tailieunhanh - Báo cáo khoa học: Phenol hydroxylase from Acinetobacter radioresistens S13 Isolation and characterization of the regulatory component

This paper reports the isolation and characterization of the regulatory moiety of the multicomponent enzyme phenol hydroxylase fromAcinetobacter radioresistensS13 grown on phenol as the only carbon and energy source. The whole enzyme comprises an oxygenase moiety (PHO), a reductase moiety (PHR) and a regulatory moiety (PHI). PHR contains one FAD and one iron-sulfur cluster, whose function is electron transfer from NADH to the dinuclear iron centre of the oxygenase. | Eur. J. Biochem. 270 1434-1440 2003 FEBS 2003 doi Phenol hydroxylase from Acinetobacterradioresistens S13 Isolation and characterization of the regulatory component Ersilia Griva1. Enrica Pessione1. Sara Divari1 Francesca Valetti1 Maria Cavaletto2 Gian Luiai Rossi3 and Carlo Giunta1 1 Dipartimento di Biologia Animate e dell Uomo Universita di Torino Italy 2Dipartimento di Scienze e Tecnologie Avanzate Universita del Piemonte Orientale Alessandria Italy 3Dipartimento di Biochimica e Biologia Molecolare Universita di Parma Italy This paper reports the isolation and characterization of the regulatory moiety of the multicomponent enzyme phenol hydroxylase from Acinetobacter radioresistens S13 grown on phenol as the only carbon and energy source. The whole enzyme comprises an oxygenase moiety PHO a reductase moiety PHR and a regulatory moiety PHI . PHR contains one FAD and one ironsulfur cluster whose function is electron transfer from NADH to the dinuclear iron centre of the oxygenase. PHI is required for catalysis of the conversion of phenol to catechol in vitro but is not required for PHR activity towards alternative electron acceptors such as cytochrome c and Nitro Blue Tetrazolium. The molecular mass of PHI was determined to be 10 kDa by SDS PAGE kDa by MALDI-TOF spectrometry and 18 kDa by gel-permeation. This finding suggests that the protein in its native state is a homodimer. The isoelectric point is . PHI does not contain any redox cofactor and does not bind ANS a fluorescent probe for hydrophobic sites. The N-terminal sequence is similar to those of the regulatory proteins of phenol hydroxylase from A. calcoaceticus and Pseudomonas CF 600. In the reconstituted system optimal reaction rate was achieved when the stoichiometry of the components was 2 PHR monomers 1 PHI dimer 1 PHO aPc dimer. PHI interacts specifically with PHR promoting the enhancement of FAD fluorescence emission. This signal is diagnostic of a .