Proceedings of the XLVII Italian Society of Agricultural Genetics - SIGA Annual Congress

Verona, Italy - 24/27 September, 2003

ISBN 88-900622-4-X

Poster Abstract - 5.05

IS S-NITROSYLATION A SIGNALING MECHANISM IN PLANTS?

M.C. ROMERO-PUERTAS*, M. PERAZZOLLI*^,**, M. DE STEFANO*, M. DELLEDONNE*

*) Università degli Studi di Verona, Dipartimento Scientifico e Tecnologico, Strada Le Grazie 15, 37134 Verona

**) Istituto di Botanica e Genetica Vegetale, Università Cattolica S.C., Via Emilia Parmense 84, 29100 Piacenza

S-nitrosylation, nitric oxide, signaling

Recent studies point out the potential role of NO as a signal in plants (1). Moreover, NO acts as a key signal in plant resistance to incompatible pathogens by triggering resistance-associated cell death (2).

During plant-pathogen interactions, NO activates the expression of several defence genes (i.e. pathogenesis-related genes, phenylalanine ammonialyase, chalcone synthase). In this context, gene induction is achieved through a cGMP-dependent signaling cascade activated by NO (3). A direct action of NO was proposed to regulate the accumulation of reactive oxygen species (ROS) during plant-pathogen interactions by modulating antioxidant enzyme activities (4).

Recent evidence indicates that NO in animal tissues regulates this diverse biologic processes by directly modifying proteins. NO and related species can oxidize, nitrate or nitrosylate proteins (5). Nitrosylation refers to the binding of a NO group to a transition metal or cysteine residue, is a reversible modification and plays a central role in NO-mediated signalling (5). Accumulating data suggest that many proteins are nitrosylated by NO (for over 100 representative examples are available on line at http://www.cell.com/cgi/content/full/106/6/675/DC1) and that in fact nitrosylation may be a ubiquitous posttranslational modification regulating protein function. Indeed, nitrosylation shares many features in common with phosphorylation, the prototypic posttranslational modification involved in signal transduction regulation. Both modifications are reversible and specific, allowing cells to flexibly and precisely modify protein function in response to environmental signals.

The existence of protein nitrosylation in plants has been studied. Crude extracts from Arabidopsis leaves were subjected to analysis of their nitrosylation patterns by performing SDS-PAGE and Western blotting using Nitro-Glo kit (Perkin-Elmer). Numerous nitrosylated proteins were found by this method in plant tissue. Further studies will be focused on changes in the nitrosylation pattern under different biotic and abiotic stress situations, in order to see whether or not protein nitrosylation is a signal transduction mechanism during plant-pathogen interaction.

1. Wendehenne et al., 2001

2. Delledonne et al., 1998

3. Durner et al., 1998

4. Clark et al., 2000

5. Stamler et al., 2001