Contribution of Individual Amino Acids to the RNA Binding Activity of the Wilms’ Tumor Suppressor Protein WT1

• Published in: Biochemistry (Easton) 2009-01, Vol.48 (1), p.148-155
• Main Authors: Weiss, Tristen C, Romaniuk, Paul J
• Format: Article
• Language: English
• Subjects: Amino Acids - chemistry; Aptamers, Nucleotide - chemistry; DNA - chemistry; Mutation; Nucleic Acid Conformation; Protein Binding; RNA - chemistry; WT1 Proteins - chemistry; WT1 Proteins - genetics; Zinc Fingers
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi801586a

In addition to binding to DNA, the zinc finger protein WT1 can also bind specifically to RNA. To determine the role of individual zinc fingers of the protein in this RNA binding activity, deletion and substitution mutants of the WT1 zinc finger domain were constructed. The effects of the various mutations on the binding of WT1 to the RNA aptamers RNA22 and RNA38 were determined using a quantitative equilibrium binding assay. The results indicate that zinc fingers 2 and 3 of WT1 are essential for the binding of the protein to the RNA aptamers. For both of these fingers, the arginine residue immediately preceding the α-helix makes a significant contribution to RNA binding. For zinc finger 2, a second arginine residue within the α-helix is also critical for RNA binding, while several α-helical residues in zinc finger 3 contribute to the overall affinity of WT1 for RNA. Investigating the effects of the same point mutations on DNA binding indicates that there are similarities and differences in the contributions of zinc fingers 2 and 3 to the DNA and RNA binding activities of WT1.