis and are cognates of the Drosophila homeodomain proteins
encoded by genes composing the homeotic complex (HOM-C). Recently, we
demonstrated that multiple Hox proteins bind DNA cooperatively with both
Pbx1 and its oncogenic derivative, E2A-Pbx1. Here, we show that the highly
conserved pentapeptide motif F/Y-P-W-M- R/K, which occurs in numerous Hox
proteins and is positioned 8 to 50 amino acids N terminal to the
homeodomain, is essential for cooperative DNA binding with Pbx1 and
E2A-Pbx1. Point mutational analysis demonstrated that the tryptophan and
methionine residues within the core of this motif were critical for
cooperative DNA binding. A peptide containing the wild-type pentapeptide
sequence, but not one in which phenylalanine was substituted for
tryptophan, blocked the ability of Hox proteins to bind cooperatively with
Pbx1 or E2A-Pbx1, suggesting that the pentapeptide itself provides at least
one surface through which Hox proteins bind Pbx1. Furthermore, the same
peptide, but not the mutant peptide, stimulated DNA binding by Pbx1,
suggesting that interaction of Hox proteins with Pbx1 through the
pentapeptide motif raises the DNA-binding ability of Pbx1.
Copyright © 1995, American Society for Microbiology
The pentapeptide motif of Hox proteins is required for cooperative DNA binding with Pbx1, physically contacts Pbx1, and enhances DNA binding by Pbx1
Department of Pathology, School of Medicine, University of California, San Diego, La Jolla 92093, USA.
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