New study captures sugar transport fundamental to plants

Date:
October 4, 2021
Source:
Aarhus University
Summary:
Researchers have just elucidated structures of a sugar transport
protein that drives transport of sugar in plants. The study provides
a comprehensive insight into sugar uptake into plant organs such
as flowers, seeds and fruit. Future research can benefit from
these discoveries to address challenges like food security through
crop improvement.



FULL STORY ==========================================================================
In plants, Sugar Transport Proteins (STPs) are key for uptake of
glucose. They are responsible for sugar import into plant organs
such as seeds, pollen and fruit and are essential for correct tissue development. Moreover, controlling sugar uptake through STPs is used
by plants as a vital defense strategy against microbial infection, by
using starvation and competition for sugar to restrict microbial growth.


==========================================================================
The results are a continuation of earlier research at Associate Professor
Bjo/ rn Panyella Pedersen's research group at the Department of Molecular Biology and Genetics. A major challenge to make progress in the field
is to obtain structures of STPs in different conformations.

PhD Student and first author Laust Bavnho/j explains: "The STPs are
highly dynamic membrane proteins that undergoes large conformational
changes during transport. This flexibility present a great challenge as conformational stabilization is needed in order to facilitate structure solution by X-ray crystallography. This challenge was exacerbated because
we needed the transporter in a very specific conformation in order to
answer our questions.

Based on our previous work, we could design mutants that worked to
destabilize an outward facing conformation. This allowed us to break
the "conformational dead water" and push our protein into a new inward
facing conformation." The new work reports two crystal structures of Arabidopsis thalianaSTP10. The structures represent two major states
needed to understand the complete picture of substrate and proton co-translocation across the cell membrane and into the cell.

Structure and dynamics hand in hand In a collaborative effort with
Professor Birgit Schio/tt's group from the Department of Chemistry at
Aarhus University, the researchers also used state- of-the-art Molecular Dynamics simulations to support the notion of proton binding employing
multiple independent approaches. The structures and Molecular Dynamics,
in combination with a comprehensive biochemical characterization of STP10, offers evidence for a sugar uptake mechanism based on a well-defined glucose-binding site linked to a clear proton-binding site. Together,
the findings provide the first evidence for the elements that are
required for the substrate transport mechanism essential for all STPs,
and other related protein families.

"Combining these methods, we were able to not only identify key
elements involved in the transport cycle within STPs but also provide
new evidence for regulatory mechanisms conserved within the sugar porter
family across all kingdoms of life," says Bjo/rn Panyella Pedersen. "We recently showed that this regulatory mechanism is also found in human
sugar transporters, and our new work support the idea of a general scheme
for kinetic control within the Sugar Porter family across evolution." Researchers at Aarhus University have just elucidated structures of a
sugar transport protein that drives transport of sugar in plants. The
study provides a comprehensive insight into sugar uptake into plant
organs such as flowers, seeds and fruit. Future research can benefit
from these discoveries to address challenges like food security through
crop improvement.

========================================================================== Story Source: Materials provided by Aarhus_University. Original written
by Lisbeth Heilesen.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Laust Bavnho/j, Peter Aasted Paulsen, Jose C. Flores-Canales, Birgit
Schio/tt, Bjo/rn Panyella Pedersen. Molecular mechanism of sugar
transport in plants unveiled by structures of glucose/H symporter
STP10.

Nature Plants, 2021; DOI: 10.1038/s41477-021-00992-0 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/10/211004104137.htm

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