title: Modulation of allostery by protein intrinsic disorder.
abstract: Allostery is an intrinsic property of many globular proteins and enzymes that is indispensable for cellular regulatory and feedback mechanisms. Recent theoretical and empirical observations indicate that allostery is also manifest in intrinsically disordered proteins, which account for a substantial proportion of the proteome. Many intrinsically disordered proteins are promiscuous binders that interact with multiple partners and frequently function as molecular hubs in protein interaction networks. The adenovirus early region 1A (E1A) oncoprotein is a prime example of a molecular hub intrinsically disordered protein. E1A can induce marked epigenetic reprogramming of the cell within hours after infection, through interactions with a diverse set of partners that include key host regulators such as the general transcriptional coactivator CREB binding protein (CBP), its paralogue p300, and the retinoblastoma protein (pRb; also called RB1). Little is known about the allosteric effects at play in E1A-CBP-pRb interactions, or more generally in hub intrinsically disordered protein interaction networks. Here we used single-molecule fluorescence resonance energy transfer (smFRET) to study coupled binding and folding processes in the ternary E1A system. The low concentrations used in these high-sensitivity experiments proved to be essential for these studies, which are challenging owing to a combination of E1A aggregation propensity and high-affinity binding interactions. Our data revealed that E1A-CBP-pRb interactions have either positive or negative cooperativity, depending on the available E1A interaction sites. This striking cooperativity switch enables fine-tuning of the thermodynamic accessibility of the ternary versus binary E1A complexes, and may permit a context-specific tuning of associated downstream signalling outputs. Such a modulation of allosteric interactions is probably a common mechanism in molecular hub intrinsically disordered protein function.
authors.affiliation: Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
authors.forename: Allan Chris M
authors.initials: AC
authors.lastname: Ferreon
authors.forename: Josephine C
authors.initials: JC
authors.lastname: Ferreon
authors.forename: Peter E
authors.initials: PE
authors.lastname: Wright
authors.forename: Ashok A
authors.initials: AA
authors.lastname: Deniz
mesh_terms: D017500:Adenovirus E1A Proteins / Q000737:chemistry* / Q000378:metabolism*; D000494:Allosteric Regulation; D020816:Amino Acid Motifs; D000818:Animals; D016880:Anisotropy; D050882:CREB-Binding Protein / Q000737:chemistry / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D051379:Mice; D008958:Models, Molecular; D011485:Protein Binding; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D016160:Retinoblastoma Protein / Q000737:chemistry / Q000378:metabolism; D013816:Thermodynamics; D050880:p300-CBP Transcription Factors / Q000737:chemistry
chemical_list: D017500:Adenovirus E1A Proteins; D016160:Retinoblastoma Protein; D050882:CREB-Binding Protein; D050880:p300-CBP Transcription Factors