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Abstract Detail


Plant-Pathogen Interactions

Becker-Ritt, Arlete B [1], Martinelli, Anne H S [2], Mitidieri, Sydnei [3], Feder, Vanessa [4], Wassermann, German E [4], Pasquali, Giancarlo [4], Carlini, Celia R [5].

Antifungal activity of ureases from Glycine max and Canavalia ensiformis seeds and a recombinant Helicobacter pylori urease.

Ureases (EC 3.5.1.5) are nickel-dependent metalloenzymes that catalyze the hydrolysis of urea to ammonia and carbon dioxide. Produced by plants, fungi and bacteria, but not by animals, ureases share significant homology and similar mechanisms of catalysis although differing in quaternary structures. While fungal and plant ureases are homo-oligomeric proteins of 90 kDa subunits, bacterial ureases are multimers of two (e.g. Helicobacter pylori) or three subunit complexes. It has been proposed that in plants these enzymes are involved in nitrogen bioavailability and in protection against pathogens. Herein we demonstrate that soybean (Glycine max) embryo-specific urease, jackbean (Canavalia ensiformis) major urease and a recombinant Helicobacter pylori urease impair growth of selected phytopathogenic fungi at sub-micromolar concentrations. This antifungal property of ureases is not affected by treatment of the proteins with an irreversible inhibitor of the ureolytic activity. Scanning electron microscopy of urease-treated fungi suggests plasmolysis and cell wall injuries. Altogether our data indicate that ureases probably contribute to the plant arsenal of defense compounds against predators and phytopathogens and that urease defense mechanism is independent of ammonia release from urea.


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1 - University of Missouri, Biochemistry, 111 Schweitzer Hall, 3910 Buttonwood Drive # 1101, Columbia, Missouri, 65201 7148, United States
2 - Universidade Federal do Rio Grande do Sul, Biologia Celular e Molecula
3 - BioPlus Desenvolvimento Biotecnologico Ltda, Pesquisa e Desenvolvimento
4 - Universidade Federal do Rio Grande do Sul, Biologia Celular e Molecular
5 - Universidade Federal do Rio Grande do Sul, Biofisica

Keywords:
urease
antifungal activity
defense mechanism.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P15097
Abstract ID:2719


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