title: Functional redundancy between the transcriptional activation domains of E2A is mediated by binding to the KIX domain of CBP/p300.
abstract: The E-protein transcription factors play essential roles in lymphopoiesis, with E12 and E47 (hereafter called E2A) being particularly important in B cell specification and maturation. The E2A gene is also involved in a chromosomal translocation that results in the leukemogenic oncoprotein E2A-PBX1. The two activation domains of E2A, AD1 and AD2, display redundant, independent, and cooperative functions in a cell-dependent manner. AD1 of E2A functions by binding the transcriptional co-activator CBP/p300; this interaction is required in oncogenesis and occurs between the conserved ϕ-x-x-ϕ-ϕ motif in AD1 and the KIX domain of CBP/p300. However, co-activator recruitment by AD2 has not been characterized. Here, we demonstrate that the first of two conserved ϕ-x-x-ϕ-ϕ motifs within AD2 of E2A interacts at the same binding site on KIX as AD1. Mutagenesis uncovered a correspondence between the KIX-binding affinity of AD2 and transcriptional activation. Although AD2 is dispensable for oncogenesis, experimentally increasing the affinity of AD2 for KIX uncovered a latent potential to mediate immortalization of primary hematopoietic progenitors by E2A-PBX1. Our findings suggest that redundancy between the two E2A activation domains with respect to transcriptional activation and oncogenic function is mediated by binding to the same surface of the KIX domain of CBP/p300.
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Denis
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada.
authors.forename: David N
authors.initials: DN
authors.lastname: Langelaan
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada.
authors.forename: Alyssa C
authors.initials: AC
authors.lastname: Kirlin
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada.
authors.forename: Seth
authors.initials: S
authors.lastname: Chitayat
authors.affiliation: Protein Function Discovery Group, Queen's University, Kingston, Ontario, K7L 3N6, Canada.
authors.forename: Kim
authors.initials: K
authors.lastname: Munro
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada.
authors.forename: Holly L
authors.initials: HL
authors.lastname: Spencer
authors.affiliation: Protein Function Discovery Group, Queen's University, Kingston, Ontario, K7L 3N6, Canada Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, K7L 3N6, Canada Division of Cancer Biology and Genetics, Cancer Research Institute, Queen's University, Kingston, Ontario, K7L 3N6, Canada steven.smith@queensu.ca.
authors.forename: David P
authors.initials: DP
authors.lastname: LeBrun
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada Protein Function Discovery Group, Queen's University, Kingston, Ontario, K7L 3N6, Canada steven.smith@queensu.ca.
authors.forename: Steven P
authors.initials: SP
authors.lastname: Smith
mesh_terms: D001665:Binding Sites; D001854:Bone Marrow Cells / Q000378:metabolism; D008958:Models, Molecular; D054730:Protein Interaction Domains and Motifs; D017434:Protein Structure, Tertiary; D058127:Transcription Factor 3 / Q000737:chemistry* / Q000378:metabolism; D015533:Transcriptional Activation; D050880:p300-CBP Transcription Factors / Q000737:chemistry* / Q000378:metabolism
chemical_list: D058127:Transcription Factor 3; D050880:p300-CBP Transcription Factors