Computer-aided modeling of pentachlorophenol 4-monooxygenase and site-directed mutagenesis of its active site.
Homology modeling was used to construct a model of the three-dimensional structure of pentachlorophenol 4-monooxygenase (PcpB). A PSI-BLAST homology search was initially performed to identify the 3D structure of proteins homologous with PcpB. The feasibility of modeled structures of PcpB was evaluated by Verify3D, which calculated structural compatibility scores based on 3D-1D profiles. The predicted structure of PcpB had an acceptable 3D-1D self-compatibility score, beyond the incorrect fold score threshold. A PcpB-pentachlorophenol (PCP) complex was then constructed utilizing the modeled PcpB structure. After energy minimization of the complex, and successive minimizations of the system that consisted of the complex and the water layer surrounding the complex, the molecular dynamics of the system were simulated. The active-site residues of PcpB were identified on the basis of the modeled structure, and PcpB mutants were then designed to change the active site residues, expressed, and purified by affinity chromatography. The mutant activity was compared with that of the wild-type to investigate the validity of the modeled structure. The experimental results suggested that Phe85, Tyr216, and Arg235 were relevant to enzyme activity, and that Tyr397 and Phe87 were important for stabilization of the structure of PcpB.
Laboratory for Remediation Research, Environmental Plant Research Group, Plant Science Center, RIKEN Institute, yokohama, Konagawa, Japan. nakamura.takashi@nies.go.jp
Takashi
T
Nakamura
Takayuki
T
Motoyama
Takatsugu
T
Hirokawa
Shuichi
S
Hirono
Isamu
I
Yamaguchi
D001665:Binding Sites / Q000235:genetics; D003198:Computer Simulation; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D006899:Mixed Function Oxygenases / Q000737:chemistry* / Q000235:genetics* / Q000302:isolation & purification; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D020133:Reverse Transcriptase Polymerase Chain Reaction
D007527:Isoenzymes; D006899:Mixed Function Oxygenases; C069781:pentachlorophenol monooxygenase