Glycan structural determination of glycoproteins from the midgut of Spodoptera frugiperda

Abstract

Glycosylation is likely the most common post-translational modification in proteins. The protein-attached glycan may present a variety of functions ranging from host-pathogen interaction to cell adhesion and immune response. In the last decade, mass spectrometry-based glycomics/glycoproteomics appeared as an emergent and important research field due to advances in mass spectrometers technology, which allowed the use of this technique to obtain carbohydrate structural information. However, in insects, only little structural information about glycans attached to proteins is available. Most part of the knowledge is regarding to comparisons with human ortholog genes that express glycosyltransferases and lectins, with a huge lack in glycan structures which certainly play important roles in the insect physiology. For instance, many proteins present in the midgut microvilli of insects are glycosylated. Among them there are proteins which are targeted by Cry endotoxins produced by the enthomopathogenic bacteria Bacillus thuringiensis. These protein targets, named Cry toxin receptors (CTR), have their glycans recognized by Cry endotoxins as an important part of the process. So far, there is no structural information about glycans present in CTR. The use of Cry toxins is a good way to control many agricultural pests, including Spodoptera frugiperda, since these toxins are innocuous to other organisms like plants and vertebrates. Thus, the objective of this study is the characterization by glycomics and glycoproteomics of CTRs and other GPI (glycosylphosphatidylinositol)-anchored proteins present in the midgut microvilli of the agricultural pest Spodoptera frugiperda. As a secondary goal, the same approach will be used for obtaining the structure of glycans present in mucin-like proteins of Spodoptera frugiperda midgut, opening the doors for comparisons between insect and human mucins, since the latter may be used for biotechnological purpose such as biomaterial coating. (AU)