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Novel Bifunctional Inhibitor of Xylanase and Aspartic Protease: Implications for Inhibition of Fungal Growth

By Chandravanu Dash, Absar Ahmad, Devyani Nath and Mala Rao

Abstract

A novel bifunctional inhibitor (ATBI) from an extremophilic Bacillus sp. exhibiting an activity against phytopathogenic fungi, including Alternaria, Aspergillus, Curvularia, Colletotricum, Fusarium, and Phomopsis species, and the saprophytic fungus Trichoderma sp. has been investigated. The 50% inhibitory concentrations of ATBI ranged from 0.30 to 5.9 μg/ml, whereas the MIC varied from 0.60 to 3.5 μg/ml for the fungal growth inhibition. The negative charge and the absence of periodic secondary structure in ATBI suggested an alternative mechanism for fungal growth inhibition. Rescue of fungal growth inhibition by the hydrolytic products of xylanase and aspartic protease indicated the involvement of these enzymes in cellular growth. The chemical modification of Asp or Glu or Lys residues of ATBI by 2,4,6-trinitrobenzenesulfonic acid and Woodward's reagent K, respectively, abolished its antifungal activity. In addition, ATBI also inhibited xylanase and aspartic protease competitively, with Ki values 1.75 and 3.25 μM, respectively. Our discovery led us to envisage a paradigm shift in the concept of fungal growth inhibition for the role of antixylanolytic activity. Here we report for the first time a novel class of antifungal peptide, exhibiting bifunctional inhibitory activity

Topics: Mechanisms of Action: Physiological Effects
Publisher: American Society for Microbiology
Year: 2001
DOI identifier: 10.1128/AAC.45.7.2008-2017.2001
OAI identifier: oai:pubmedcentral.nih.gov:90593
Provided by: PubMed Central
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