A novel target for the Wilms' tumour suppressor protein (WT1) is bound by a unique combination of zinc fingers.
All isoforms of the Wilms' tumour suppressor protein, WT1, contain four consecutive zinc fingers which facilitate DNA binding. The predominant WT1 transcript contains a 9 base pair insertion resulting in an additional three amino acids, lysine-threonine-serine (KTS), between zinc fingers 3 and 4. WT1 zinc fingers 2, 3 and 4 are highly homologous to the zinc fingers of the early growth response gene, EGR1. However, only WT1--KTS is capable of binding an EGR1 consensus site. In contrast, the previously described genomic fragment, +P5 (D1S3309E), is bound by both WT1--KTS and WT1 + KTS. In this study, the region within + P5 to which both WT1 -- KTS and WT1 + KTS bind was defined as 5'-GGAGAGGGAGGATC-3'. EGR1 did not bind + P5. By creating zinc finger deletions, we demonstrate that zinc finger 1, but not zinc finger 4, is critical for + P5 binding; whereas zinc finger 4, but not 1, is necessary for the binding of WT1 target sites within EGR1, PDGF A chain and IGF2 promoters. Thus, zinc finger usage can vary with target and + P5 may represent a novel type of WT1 binding site, the physiological relevance of which must be investigated.
Little
M H
MH
Centre for Molecular and Cellular Biology, University of Queensland, St. Lucia, Brisbane, Australia.
Holmes
G
G
Pell
L
L
Caricasole
A
A
Duarte
A
A
Law
M
M
Ward
A
A
Wainwright
B
B
D001665:Binding Sites; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009711:Nucleotides / Q000235:genetics / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D025721:WT1 Proteins; D016335:Zinc Fingers / Q000235:genetics*
D004268:DNA-Binding Proteins; D009711:Nucleotides; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D025721:WT1 Proteins; D004247:DNA