Journal Article

Pn-AMP1, a Plant Defense Protein, Induces Actin Depolarization in Yeasts

Ja Choon Koo, Boyoung Lee, Michael E. Young, Sung Chul Koo, John A. Cooper, Dongwon Baek, Chae Oh Lim, Sang Yeol Lee, Dae-Jin Yun and Moo Je Cho

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 45, issue 11, pages 1669-1680
Published in print November 2004 | ISSN: 0032-0781
Published online November 2004 | e-ISSN: 1471-9053 | DOI:
Pn-AMP1, a Plant Defense Protein, Induces Actin Depolarization in Yeasts

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry


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Pn-AMP1, Pharbitis nil antimicrobial peptide 1, is a small cysteine-rich peptide implicated in host-plant defense. We show here that Pn-AMP1 causes depolarization of the actin cytoskeleton in Saccharomyces cerevisiae and Candida albicans. Pn-AMP1 induces rapid depolarization of actin cables and patches within 15 min. Increased osmolarity or temperature induces transient actin depolarization and results in increased sensitivity to Pn-AMP1, while cells conditioned to these stresses show less sensitivity. Mutations in components of a cell wall integrity pathway (Wsc1p, Rom2p, Bck1p and Mpk1p), which regulate actin repolarization, result in increased sensitivity to Pn-AMP1. A genetic screen reveals that mutations in components of the α-1,6-mannosyltransferase complex (Mnn10p, Mnn11p and Och1p), which regulate mannosylation of cell wall proteins, confer resistance to Pn-AMP1. FITC-conjugated Pn-AMP1 localizes to the outer surface of the cell with no significant staining observed in spheroplasts. Taken together, these results indicate that cell wall proteins are determinants of resistance to Pn-AMP1, and the ability of a plant defense protein to induce actin depolarization is important for its antifungal activity.

Keywords: Keywords: Actin cytoskeleton — Cell wall integrity pathway — Hevein-like peptide — Plant antifungal protein — Yeast.; Abbreviations: DAPI, 4′,6-diamidino-2-phenylindole; IC50, concentrations required for 50% growth inhibition; MAP, mitogen-activated protein; Pn-AMP, Pharbitis nil antimicrobial peptide; Rh-Ph, rhodamine-labeled phalloidin; SEM, scanning electron microscopy.

Journal Article.  7903 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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