Designed to be stable: Crystal structure of a consensus ankyrin repeat protein

• DOI: 10.1073/pnas.0337680100
• Publication Date: 2003-02-18T20:04:50Z
• Authors: Andreas Kohl; H. Kaspar Binz; Patrik Forrer; Michael T. Stumpp; Andreas Plückthun; Markus G. Grütter
• Keywords: Ankyrin repeat; Ramachandran plot; Ankyrin; Protein design

Ankyrin repeat (AR) proteins mediate innumerable protein-protein interactions in virtually all phyla. This finding suggested the use of AR as designed binding molecules. Based on sequence and structural analyses, we a consensus with fixed framework randomized interacting residues. We generated several combinatorial libraries consisting defined numbers this repeat. Randomly chosen library members are expressed soluble form cytoplasm Escherichia coli constituting up to 30% total cellular protein show high thermodynamic stability. determined crystal structure one those 2.0-A resolution, providing insight into fold. Besides highly complementary hydrophobic repeat-repeat interfaces absence irregularities protein, regular extended hydrogen bond networks beta-turn loop regions noteworthy. Furthermore, residues found turn region Ramachandran plot glycines. Many these features also occur natural proteins, but not rigorous standardized fashion. conclude that domain fold is an intrinsically very stable well-expressed scaffold, able display scaffold represents excellent basis for design novel