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Mol. Cell. Biol., Jan 1995, 129-140, Vol 15, No. 1
R Harada, G Berube, OJ Tamplin, C Denis-Larose and A Nepveu
The Drosophila Cut and mammalian Cut-like proteins contain, in addition to
the homeodomain, three other DNA-binding regions called Cut repeats.
Cut-like proteins, therefore, belong to a distinct class of homeodomain
proteins with multiple DNA-binding domains. In this study, we assessed the
DNA-binding specificity of the human Cut repeats by performing PCR-
mediated random oligonucleotide selection with glutathione S- transferase
fusion proteins. Cut repeat 1, Cut repeat 3, and Cut repeat 3 plus the
homeodomain selected related yet distinct sequences. Therefore, sequences
selected by one of the fusion proteins were often, but not always,
recognized by the other proteins. Consensus binding sites were derived for
each fusion protein. In each case, however, some selected sequences
diverged from the consensus but were confirmed to be high-affinity
recognition sites by electrophoretic mobility shift assay. We conclude that
Cut DNA-binding domains have broad, overlapping DNA-binding specificities.
Determination of dissociation constants indicated that in addition to the
core consensus, flanking sequences have a moderate but significant effect
on sequence recognition. Evidence from electrophoretic mobility shift
assay, DNase footprinting, and dissociation constant analyses strongly
suggested that glutathione S-transferase/Cut fusion proteins bind to DNA as
dimers. The implications of these findings are discussed in relation to the
DNA- binding capabilities of Cut repeats. In contrast to other studies, we
found that the human Cut-like protein does not preferably bind to a site
that includes an ATTA homeodomain-binding motif. Here we demonstrate that
the native human Cut-like protein recognizes more efficiently a site
containing an ATCGAT core consensus flanked with G/C- rich sequences.
Copyright © 1995, American Society for Microbiology
DNA-binding specificity of the cut repeats from the human cut-like protein
Molecular Oncology Group, McGill University, Royal Victoria Hospital, Montreal, Quebec, Canada.
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