Maize response to acute arsenic toxicity as revealed by proteome analysis of plant shoots

Aerial parts (shoots) of maize seedlings fed hydroponically with 300 mu M sodium arsenate [As(V)] or 250 mM sodium arsenite [As(III)] for 24 h were analyzed for differentially expressed proteins by 2-DE and digital image analysis. About 15% of total detected proteins (74 out of 500) were up-or, mainly, down-regulated by arsenic, among which 14 were selected as being those most affected by the metalloid. These proteins were analyzed by MALDI-TOF MS and 7 of them were identified: translation initiation factor eIF-5A, ATP synthase, cysteine synthase, malate dehydrogenase, protein kinase C inhibitor, Tn10 transposase-like protein, and guanine nucleotide binding protein. Each of these proteins was completely repressed by As(V) and/or As(III), except protein kinase C inhibitor, which was newly detected after exposure to As(V).