In changing weather situations, plants need to be robust and flexible at the same time. These structural properties are anchored the cell walls: The cell wall is responsible for defining the plant’s shape, for compensating its osmotic pressure and to protect it against pathogens e.g. bacteria, viruses or fungal attacks. The cell walls of plants are largely built from polymers and the polysaccharide cellulose. As binding agents, polysaccharides have the important task to connect long-chain polymers and to build a molecular network of tiny strands, called fibrils, which contribute to the tensile strength of the plant. One of the sugar building blocks is the branched-chain monosaccharid Apiose, which got its name from the latin word „Apium“, a plant genus comprising, for instance, celeriac and parsley.
„Apiose has been the addressed by plant-biochemical research for more than a hundred years and its function in plants is still not fully understood. Besides, the mechanism, which is responsible for the production of Apiose in nature, was still unknown“, says Bernd Nidetzky, CSO of the Austrian Centre of Industrial Biotechnology (acib) and Director of the Institute of Biotechnology and Biochemical Engineering at Graz University of Technology, Austria.
One enzyme, four steps
Together with the Universities Pavia (Italy) and Barcelona (Spain) acib and TU Graz discovered, how Apiose is produced by a single enzyme called UAXS(UDP-apiose/UDP-xylose Synthase). For the first time, the scientists were able to decode the entire mechanism of this enzyme. These groundbreaking discoveries were published in the prestigious journal Nature Catalysis. „Isolated from the cress Arabidopsis thaliana, the catalyst possesses special properties: Whereas most biosynthetic processes for the manufacturing of complex molecules need several reaction steps, the UAXS-enzyme selectively catalyzes four reaction steps“, Nidetzky reveals. By doing so, the enzyme is able to break down organic carbon compounds as well as to establish new molecular compounds. This results in the change from a six ring sugar molecule (Hexose) to a structural converted five ring sugar (Pentose). By creating new organic carbon compounds, the enzyme is responsible for giving plants their strength properties.
The discovery of the enzymatic mechanism of Adipose was possible due to the interdisciplinary collaboration between the research areas enzymology and biocatalysis, structural biology and molecular modelling.
TU Graz biotechnologist Bernd Nidetzky is scientific director of the Austrian Centre of Industrial Biotechnology (acib).
Learn more about the work of Bernd Nidetzky in our face-to-face interview.
New insights in the capabilities and uses of enzymes
The unusual and highly complex reaction sequence of Apiose biosynthesis allows the enzymologists new, fascinating insights into the molecular evolution of higher plants and gives information about how certain enzymes are able to coordinate multi step processes, leading to a final product. Nidetzky: „Understanding the biogenesis of the carbohydrate Apiose in plants provides is with the basis for future industrial applications, for instance the production of valuable sugar molecules for possible products e.g. fine chemicals or novel biopharmaceuticals“.
The Austrian Centre of Industrial Biotechnology (acib) develops new processes for industry (the biotech, chemistry and pharmaceutical sectors) that are more economically friendly and economically efficient. In its work, the centre of competence takes nature and its methods as a role model and uses nature's tools. acib, a non-profit organisation, is an international research centre for industrial biotechnology and operates institutions in Graz, Innsbruck, Tulln, Vienna (AUT), Bielefeld, Heidelberg and Hamburg (GER) and Pavia (ITA), Canterbury (NZL) and Taiwan (CHN). 150+ universities and companies are part of this partnership cooperation.
250+ acib researchers and scientists are currently involved in more than 175 research projects.
The owners of acib are the universities of Graz and Innsbruck, Graz University of Technology, the University of Natural Resources and Life Sciences, Vienna (BOKU) and Joanneum Research. acib is funded as a K2 research centre within the framework of COMET (Competence Centres for Excellent Technologies) by the Austrian Ministry for Transport, Innovation and Technology, the Austrian Ministry of Education, Science and Research, and the provinces of Styria, Vienna, Lower Austria and Tyrol. The COMET programme is managed by the Austrian Research Promotion Agency (FFG).