title: An evaluation of molecular models of the cytochrome P450 Streptomyces griseolus enzymes P450SU1 and P450SU2.
abstract: P450SU1 and P450SU2 are herbicide-inducible bacterial cytochrome P450 enzymes from Streptomyces griseolus. They have two of the highest sequence indentities to camphor hydroxylase (P450cam from Pseudomonas putida), the cytochrome P450 with the first known crystal structure. We have built several models of these two proteins to investigate the variability in the structures that can occur from using different modeling protocols. We looked at variability due to alignment methods, backbone loop conformations and refinement methods. We have constructed two models for each protein using two alignment algorithms, and then an additional model using an identical alignment but different loop conformations for both buried and surface loops. The alignments used to build the models were created using the Needleman-Wunsch method, adapted for multiple sequences, and a manual method that utilized both a dot-matrix search matrix and the Needleman-Wunsch method. After constructing the initial models, several energy minimization methods were used to explore the variability in the final models caused by the choice of minimization techniques. Features of cytochrome P450cam and the cytochrome P450 superfamily, such as the ferredoxin binding site, the heme binding site and the substrate binding site were used to evaluate the validity of the models. Although the final structures were very similar between the models with different alignments, active-site residues were found to be dependent on the conformations of buried loops and early stages of energy minimization. We show which regions of the active site are the most dependent on the particular methods used, and which parts of the structures seem to be independent of the methods.
authors.affiliation: Molecular Science Research Center, Pacific Northwest Laboratory, Battelle Memorial Institute, Richland, WA 99352.
authors.forename: J A
authors.initials: JA
authors.lastname: Braatz
authors.forename: M B
authors.initials: MB
authors.lastname: Bass
authors.forename: R L
authors.initials: RL
authors.lastname: Ornstein
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D001665:Binding Sites; D019475:Camphor 5-Monooxygenase; D017076:Computer-Aided Design; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry* / Q000235:genetics; D015195:Drug Design; D005069:Evaluation Studies as Topic; D005288:Ferredoxins / Q000737:chemistry; D006418:Heme / Q000737:chemistry; D006899:Mixed Function Oxygenases / Q000737:chemistry / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010105:Oxygenases / Q000737:chemistry* / Q000235:genetics; D011487:Protein Conformation; D016958:Pseudomonas putida / Q000201:enzymology / Q000235:genetics; D016415:Sequence Alignment / Q000379:methods; D017386:Sequence Homology, Amino Acid; D012984:Software; D013302:Streptomyces / Q000201:enzymology / Q000235:genetics; D013816:Thermodynamics
chemical_list: D001426:Bacterial Proteins; D005288:Ferredoxins; D006418:Heme; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D010105:Oxygenases; C086254:P450SU1 protein, Streptomyces griseolus; C086255:P450SU2 protein, Streptomyces griseolus; D019475:Camphor 5-Monooxygenase