title: Spontaneous self-assembly of engineered armadillo repeat protein fragments into a folded structure.
abstract: Repeat proteins are built of modules, each of which constitutes a structural motif. We have investigated whether fragments of a designed consensus armadillo repeat protein (ArmRP) recognize each other. We examined a split ArmRP consisting of an N-capping repeat (denoted Y), three internal repeats (M), and a C-capping repeat (A). We demonstrate that the C-terminal MA fragment adopts a fold similar to the corresponding part of the entire protein. In contrast, the N-terminal YM2 fragment constitutes a molten globule. The two fragments form a 1:1 YM2:MA complex with a nanomolar dissociation constant essentially identical to the crystal structure of the continuous YM3A protein. Molecular dynamics simulations show that the complex is structurally stable over a 1 μs timescale and reveal the importance of hydrophobic contacts across the interface. We propose that the existence of a stable complex recapitulates possible intermediates in the early evolution of these repeat proteins.
authors.affiliation: Department of Chemistry, University of Zürich, 8057 Zürich, Switzerland.
authors.forename: Randall P
authors.initials: RP
authors.lastname: Watson
authors.affiliation: Department of Chemistry, University of Zürich, 8057 Zürich, Switzerland.
authors.forename: Martin T
authors.initials: MT
authors.lastname: Christen
authors.affiliation: Department of Chemistry, University of Zürich, 8057 Zürich, Switzerland; Department of Biochemistry, University of Zürich, 8057 Zürich, Switzerland.
authors.forename: Christina
authors.initials: C
authors.lastname: Ewald
authors.affiliation: Department of Chemistry, University of Zürich, 8057 Zürich, Switzerland.
authors.forename: Fabian
authors.initials: F
authors.lastname: Bumbak
authors.affiliation: Department of Biochemistry, University of Zürich, 8057 Zürich, Switzerland.
authors.forename: Christian
authors.initials: C
authors.lastname: Reichen
authors.affiliation: Department of Biochemistry, University of Zürich, 8057 Zürich, Switzerland.
authors.forename: Maja
authors.initials: M
authors.lastname: Mihajlovic
authors.affiliation: Institute of Biophysical Chemistry, Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt am Main, 60438 Frankfurt am Main, Germany.
authors.forename: Elena
authors.initials: E
authors.lastname: Schmidt
authors.affiliation: Institute of Biophysical Chemistry, Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt am Main, 60438 Frankfurt am Main, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Güntert
authors.affiliation: Department of Biochemistry, University of Zürich, 8057 Zürich, Switzerland.
authors.forename: Amedeo
authors.initials: A
authors.lastname: Caflisch
authors.affiliation: Department of Biochemistry, University of Zürich, 8057 Zürich, Switzerland. Electronic address: plueckthun@bioc.uzh.ch.
authors.forename: Andreas
authors.initials: A
authors.lastname: Plückthun
authors.affiliation: Department of Chemistry, University of Zürich, 8057 Zürich, Switzerland. Electronic address: oliver.zerbe@chem.uzh.ch.
authors.forename: Oliver
authors.initials: O
authors.lastname: Zerbe
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D051186:Armadillo Domain Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D015202:Protein Engineering; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D020449:Repetitive Sequences, Amino Acid / Q000235:genetics
chemical_list: D051186:Armadillo Domain Proteins; D010446:Peptide Fragments