title: Cooperative Subunit Refolding of a Light-Harvesting Protein through a Self-Chaperone Mechanism.
abstract: The fold of a protein is encoded by its amino acid sequence, but how complex multimeric proteins fold and assemble into functional quaternary structures remains unclear. Here we show that two structurally different phycobiliproteins refold and reassemble in a cooperative manner from their unfolded polypeptide subunits, without biological chaperones. Refolding was confirmed by ultrafast broadband transient absorption and two-dimensional electronic spectroscopy to probe internal chromophores as a marker of quaternary structure. Our results demonstrate a cooperative, self-chaperone refolding mechanism, whereby the β-subunits independently refold, thereby templating the folding of the α-subunits, which then chaperone the assembly of the native complex, quantitatively returning all coherences. Our results indicate that subunit self-chaperoning is a robust mechanism for heteromeric protein folding and assembly that could also be applied in self-assembled synthetic hierarchical systems.
authors.affiliation: School of Chemistry, the Australian Centre for NanoMedicine and the ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, The University of New South Wales, Sydney, 2052, NSW, Australia.|School of Physics, The University of New South Wales, Sydney, 2052, NSW, Australia.
authors.forename: Alistair J
authors.initials: AJ
authors.lastname: Laos
authors.affiliation: Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA.
authors.forename: Jacob C
authors.initials: JC
authors.lastname: Dean
authors.affiliation: Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA.
authors.forename: Zi S D
authors.initials: ZSD
authors.lastname: Toa
authors.affiliation: School of Physics, The University of New South Wales, Sydney, 2052, NSW, Australia.
authors.forename: Krystyna E
authors.initials: KE
authors.lastname: Wilk
authors.affiliation: Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA.
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Scholes
authors.affiliation: School of Physics, The University of New South Wales, Sydney, 2052, NSW, Australia.
authors.forename: Paul M G
authors.initials: PMG
authors.lastname: Curmi
authors.affiliation: School of Chemistry, the Australian Centre for NanoMedicine and the ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, The University of New South Wales, Sydney, 2052, NSW, Australia.
authors.forename: Pall
authors.identifier: 0000-0002-1200-8814
authors.initials: P
authors.lastname: Thordarson
mesh_terms: D006863:Hydrogen-Ion Concentration; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry*; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry*; D058849:Protein Refolding
chemical_list: D045342:Light-Harvesting Protein Complexes; D018832:Molecular Chaperones
keywords: cooperative effects; protein complexes; protein folding; self-assembly; ultrafast spectroscopy