title: NMR studies of interactions between Bax and BH3 domain-containing peptides in the absence and presence of CHAPS.
abstract: Activation and oligomerisation of Bax, a key pro-apoptotic Bcl-2 family protein, are key steps in the mitochondrial pathway to apoptosis. The signals for apoptosis are conveyed by the distantly related BH3-only proteins, which use their short BH3 domain, an amphipathic α-helix, to interact with other Bcl-2 family members. Here we report an NMR study of interactions between BaxΔC and BH3 domain-containing peptides in the absence and presence of CHAPS, a zwitterionic detergent. We find for the first time that CHAPS interacts weakly with BaxΔC (fast exchange on the NMR chemical shift timescale), at concentrations below micelle formation and with an estimated Kd in the tens of mM. Direct and relatively strong-interactions (slow exchange on the NMR chemical shift timescale) were also observed for BaxΔC with BaxBH3 (estimated Kd of circa 150μM) or BimBH3 in the absence of CHAPS. The interaction with either peptide alone induced widespread chemical shift perturbations to BaxΔC in solution which implies that BaxΔC might have undergone significant conformation change upon binding the BH3 peptide. However, BaxΔC remained monomeric upon binding either CHAPS or a BH3 peptide alone, but the presence of both provoked it to form a dimer.
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, The University of Melbourne, Victoria 3010, Australia; Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia. Electronic address: shyao@unimelb.edu.au.
authors.forename: Shenggen
authors.initials: S
authors.lastname: Yao
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, The University of Melbourne, Victoria 3010, Australia.
authors.forename: Dana
authors.initials: D
authors.lastname: Westphal
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, The University of Melbourne, Victoria 3010, Australia.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Babon
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia.
authors.forename: Geoff V
authors.initials: GV
authors.lastname: Thompson
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, The University of Melbourne, Victoria 3010, Australia.
authors.forename: Adeline Y
authors.initials: AY
authors.lastname: Robin
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, The University of Melbourne, Victoria 3010, Australia.
authors.forename: Jerry M
authors.initials: JM
authors.lastname: Adams
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, The University of Melbourne, Victoria 3010, Australia.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Colman
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, The University of Melbourne, Victoria 3010, Australia. Electronic address: czabotar@wehi.edu.au.
authors.forename: Peter E
authors.initials: PE
authors.lastname: Czabotar
mesh_terms: D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000737:chemistry / Q000378:metabolism*; D000072224:Bcl-2-Like Protein 11; D002793:Cholic Acids / Q000378:metabolism*; D003902:Detergents / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism*; D011487:Protein Conformation; D060066:Protein Interaction Maps; D055503:Protein Multimerization; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000378:metabolism*; D051028:bcl-2-Associated X Protein / Q000737:chemistry / Q000378:metabolism*
chemical_list: D051017:Apoptosis Regulatory Proteins; C000606775:BCL2L11 protein, human; C474007:Bax protein (53-86); D000072224:Bcl-2-Like Protein 11; D002793:Cholic Acids; D003902:Detergents; D008565:Membrane Proteins; D010446:Peptide Fragments; D011518:Proto-Oncogene Proteins; D051028:bcl-2-Associated X Protein; C028213:3-((3-cholamidopropyl)dimethylammonium)-1-propanesulfonate
keywords: Apoptosis; BH3 domains; Bax; CHAPS; Dimerization; NMR