TAILIEUCHUNG - Báo cáo khoa học: Crystal structure of Klebsiella sp. ASR1 phytase suggests substrate binding to a preformed active site that meets the requirements of a plant rhizosphere enzyme

The extracellular phytase of the plant-associatedKlebsiellasp. ASR1 is a member of the histidine-acid-phosphatase family and acts primarily as a scavenger of phosphate groups locked in the phytic acid molecule. The Klebsiellaenzyme is distinguished from theEscherichia coliphytase AppA by its sequence and phytate degradation pathway. | ễFEBS Journal Crystal structure of Klebsiella sp. ASR1 phytase suggests substrate binding to a preformed active site that meets the requirements of a plant rhizosphere enzyme Kerstin Bòhm1 Thomas Herter2 Jurgen J. Muller1 Rainer Borriss2 and Udo Heinemann1 3 1 Kristallographie Max-Delbruck-Centrum fur Molekulare Medizin Berlin Germany 2 Institut fur Biologie Humboldt-Universitat zu Berlin Germany 3 Institut fur Chemie und Biochemie Freie Universitat Berlin Germany Keywords dephosphorylation phytase plant rhizosphere enzyme preformed substrate binding site protein structure Correspondence U. Heinemann Kristallographie Max-Delbruck-Centrum fcjr Molekulare Medizin Robert-Rossle-Str. 10 13125 Berlin Germany Fax 49 30 9406 2548 Tel 49 30 9406 3420 E-mail heinemann@ Database Structural data have been submitted to the Protein Data Bank under the accession numbers 2WNI native PhyK and 2WU0 PhyK H25A Note These authors contributed equally to this work The extracellular phytase of the plant-associated Klebsiella sp. ASR1 is a member of the histidine-acid-phosphatase family and acts primarily as a scavenger of phosphate groups locked in the phytic acid molecule. The Klebsiella enzyme is distinguished from the Escherichia coli phytase AppA by its sequence and phytate degradation pathway. The crystal structure of the phytase from Klebsiella sp. ASR1 has been determined to A resolution using single-wavelength anomalous-diffraction phasing. Despite low sequence similarity the overall structure of Klebsiella phytase bears similarity to other histidine-acid phosphatases such as E. coli phytase glucose-1-phosphatase and human prostatic-acid phosphatase. The polypeptide chain is organized into an a and an a b domain and the active site is located in a positively charged cleft between the domains. Three sulfate ions bound to the catalytic pocket of an inactive mutant suggest a unique binding mode for its substrate phytate. Even in the absence of substrate the .

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