Conditional expression of harpinPsscauses yeast cell death that shares features of cell death pathway with harpinPss-mediated plant hypersensitive response (HR) |
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Authors: | Appa Rao Podile Hao-Jan Lin Vanisree Staniforth Paranthaman Sripriya Long-Fang Oliver Chen Teng-Yung Feng |
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Institution: | a Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, 500 046, India;b Institute of Botany, Academia Sinica, Nankang, Taipei, 11529, Taiwan |
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Abstract: | Conditional expression of harpinPsscauses yeast cell death that shares features of cell death pathway with harpinPss-mediated plant hypersensitive response (HR).Pseudomonas syringae pv.syringae 61 hrp Z gene encodes harpinPss, a 34.7 kD extracellular protein that elicits a hypersensitive response (HR) in plants. Conditional expression of either full-length or truncated hrp Z sequences under the GAL1 promoter caused cell death in Saccharomyces cerevisiae Y187. Plating of pYEUT- hrp Z transformants on a medium containing galactose resulted in complete inhibition of colony formation, whereas their growth on a glucose-based medium was unaffected. Western blot analysis confirmed the expression of harpinPssin yeast cells transformed with pYEUT- hrp Z and grown in galactose-containing medium. A time-dependent decline in the percentage of trypan blue-excluding cells in cultures of pYEUT- hrp Z transformants was observed when cultured on galactose-containing medium. Similarly, the number of viable cells reduced to about 50% within 6 h. There were similarities in the harpinPss-mediated cell death in plants and yeast cell death (YCD). Galactose-induced cell death in pYEUT-hrp Z transformants of S. cerevisiae Y187 was suppressed by a protein kinase inhibitor K252a (10 μ M). The viability of pYEUT- hrp Z transformants was prolonged in the presence of 100 U ml−1catalase suggesting a role for the oxidative burst in YCD that was further supported by the flow cytometric patterns of propidium iodide uptake by yeast cells. Overall, it appears that yeast provides a useful model system to understand the molecular mechanism of harpinPss-mediated cell death. |
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Keywords: | harpinPss hypersensitive response yeast cell death GAL1 promoter conditional expression plant HR cell death pathway |
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