The novel chloroplast glucose transporter pGlcT2 affects adaptation to extended light periods

authored by

Marzieh Valifard, Alisdair R. Fernie, Anastasia Kitashova, Thomas Nägele, Rebekka Schröder, Melissa Meinert, Benjamin Pommerrenig, Denise Mehner-Breitfeld, Claus Peter Witte, Thomas Brüser, Isabel Keller, H. Ekkehard Neuhaus

Abstract

Intracellular sugar compartmentation is critical in plant development and acclimation to challenging environmental conditions. Sugar transport proteins are present in plasma membranes and in membranes of organelles such as vacuoles, the Golgi apparatus, and plastids. However, there may exist other transport proteins with uncharacterized roles in sugar compartmentation. Here we report one such novel transporter of the Monosaccharide Transporter Family, the closest phylogenetic homolog of which is the chloroplast-localized glucose transporter pGlcT and that we therefore term plastidic glucose transporter 2 (pGlcT2). We show, using gene-complemented glucose uptake deficiency of an Escherichia coli ptsG/manXYZ mutant strain and biochemical characterization, that this protein specifically facilitates glucose transport, whereas other sugars do not serve as substrates. In addition, we demonstrate pGlcT2-GFP localized to the chloroplast envelope and that pGlcT2 is mainly produced in seedlings and in the rosette center of mature Arabidopsis plants. Therefore, in conjunction with molecular and metabolic data, we propose pGlcT2 acts as a glucose importer that can limit cytosolic glucose availability in developing pGlcT2-overexpressing seedlings. Finally, we show both overexpression and deletion of pGlcT2 resulted in impaired growth efficiency under long day and continuous light conditions, suggesting pGlcT2 contributes to a release of glucose derived from starch mobilization late in the light phase. Together, these data indicate the facilitator pGlcT2 changes the direction in which it transports glucose during plant development and suggest the activity of pGlcT2 must be controlled spatially and temporarily in order to prevent developmental defects during adaptation to periods of extended light.

Organisation(s)

Institute of Plant Nutrition
Institute of Microbiology

External Organisation(s)

University of Kaiserslautern
Max Planck Institute of Molecular Plant Physiology (MPI-MP)
Ludwig-Maximilians-Universität München (LMU)

Type

Article

Journal

Journal of Biological Chemistry

Volume

299

ISSN

0021-9258

Publication date

06.2023

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Biochemistry, Molecular Biology, Cell Biology

Electronic version(s)

https://doi.org/10.1016/j.jbc.2023.104741 (Access: Closed)