title: Modular peptide binding: from a comparison of natural binders to designed armadillo repeat proteins.
abstract: Several binding scaffolds that are not based on immunoglobulins have been designed as alternatives to traditional monoclonal antibodies. Many of them have been developed to bind to folded proteins, yet cellular networks for signaling and protein trafficking often depend on binding to unfolded regions of proteins. This type of binding can thus be well described as a peptide-protein interaction. In this review, we compare different peptide-binding scaffolds, highlighting that armadillo repeat proteins (ArmRP) offer an attractive modular system, as they bind a stretch of extended peptide in a repeat-wise manner. Instead of generating each new binding molecule by an independent selection, preselected repeats - each complementary to a piece of the target peptide - could be designed and assembled on demand into a new protein, which then binds the prescribed complete peptide. Stacked armadillo repeats (ArmR), each typically consisting of 42 amino acids arranged in three α-helices, build an elongated superhelical structure which enables binding of peptides in extended conformation. A consensus-based design approach, complemented with molecular dynamics simulations and rational engineering, resulted in well-expressed monomeric proteins with high stability. Peptide binders were selected and several structures were determined, forming the basis for the future development of modular peptide-binding scaffolds.
authors.affiliation: Department of Biochemistry, University of Zurich, 8057 Zurich, Switzerland.
authors.forename: Christian
authors.initials: C
authors.lastname: Reichen
authors.affiliation: Department of Biochemistry, University of Zurich, 8057 Zurich, Switzerland.
authors.forename: Simon
authors.initials: S
authors.lastname: Hansen
authors.affiliation: Department of Biochemistry, University of Zurich, 8057 Zurich, Switzerland. Electronic address: plueckthun@bioc.uzh.ch.
authors.forename: Andreas
authors.initials: A
authors.lastname: Plückthun
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D006801:Humans; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry*; D011485:Protein Binding; D015202:Protein Engineering; D054730:Protein Interaction Domains and Motifs; D055550:Protein Stability; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry*; D020449:Repetitive Sequences, Amino Acid
chemical_list: D010446:Peptide Fragments; D011506:Proteins
keywords: Libraries; Peptide binding; Protein design; Protein engineering; Protein–peptide interactions; Proteomics; Repeat proteins