title: Structural plasticity of 4-α-helical bundles exemplified by the puzzle-like molecular assembly of the Rop protein.
abstract: The dimeric Repressor of Primer (Rop) protein, a widely used model system for the study of coiled-coil 4-α-helical bundles, is characterized by a remarkable structural plasticity. Loop region mutations lead to a wide range of topologies, folding states, and altered physicochemical properties. A protein-folding study of Rop and several loop variants has identified specific residues and sequences that are linked to the observed structural plasticity. Apart from the native state, native-like and molten-globule states have been identified; these states are sensitive to reducing agents due to the formation of nonnative disulfide bridges. Pro residues in the loop are critical for the establishment of new topologies and molten globule states; their effects, however, can be in part compensated by Gly residues. The extreme plasticity in the assembly of 4-α-helical bundles reflects the capacity of the Rop sequence to combine a specific set of hydrophobic residues into strikingly different hydrophobic cores. These cores include highly hydrated ones that are consistent with the formation of interchain, nonnative disulfide bridges and the establishment of molten globules. Potential applications of this structural plasticity are among others in the engineering of bio-inspired materials.
authors.affiliation: Department of Biology, University of Crete, GR 71409 Heraklion, Crete, Greece;Institute of Molecular Biology and Biotechnology, Foundation of Research and Technology, GR 70013 Heraklion, Crete, Greece; and.
authors.forename: Maria
authors.initials: M
authors.lastname: Amprazi
authors.affiliation: Institute of Molecular Biology and Biotechnology, Foundation of Research and Technology, GR 70013 Heraklion, Crete, Greece; and.
authors.forename: Dina
authors.initials: D
authors.lastname: Kotsifaki
authors.affiliation: Institute of Molecular Biology and Biotechnology, Foundation of Research and Technology, GR 70013 Heraklion, Crete, Greece; and.
authors.forename: Mary
authors.initials: M
authors.lastname: Providaki
authors.affiliation: Institute of Molecular Biology and Biotechnology, Foundation of Research and Technology, GR 70013 Heraklion, Crete, Greece; and.
authors.forename: Evangelia G
authors.initials: EG
authors.lastname: Kapetaniou
authors.affiliation: Department of Biology, University of Crete, GR 71409 Heraklion, Crete, Greece;
authors.forename: Georgios
authors.initials: G
authors.lastname: Fellas
authors.affiliation: Department of Biology, University of Crete, GR 71409 Heraklion, Crete, Greece;
authors.forename: Ioannis
authors.initials: I
authors.lastname: Kyriazidis
authors.affiliation: Synchrotron SOLEIL, 91192 Gif-sur-Yvette, France.
authors.forename: Javier
authors.initials: J
authors.lastname: Pérez
authors.affiliation: Department of Biology, University of Crete, GR 71409 Heraklion, Crete, Greece;Institute of Molecular Biology and Biotechnology, Foundation of Research and Technology, GR 70013 Heraklion, Crete, Greece; and kokkinid@imbb.forth.gr.
authors.forename: Michael
authors.initials: M
authors.lastname: Kokkinidis
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D017510:Protein Folding; D017433:Protein Structure, Secondary; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D016601:RNA-Binding Proteins; C054243:Rop protein, ColE1 plasmid
keywords: core packing; dimensionless Kratky plot; disulfide bonds; recurrent tertiary motifs