Identification of O-GlcNAc and O-Fucose binding lectins in Arabidopsis thaliana
Abstract
O-Glycosylation of nuclear and cytosolic proteins is a very common post-translational modification (PTM), contributing to the complexity in the function and regulation of proteins. In contrast to other types of glycosylation, a single sugar residue - either N-acetylglucosamine (GlcNAc) or fucose - is attached to serine or threonine residues of a high number of very diverse proteins. O-GlcNAc modification is well characterized in animals, where it is essential for development and decisively involved in a range of signaling events, often affecting protein interactions and competing with other O-linked PTMs. While animals carry only one O-GlcNAc-transferase (OGT), plants have two structurally related O-glycosyltransferases, competing for the same targets: the O-GlcNAc transferase SECRET AGENT (SEC) and the protein O-fucosyltransferase SPINDLY (SPY) show high sequence homology, but their activity can have opposite effects on their target proteins. This mechanism of counteracting O-glycosyltransferases seems to be specific for plants. Its importance for plant development is apparent from genetic analysis, as a double knockout of the two enzymes is embryonic lethal. However, clearly more research is necessary in order to understand the molecular mechanisms underlying O-glycosylation in plants. We are currently working on this topic using a combination of different approaches, including identification of targets of SPY and SEC, as well as interacting proteins. Among the proteins identified in these experiments was a group of jacalin-like lectins, that potentially interact with O-glycosylated proteins and might represent an additional regulatory layer by specifically recognizing O-GlcNAc and/or O-fucose-modified proteins, thereby mediating the molecular effects of O-glycosylation. The current proposal is therefore focused on characterization of these jacalin-like lectins and their interaction with glycoproteins. In addition, I am proposing an unbiased approach to identify new plant lectins specific for this type of O-glycosylation. The suggested experiments include testing the interaction of identified lectins with O-glycosylated proteins and determining their specificity for certain carbohydrates on glycan arrays. In parallel, the biological role of these lectins will be determined by phenotypic analysis of mutants as well as standard molecular biology techniques. This approach might elucidate the role of previously uncharacterized lectins, potentially involved in fine-tuning the effects of O-glycosylation, for instance in response to environmental stimuli. On the other hand, the identification and characterization of new lectins might be the basis for the development of better tools to analyze O-glycosylation specifically, in plants as well as other organisms.
Publikationen
Project staff
Doris Lucyshyn
Mag. Dr. Doris Lucyshyn
doris.lucyshyn@boku.ac.at
Tel: +43 1 47654-94035, 94250
Project Leader
01.01.2019 - 31.05.2023
Parisa Fakhrian
Parisa Fakhrian MSc.
parisa.fakhrian@boku.ac.at
Project Staff
01.01.2019 - 31.05.2023
Krishna Vasant Mutanwad
Dr. Krishna Vasant Mutanwad
krishna.mutanwad@boku.ac.at
Project Staff
01.01.2019 - 31.05.2023