Year: 2006
Type: article
Abstract: The plant R2R3 Myb gene family is one of the largest families of transcription factors described to date.Discrete evolutionary steps have shaped the plant-specific R2R3 Myb gene family from the broadly distributed R1R2R3 Myb genes.After the loss of the R1 repeat during the evolution of the Myb gene family, several conserved residues of the R2R3 MYB domains underwent a series of substitutions.These changes include the insertion of a Leu residue at position 46, the change of a highly conserved Pro to Ala at position 63 and the change of a characteristic Trp residue at position 70 to other large hydrophobic residues.In the studies presented here, I have utilized the MYB domain of the maize P1 protein as a model to investigate how evolutionary changes have shaped the R2R3 Myb gene family.Using a variety of techniques, I have investigated the effects of these changes on the ability of the MYB domain to bind to DNA, the overall conformation of the MYB domain and the ability to activate transcription in vivo.Here, the deletion of Leu46 showed large changes in all of the assays performed, which highlights the importance of this residue in the function of the MYB domain.I also demonstrate that changing the Ala63 and Ile70 back to the conserved Pro and Trp residues, respectively, does not induce changes detectable by the assays used here.In addition, I show that the region surrounding amino acid 15 in the MYB domain and a region C-terminal to the putative activation domain are important for the ability to activate transcription in vivo.Evidence is presented that highlights the regulatory activity of two conserved Cys residues found in the MYB domain that form a disulfide bond under oxidizing conditions.When this disulfide bond is present, the ability of the MYB domain to bind DNA is inhibited.In addition, when the intracellular signaling molecule NO is present, a disulfide bond can also form between these Cys residues.This study demonstrates that NO has the potential to induce the intramolecular disulfide bond formation between the CHAPTER 1
Author: George F. Heine
Institution: The Ohio State University
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2741064962