Transport of 1-kestose across the tonoplast of Jerusalem artichoke tubers.
The capacity for 1-kestose uptake into the vacuole of fructan storing Jerusalem artichoke tubers was investigated. 1-kestose serves both as building block for fructan initiation and as a fructose donor for chain elongation. Tonoplast vesicles were isolated from actively storing tubers, and their vesicles were capable of transporting sucrose in a manner indicative of a sucrose/H(+) antiport. Under similar conditions, 1-kestose was not taken up by vesicles energized by either a pH jump or in the presence of ATP. When added together at 2 mM, sucrose uptake was not affected by the presence of 1-kestose. The data argues against the possible synthesis of 1-kestose in the cytosol and subsequent transport to the vacuole. The data also presents definite evidence for the existence a mechanism for sucrose accumulation in fructan storing vacuoles.
Pontis
Horacio G
HG
Fundación para Investigaciónes Biológicas Aplicadas, Vieytes 3103, Casilla de Correo 1348, 7600 Mar del Plata, Pcia., Buenos Aires, Argentina.
González
Pedro
P
Etxeberria
Ed
E
D001692:Biological Transport; D006368:Helianthus / Q000201:enzymology / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008856:Microscopy, Fluorescence; D015388:Organelles / Q000201:enzymology / Q000378:metabolism*; D013395:Sucrose / Q000378:metabolism; D014312:Trisaccharides / Q000378:metabolism*; D025262:Vacuolar Proton-Translocating ATPases / Q000378:metabolism
D014312:Trisaccharides; C072433:1-kestose; D013395:Sucrose; D025262:Vacuolar Proton-Translocating ATPases