Characterization of prosystemin expressed in the baculovirus/insect cell system reveals biological activity of the systemin precursor.
Tomato (Lycopersicon esculentum Mill.) prosystemin in fusion with a viral signal peptide was expressed in Sf21 insect cell cultures after infection with recombinant baculoviruses. Prosystemin was purified from culture supernatants and its identity was confirmed by N-terminal sequence and mass-spectral analyses. Recombinant prosystemin was found to be equally active as compared to systemin in inducing the expression of wound-response genes in tomato plants. In cultured cells of L. peruvianum, prosystemin elicited a rapid alkalinization of the growth medium. The timing and dose-dependence of the alkalinization response were found to be identical for prosystemin and systemin, respectively. Prosystemin-triggered defense responses were inhibited by a competitive antagonist of systemin activity, indicating that the systemin sequence within the primary structure of prosystemin determines its activity.
Institute of Plant Sciences, ETH-Zürich, Switzerland.
M
M
Vetsch
I
I
Janzik
A
A
Schaller
D000818:Animals; D016367:Baculoviridae / Q000235:genetics* / Q000378:metabolism; D002478:Cells, Cultured; D018551:Solanum lycopersicum / Q000378:metabolism / Q000502:physiology; D010455:Peptides / Q000378:metabolism / Q000502:physiology; D010940:Plant Proteins / Q000096:biosynthesis / Q000502:physiology*; D018411:Spodoptera / Q000378:metabolism
D010455:Peptides; D010940:Plant Proteins; C073705:prosystemin protein, Lycopersicon esculentum; C073704:systemin