Zeamatin, an antifungal protein from maize with membrane-permeabilizing activity

Abstract

A 22 kDa antifungal protein (zeamatin) was purified from Zea mays seeds. It was identified and assayed by its unusual property of acting synergistically with nikkomycin to inhibit growth of Candida albicans. Alone, it inhibited growth in suspension culture of C. albicans, Neurospora crassa and Trichoderma reesei. Zeamatin contained no detectable chitinase, 1,3-P-glucanase or ribosome-inactivating protein activity, enzymes present in a variety of plants that have been shown to have antifungal properties. At low concentrations zeamatin caused the rapid release of cytoplasmic material from C. albicans and N. crassa. This was confirmed microscopically by observing zeamatin-induced hyphal rupture of these fungi. These results suggest that zeamatin permeabilizes the fungal plasma membrane. We believe zeamatin to be a representative of a previously unrecognized class of plant antifungal proteins.

Stress proteins on the yeast cell surface determine resistance to osmotin, a plant antifungal protein

“…It has been proposed that the antifungal activity of osmotin and zeamatin, a PR-5 protein from maize, is the result of fungal membrane permeabilization due to interactions between the plasma membrane of sensitive fungi and putative pore-forming domains in these proteins (4,5,21). Our results indicate that the plasma membrane of resistant fungal cells may also be targeted by tobacco osmotin because spheroplasts derived from resistant yeast cells are as susceptible to the cytotoxic effect of osmotin as those from sensitive cells.…”

“…6). Likely, the cell wall-localized Pir proteins can affect the ability of osmotin to reach and permeabilize the plasma membrane, the apparent target for osmotin action (1,4,21). Two models are possible that account for our results.…”

“…However, the same batches of proteins were active against other fungal species tested, such as Verticillium dahliae and Trichoderma longibrachiatum (data not shown). It has been proposed that the antifungal activity of osmotin and zeamatin, a PR-5 protein from maize, is the result of fungal membrane permeabilization due to interactions between the plasma membrane of sensitive fungi and putative pore-forming domains in these proteins (4,5,21). Osmotins isolated from tobacco and A. nummularia also differed greatly in their toxicity toward spheroplast (Fig.…”

“…Leaves of transgenic potato plants expressing tobacco osmotin exhibited partial resistance to Phytophtora infestans (3), demonstrating that PR-5 proteins can be used as a source of resistance to fungal infection. The fungal growth inhibition by osmotin and zeamatin, a maize PR-5 protein, correlated with plasma membrane permeabilization and dissipation of the membrane potential (4,5), suggesting a physical interaction between PR-5 proteins and the plasma membrane of sensitive fungi, but the precise mechanism of cytotoxicity remains unknown.…”

Purification, characterization of a CkChn134 protein from Cynanchum komarovii seeds and synergistic effect with CkTLP against Verticillium dahliae

“…12,28 Although, a little known the synergistic mechanism of chitinase and thaumatin-like genes, they degrade the structural components of fungal cell or include alterations in fungal cell membrane integrity to inhibit the fungal cell growth. [29][30][31][32] The CkTLP protein from C. komarovii was located in the extracellular space/cell wall 13 and the CkChn134 had same distribution in plant, it showed the two proteins accumulated in the extracellular space/cell wall in plant to inhibit the invasion and spread of fungal pathogens, which may potentially be a significant reason for synergistic protective interaction of the two proteins in transgenic cotton against V. dahliae.…”