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Characterization, localization, and seasonal changes of the sucrose transporter FeSUT1 in the phloem of Fraxinus excelsior.

Öner-Sieben S, Rappl C, Sauer N, Stadler R, Lohaus G - J. Exp. Bot. (2015)

Bottom Line: The localization and expression pattern point towards functions of FeSUT1 in phloem loading of sucrose as well as in sucrose retrieval.The elevated expression level of FeSUT1 indicated an increased apoplastic carbon export activity from the leaves during spring and late autumn.It is hypothesized that the importance of apoplastic loading is high under low-sucrose conditions and that the availability of two different phloem-loading mechanisms confers advantages for temperate woody species like F. excelsior.

View Article: PubMed Central - PubMed

Affiliation: Molekulare Pflanzenforschung/Pflanzenbiochemie (Botanik), Bergische Universität Wuppertal, Gaußstraße 20, D-42119 Wuppertal, Germany.

No MeSH data available.


Related in: MedlinePlus

(A) Uptake of 14C-sucrose into SEY2102 yeast cells that expressed FeSUT1. The exogenous sucrose concentration was 1mM and measurements were conducted three times with three different transformants. (B) Hanes-Woolf plot for the calculation of the Km-value of FeSUT1. The initial sucrose concentrations to the reaction velocities are plotted against the sucrose concentrations.
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Figure 1: (A) Uptake of 14C-sucrose into SEY2102 yeast cells that expressed FeSUT1. The exogenous sucrose concentration was 1mM and measurements were conducted three times with three different transformants. (B) Hanes-Woolf plot for the calculation of the Km-value of FeSUT1. The initial sucrose concentrations to the reaction velocities are plotted against the sucrose concentrations.

Mentions: Recent studies identified a Group II SUT from source leaves of F. excelsior (Öner-Sieben and Lohaus, 2014; Supplementary Fig. S1). This transport protein was examined to see if it is involved in the observed accumulation of sucrose in the phloem. To evaluate the properties of FeSUT1, the transporter was analysed in a yeast strain previously used for functional analysis of plant SUTs (Gahrtz et al., 1994; Sauer and Stolz, 1994). The FeSUT1 cDNA was cloned in sense and antisense direction into the shuttle vector NEV-E and the resulting constructs were used to transform the yeast strain SEY2102. Yeasts containing the sense plasmid constructs (FeSUT1+) transported 14C-sucrose at high rates whereas sucrose uptake in the negative control (FeSUT1−) was negligibly low (Fig. 1A). This result proved that FeSUT1 is in fact a functional sucrose transport protein. Kinetic analyses of 14C-sucrose uptake by yeast cells expressing FeSUT1 revealed an apparent Km-value for sucrose of 2.9±0.4mM at pH 5.5 (Fig. 1B).


Characterization, localization, and seasonal changes of the sucrose transporter FeSUT1 in the phloem of Fraxinus excelsior.

Öner-Sieben S, Rappl C, Sauer N, Stadler R, Lohaus G - J. Exp. Bot. (2015)

(A) Uptake of 14C-sucrose into SEY2102 yeast cells that expressed FeSUT1. The exogenous sucrose concentration was 1mM and measurements were conducted three times with three different transformants. (B) Hanes-Woolf plot for the calculation of the Km-value of FeSUT1. The initial sucrose concentrations to the reaction velocities are plotted against the sucrose concentrations.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4507781&req=5

Figure 1: (A) Uptake of 14C-sucrose into SEY2102 yeast cells that expressed FeSUT1. The exogenous sucrose concentration was 1mM and measurements were conducted three times with three different transformants. (B) Hanes-Woolf plot for the calculation of the Km-value of FeSUT1. The initial sucrose concentrations to the reaction velocities are plotted against the sucrose concentrations.
Mentions: Recent studies identified a Group II SUT from source leaves of F. excelsior (Öner-Sieben and Lohaus, 2014; Supplementary Fig. S1). This transport protein was examined to see if it is involved in the observed accumulation of sucrose in the phloem. To evaluate the properties of FeSUT1, the transporter was analysed in a yeast strain previously used for functional analysis of plant SUTs (Gahrtz et al., 1994; Sauer and Stolz, 1994). The FeSUT1 cDNA was cloned in sense and antisense direction into the shuttle vector NEV-E and the resulting constructs were used to transform the yeast strain SEY2102. Yeasts containing the sense plasmid constructs (FeSUT1+) transported 14C-sucrose at high rates whereas sucrose uptake in the negative control (FeSUT1−) was negligibly low (Fig. 1A). This result proved that FeSUT1 is in fact a functional sucrose transport protein. Kinetic analyses of 14C-sucrose uptake by yeast cells expressing FeSUT1 revealed an apparent Km-value for sucrose of 2.9±0.4mM at pH 5.5 (Fig. 1B).

Bottom Line: The localization and expression pattern point towards functions of FeSUT1 in phloem loading of sucrose as well as in sucrose retrieval.The elevated expression level of FeSUT1 indicated an increased apoplastic carbon export activity from the leaves during spring and late autumn.It is hypothesized that the importance of apoplastic loading is high under low-sucrose conditions and that the availability of two different phloem-loading mechanisms confers advantages for temperate woody species like F. excelsior.

View Article: PubMed Central - PubMed

Affiliation: Molekulare Pflanzenforschung/Pflanzenbiochemie (Botanik), Bergische Universität Wuppertal, Gaußstraße 20, D-42119 Wuppertal, Germany.

No MeSH data available.


Related in: MedlinePlus