tailieunhanh - Báo cáo khoa học: Outer sphere mutagenesis of Lactobacillus plantarum manganese catalase disrupts the cluster core

X-ray crystallography of the nonheme manganese catalase fromLactobacillus plantarum(LPC) [Barynin, ., Whit-taker, ., Antonyuk, ., Lamzin, ., Harrison, ., Artymiuk, . & Whittaker, . (2001)Structure9, 725–738] has revealed the structure of the dimanganese redox cluster together with its protein environment. The oxidized [Mn(III)Mn(III)] cluster is bridged by two solvent molecules (oxo and hydroxo, respectively) together with a l1,3bridging glutamate carboxylate and is embedded in a web of hydrogen bonds involving an outer sphere tyrosine residue (Tyr42). . | Eur. J. Biochem. 270 1102-1116 2003 FEBS 2003 doi Outer sphere mutagenesis of Lactobacillus plantarum manganese catalase disrupts the cluster core Mechanistic implications Mei M. Whittaker1 Vladimir V. Barynin2 3 Takao Igarashi1 and James W. Whittaker1 1 Department of Environmental and Biomolecular Systems OGI School of Science and Engineering at OHSU Oregon 2The Krebs Institute Department of Molecular Biology and Biotechnology University of Sheffield Sheffield The Institute of Crystallography Russian Academy of Sciences Moscow Russia X-ray crystallography of the nonheme manganese catalase from Lactobacillus plantarum LPC Barynin . Whittaker . Antonyuk . Lamzin . Harrison . Artymiuk . Whittaker . 2001 Structure 9 725-738 has revealed the structure of the dimanganese redox cluster together with its protein environment. The oxidized Mn III Mn III cluster is bridged by two solvent molecules oxo and hydroxo respectively together with a l1 3 bridging glutamate carboxylate and is embedded in a web of hydrogen bonds involving an outer sphere tyrosine residue Tyr42 . A novel homologous expression system has been developed for production of active recombinant LPC and Tyr42 has been replaced by phenylalanine using site-directed mutagenesis. Spectroscopic and structural studies indicate that disruption of the hydrogen-bonded web significantly perturbs the active site in Y42F LPC breaking one of the solvent bridges and generating an open form of the dimanganese cluster. Two of the metal ligands adopt alternate conformations in the crystal structure both conformers having a broken solvent bridge in the dimanganese core. The oxidized Y42F LPC exhibits strong optical absorption characteristic of high spin Mn III in low symmetry and lower coordination number. MCD and EPR measurements provide complementary information defining a ferromagnetically coupled electronic ground state for a cluster containing a single solvent bridge in