GIULIETTI Ana Maria
Involvement of G-proteins in the chitosan?induced Anthraquinone production in R. tintorum
VASCONSUELO, A.; GIULIETTI, A.M.; PICCOTO, G.; BOLAND, R.
Año: 2006 vol. 128 p. 29 - 29
We have previously shown that chitosan stimulates anthraquinone synthesis in Rubia tinctorum L. cells through activation of the PLC/PKC, PI3K, MAPK and Ca2þ messenger systems. In view of this evidence, we have now investigated whether guanine nucleotide-binding G-proteins are part of the signal transduction mechanism which mediates the elicitor action. The G-protein agonists mastoparan, AlF4 ? and GTPyS increased anthraquinone levels to the same extent as chitosan. No additive effects were observed when cultured R. tinctorum cells were treated with agonist and the elicitor together. In agreement with these observations, the G-protein antagonists suramin and GDPbS abolished the increase in anthraquinone synthesis induced by chitosan. Furthermore, elicitation was not affected in the presence of pertussis toxin. Consistent with this result, when cell cultures were preincubated with a monoclonal anti-Gaq/11 antibody, the chitosan-dependent increase in anthraquinone levels was fully inhibited. Moreover, the presence of an immunoreactive protein of the expected size for Gaq/11 (42 kDa) was observed in R. tinctorum microsomal membranes by Western blot analysis using the same antibody. These results indicate that chitosan stimulates anthraquinone synthesis in R. tinctorum cells through a heterotrimeric G-protein, most likely belonging to the Gaq family.