High-resolution crystal structure of an artificial (betaalpha)(8)-barrel protein designed from identical half-barrels

• Published in: Biochemistry (Easton) Vol. 48; no. 6; pp. 1145 - 1147
• Main Authors: Höcker, Birte, Lochner, Adriane, Seitz, Tobias, Claren, Jörg, Sterner, Reinhard
• Format: Journal Article
• Language: English
• Published: United States 17.02.2009
• Subjects: Aminohydrolases - chemistry; Crystallography, X-Ray; Protein Structure, Secondary; Recombinant Proteins - chemistry
• ISSN: 1520-4995
• DOI: 10.1021/bi802125b

Ample evidence suggests that the ubiquitous (betaalpha)(8)-barrel enzyme fold has evolved by the duplication and fusion of an ancestral (betaalpha)(4)-half-barrel. To reconstruct this process in the laboratory with a model protein, we earlier fused two copies of the C-terminal half-barrel HisF-C of imidazole glycerol phosphate synthase (HisF) and stepwise stabilized the resulting HisF-CC construct. We now further increased its stability and solubility by introducing two additional amino acid exchanges, which allowed us to crystallize the resulting artificial (betaalpha)(8)-barrel protein HisF-C***C. The analysis of its X-ray structure at 2.1 A resolution reveals a striking similarity to wild-type HisF, helps us to understand its improved stability, and provides further insights into the evolution of (betaalpha)(8)-barrel proteins.