ALBA Synchrotron
Using XALOC beamline at ALBA, researchers from the Institute of Biocomputation and Physics of Complex Systems (BIFI), at the University of Zaragoza, have discovered an unexpected way in which a plant enzyme activates sugars during a fundamental biochemical reaction. The findings, published in Nature Communications, challenge long-standing assumptions about how glycosyltransferase enzymes work and provide new foundations for biotechnological innovation.
Sugar-modifying enzymes play a central role in life. They control how sugars are attached to proteins and other molecules, a process that influences cell communication, development, immunity and responses to stress. In plants, these reactions are essential for building cell walls and regulating growth, while in humans similar enzymes are linked to disease processes and the effectiveness of therapeutic antibodies. Understanding exactly how these enzymes work at the molecular level is crucial not only for basic biology, but also for improving biomedicine, agriculture and industrial biotechnology.
The study of this group from BIFI at the University of Zaragoza focuses on FUT11, a fucosyltransferase enzyme from the model plant Arabidopsis thaliana. Glycosyltransferases such as FUT11 catalyse the formation of glycosidic bonds by transferring a sugar from a donor molecule to an acceptor. Traditionally, scientists assumed that during this reaction the acceptor sugar remained largely passive, maintaining a stable shape while the enzyme activated the donor. Using high-resolution structural data collected at the XALOC beamline – one of the ALBA’s instruments for X-ray crystallography-, the researchers were able to visualise FUT11 bound to its substrates and discovered a very different picture.
The crystal structures collected at ALBA (BL13 XALOC) provided the structural framework for mechanistic interpretation, and the accompanying atomistic simulations indicated that FUT11 actively promotes a transient distortion (puckering) of the acceptor sugar ring away from its most stable chair conformation. In these simulations, the catalytic base—Glu158—acts not only as the proton abstractor but also as a conformational effector: its interactions bias the innermost GlcNAc into a reactive, puckered state that better aligns the acceptor hydroxyl for nucleophilic attack and efficient bond formation.
Beyond plant biology, the results have wider relevance. The structure of FUT11 shares important similarities with human fucosyltransferases, explaining why the plant enzyme can also act on non-native sugars. This mechanistic flexibility helps scientists understand how related enzymes evolved and how their activity might be tuned or redirected. Such knowledge is key for enzyme engineering, including the design of catalysts that produce tailor-made glycans or improve the synthesis of complex biomolecules.
This work demonstrates the unique value of ALBA as a research infrastructure for uncovering dynamic molecular processes that cannot be captured by a single technique alone.
As ALBA advances towards the ALBA II upgrade, studies of enzyme dynamics and complex biomolecular reactions are expected to benefit even further, opening new opportunities for innovation at the interface of structural biology, chemistry and life sciences.
Representation of fucosyltransferase enzyme FUT11.