title: A conserved patch of hydrophobic amino acids modulates Myb activity by mediating protein-protein interactions.
abstract: The transcription factor c-Myb plays a key role in the control of proliferation and differentiation in hematopoietic progenitor cells and has been implicated in the development of leukemia and certain non-hematopoietic tumors. c-Myb activity is highly dependent on the interaction with the coactivator p300 which is mediated by the transactivation domain of c-Myb and the KIX domain of p300. We have previously observed that conservative valine-to-isoleucine amino acid substitutions in a conserved stretch of hydrophobic amino acids have a profound effect on Myb activity. Here, we have explored the function of the hydrophobic region as a mediator of protein-protein interactions. We show that the hydrophobic region facilitates Myb self-interaction and binding of the histone acetyl transferase Tip60, a previously identified Myb interacting protein. We show that these interactions are affected by the valine-to-isoleucine amino acid substitutions and suppress Myb activity by interfering with the interaction of Myb and the KIX domain of p300. Taken together, our work identifies the hydrophobic region in the Myb transactivation domain as a binding site for homo- and heteromeric protein interactions and leads to a picture of the c-Myb transactivation domain as a composite protein binding region that facilitates interdependent protein-protein interactions of Myb with regulatory proteins.
authors.affiliation: Institute for Biochemistry, Westfälische-Wilhelms-Universität Münster, D-48149 Münster, Germany; International NRW Graduate School of Chemistry (GSC-MS), Westfälische-Wilhelms-Universität Münster, D-48149 Münster, Germany.
authors.forename: Sandeep
authors.initials: S
authors.lastname: Dukare
authors.affiliation: Institute for Biochemistry, Westfälische-Wilhelms-Universität Münster, D-48149 Münster, Germany. Electronic address: klempna@uni-muenster.de.
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Klempnauer
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D002460:Cell Line; D002645:Chickens; D017124:Conserved Sequence; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007532:Isoleucine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D054730:Protein Interaction Domains and Motifs / Q000235:genetics / Q000502:physiology*; D020598:Proto-Oncogene Proteins c-myb / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011784:Quail; D017386:Sequence Homology, Amino Acid; D015533:Transcriptional Activation / Q000235:genetics; D014633:Valine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D020598:Proto-Oncogene Proteins c-myb; D007532:Isoleucine; D014633:Valine
keywords: Myb; Protein–protein interaction; Tip60; Transactivation; p300