title: Probing fragment complementation by rigid-body docking: in silico reconstitution of calbindin D9k.
abstract: Fragment complementation is gaining an increasing impact as a nonperturbing method to probe noncovalent interactions within protein supersecondary structures. In this study, the fast Fourier transform rigid-body docking algorithm ZDOCK has been employed for in silico reconstitution of the calcium binding protein calbindin D9k, from its two EF-hands subdomains, namely, EF1 (residues 1-43) and EF2 (residues 44-75). The EF1 fragment has been used both in its wild type and in nine mutant forms, in line with in vitro experiments. Consistent with in vitro data, ZDOCK reconstituted the proper fold of wild-type and mutated calbindin, locating the nativelike structures (i.e., holding a root-mean-square deviation < 1 A with respect to the X-ray structure) among the first 10 top-scored solutions out of 4000. Moreover, the three independent in silico reconstitutions of wild-type calbindin ranked a nativelike structure at the top of the output list, that is, the best scored one. The algorithm has been also successfully challenged in reconstituting the EF2 homodimer from two identical copies of the monomer. Furthermore, quantitative models consisting of linear correlations between thermodynamic data and ZDOCK scores were built, providing a tested tool for very fast in silico predictions of the free energy of association of protein-protein complexes solved at the atomic level and known to not undergo significant conformational changes upon binding.
authors.affiliation: Department of Chemistry and Dulbecco Telethon Institute, University of Modena and Reggio Emilia, via Campi 183, 41100 Modena, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Dell'Orco
authors.forename: Michele
authors.initials: M
authors.lastname: Seeber
authors.forename: Pier Giuseppe
authors.initials: PG
authors.lastname: De Benedetti
authors.forename: Francesca
authors.initials: F
authors.lastname: Fanelli
mesh_terms: D064026:Calbindins; D019295:Computational Biology; D003198:Computer Simulation; D009154:Mutation; D011487:Protein Conformation; D017510:Protein Folding; D021122:Protein Subunits; D064030:S100 Calcium Binding Protein G / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D064026:Calbindins; D021122:Protein Subunits; D064030:S100 Calcium Binding Protein G