Previous Article | Next Article ![]()
Mol. Cell. Biol., 03 1995, 1489-1498, Vol 15, No. 3
H Nakagama, G Heinrich, J Pelletier and DE Housman
The Wilms' tumor suppressor gene, WT1, encodes a zinc finger polypeptide
which plays a key role regulating cell growth and differentiation in the
urogenital system. Using the whole-genome PCR approach, we searched murine
genomic DNA for high-affinity WT1 binding sites and identified a 10-bp
motif 5'GCGTGGGAGT3' which we term WTE). The WTE motif is similar to the
consensus binding sequence 5'GCG(G/T)GGGCG3' recognized by EGR-1 and is
also suggested to function as a binding site for WT1, setting up a
competitive regulatory loop. To evaluate the underlying biochemical basis
for such competition, we compared the binding affinities of WT1 and EGR1
for both sequences. WT1 shows a 20- to 30-fold-higher affinity for the WTE
sequence compared with that of the EGR-1 binding motif. Mutational analysis
of the WTE motif revealed a significant contribution to binding affinity by
the adenine nucleotide at the eighth position (5'GCGTGGGAGT3') as well as
by the 3'-most thymine (5'GCGTGGGAGT3'), whereas mutations in either
flanking nucleotides or other nucleotides in the core sequence did not
significantly affect the specific binding affinity. Mutations within WT1
zinc fingers II to IV abolished the sequence-specific binding of WT1 to
WTE, whereas alterations within the first WT1 zinc finger reduced the
binding affinity approximately 10-fold but did not abolish sequence
recognition. We have thus identified a WT1 target, which, although similar
in sequence to the EGR-1 motif, shows a 20- to 30-fold- higher affinity for
WT1. These results suggest that physiological action of WT1 is mediated by
binding sites of significantly higher affinity than the 9-bp EGR-1 binding
motif. The role of the thymine base in contributing to binding affinity is
discussed in the context of recent structural analysis.
Copyright © 1995, American Society for Microbiology
Sequence and structural requirements for high-affinity DNA binding by the WT1 gene product
Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139.
This article has been cited by other articles:
| J. Bacteriol. | J. Virol. | Eukaryot. Cell |
|---|
| Microbiol. Mol. Biol. Rev. | Clin. Vaccine Immunol. | All ASM Journals |
|---|