ISSN:
1399-3054
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
Intracellular transport of the ethylene precursor, I-aminocyclopropane-1-carboxylic acid (ACC) can change the ACC concentration in cell compartments and impact ethylene biosynthesis. Transport of ACC into isolated maize (Zea mays L.) mesophyll vacuoles was studied by silicon layer flotation filtering. The transport of ACC across the tonoplast was stimulated 2. 4- to 8. 1-fold by 5 mM MgATP, showed saturation kinetics with an apparent Km for ACC of 20 μM, and was optimal at 25°C. Transport of ACC was sensitive to the pH of the medium, falling as external pH rose. Effectors known to inhibit proton-translocating ATPases (N, N-dicyclohexylcarbodiimide) and to collapse the electrical (thiocyanate, valinomycin) and chemical (carbonylcyanide m-chlorophenylhydrazone, gramicidin) potential gradients for protons across the tonoplast all reduced ACC transport. The nonhydrolyzable MgATP analog. Mg adenylyl-imidodiphosphate, stimulated ACC transport as effectively as MgATP. Other nucleotides (MgADP, MgCTP, MgUTP, MgGTP) and MgPPi had little or no effect. These results suggest that ACC uptake into isolated maize mesophyll vacuoles is carrier mediated, is dependent upon an electrochemical potential gradient for protons and is specifically regulated, but not necessarily energized, by MgATP
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1399-3054.1993.tb02504.x
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