Automated chip-nanoelectrospray mass spectrometry for glycourinomics in Schindler disease type I

Schistosoma mansoni α-N-acetylgalactosaminidase (SmNAGAL) regulates coordinated parasite movement and egg production

α-galactosidase (α-GAL) and α-N-acetylgalactosaminidase (α-NAGAL) are two glycosyl hydrolases responsible for maintaining cellular homeostasis by regulating glycan substrates on proteins and lipids. Mutations in the human genes encoding either enzyme lead to neurological and neuromuscular impairments seen in both Fabry- and Schindler/Kanzaki- diseases. Here, we investigate whether the parasitic blood fluke Schistosoma mansoni, responsible for the neglected tropical disease schistosomiasis, also contains functionally important α-GAL and α-NAGAL proteins. As infection, parasite maturation and host interactions are all governed by carefully-regulated glycosylation processes, inhibiting S. mansoni's α-GAL and α-NAGAL activities could lead to the development of novel chemotherapeutics. Sequence and phylogenetic analyses of putative α-GAL/α-NAGAL protein types showed Smp_089290 to be the only S. mansoni protein to contain the functional amino acid residues necessary for α-GAL/α-NAGAL substrate cleavage. Both α-GAL and α-NAGAL enzymatic activities were higher in females compared to males (p<0.05; α-NAGAL > α-GAL), which was consistent with smp_089290's female biased expression. Spatial localisation of smp_089290 revealed accumulation in parenchymal cells, neuronal cells, and the vitellaria and mature vitellocytes of the adult schistosome. siRNA-mediated knockdown (>90%) of smp_089290 in adult worms significantly inhibited α-NAGAL activity when compared to control worms (siLuc treated males, p<0.01; siLuc treated females, p<0.05). No significant reductions in α-GAL activities were observed in the same extracts. Despite this, decreases in α-NAGAL activities correlated with a significant inhibition in adult worm motility as well as in egg production. Programmed CRISPR/Cas9 editing of smp_089290 in adult worms confirmed the egg reduction phenotype. Based on these results, Smp_089290 was determined to act predominantly as an α-NAGAL (hereafter termed SmNAGAL) in schistosome parasites where it participates in coordinating movement and oviposition processes. Further characterisation of SmNAGAL and other functionally important glycosyl hydrolases may lead to the development of a novel anthelmintic class of compounds.

Microfluidics-Mass Spectrometry of Protein-Carbohydrate Interactions: Applications to the Development of Therapeutics and Biomarker Discovery

The functional interactions of carbohydrates and their protein receptors are the basis of biological events critical to the evolution of pathological states. Hence, for the past years, such interactions have become the focus of research for the development of therapeutics and discovery of novel glycan biomarkers based on their binding affinity. Due to the high sensitivity, throughput, reproducibility, and capability to ionize minor species in heterogeneous mixtures, microfluidics-mass spectrometry (MS) has recently emerged as a method of choice in protein-glycan interactomics. In this chapter, a straightforward microfluidics-based MS methodology for the assessment of protein-glycan interactions is presented. The general protocol encompasses: (1) submission of the interacting partners to a binding assay under conditions mimicking the in vivo environment; and (2) screening of the reaction products and their structural characterization by fully automated chip-nanoelectrospray (nanoESI) MS and multistage MS. The first section of the chapter is devoted to describing a method that enables the study of protein-oligosaccharide interactions by chip-nanoESI quadrupole time-of-flight (QTOF) MS and top-down complex analysis by collision-induced dissociation (CID). This section provides the protocol for the determination of the complex formed by standard β-lactoglobulin (BLG) with maltohexaose (Glc₆) and recommends as a concrete application the study of the interaction between BLG extracted from human milk with Glc₆, considered a ligand able to reduce the allergenicity of this protein. The second part is dedicated to presenting the protocols for the binding assay followed by chip-nanoESI ion trap (ITMS) and electron transfer dissociation (ETD) in combination with CID for protein-ganglioside interactions, using as an example the B subunit of cholera toxin (Ctb5) in interaction with comercially available GM1 species. The methodology described may be successfully applied to native ganglioside mixtures from human brain, in particular for discovery of biomarkers on the basis of their binding affinity.

Sustainable Nanosystem Development for Mass Spectrometry

Nowadays, considerable efforts are invested into development of sustainable nanosystems as front end technology for either Electrospray Ionization (ESI) or Matrix-Assisted Laser Desorption/Ionization (MALDI) mass spectrometry (MS). Since their first introduction in MS, nanofluidics demonstrated a high potential to discover novel biopolymer species. These systems confirmed the unique ability to offer structural elucidation of molecular species, which often represent valuable biomarkers of severe diseases. In view of these major advantages of nanofluidics-MS, this chapter reviews the strategies, which allowed a successful development of nanotechnology for MS and the applications in biological and clinical research. The first part will be dedicated to the principles and technical developments of advanced nanosystems for electrospray and MALDI MS. The second part will highlight the most important applications in clinical proteomics and glycomics. Finally, this chapter will emphasize that advanced nanosystems-MS has real perspectives to become a routine method for early diagnosis of severe pathologies.

Application of ion mobility tandem mass spectrometry to compositional and structural analysis of glycopeptides extracted from the urine of a patient diagnosed with Schindler disease

RATIONALE

Schindler disease is caused by the deficient activity of α-N-acetylgalactosaminidase, which leads to an abnormal accumulation of O-glycopeptides in tissues and body fluids. In this work the Schindler condition is for the first time approached by ion mobility (IMS) tandem mass spectrometry (MS/MS), for determining urine glycopeptide fingerprints and discriminate isomeric structures.

METHODS

IMS-MS experiments were conducted on a Synapt G2s mass spectrometer operating in negative ion mode. A glycopeptide mixture extracted from the urine of a patient suffering from Schindler disease was dissolved in methanol and infused into the mass spectrometer by electrospray ionization using a syringe-pump system. MS/MS was performed by collision-induced dissociation (CID) at low energies, after mobility separation in the transfer cell. Data acquisition and processing were performed using MassLynx and Waters Driftscope software.

RESULTS

IMS-MS data indicated that the attachment of one or two amino acids to the carbohydrate backbone has a minimal influence on the molecule conformation, which limits the discrimination of the free oligosaccharides from the glycosylated amino acids and dipeptides. The structural analysis by CID MS/MS in combination with IMS-MS of species exhibiting the same m/z but different configurations demonstrated for the first time the presence of positional isomers for some of the Schindler disease biomarker candidates.

CONCLUSIONS

The IMS-MS and CID MS/MS platform was for the first time optimized and applied to Schindler disease glycourinome. By this approach the separation and characterization of Neu5Ac positional isomers was possible. IMS CID MS/MS showed the ability to determine the type of the glycopeptide isomers from a series of possible candidates.

Identification and structural characterization of novel O- and N-glycoforms in the urine of a Schindler disease patient by Orbitrap mass spectrometry

Schindler disease is an inherited metabolic disorder caused by the deficient activity of α-N-acetylgalactosaminidase enzyme. An accurate diagnosis requires, besides clinical examination, complex and costly biochemical and molecular genetic tests. In the last years, mass spectrometry (MS) based on nanofluidics and high-resolution instruments has become a successful alternative for disease diagnosis based on the investigation of O-glycopeptides in patient urine. A complex mixture of glycoforms extracted from the urine of a 3-year-old patient was investigated by Orbitrap MS equipped with Nanospray Flex Ion Source in the negative ion mode. For structural characterization of several molecular species, collision-induced dissociation MS² -MS³ was carried out using collision energy values within 20-60 eV range. By our approach, 39 novel species associated to this condition were identified, among which O-glycopeptides, free O-glycans and one structure corresponding to an N-glycan never characterized in the context of Schindler disease. The experiments conducted at a resolution of 60 000 allowed the discrimination and identification of a total number of 69 different species with an average mass accuracy of 9.87 ppm, an in-run reproducibility of almost 100%, an experiment-to-experiment and day-to-day reproducibility of about 95%. This study brings contributions in the diagnosis of Schindler disease through the elucidation of potential biomarker species in urine. Our multistage MS results completed with 39 new glycoforms the inventory of potential biomarker structures associated to Schindler disease. For the first time, an N-glycan was identified and structurally characterized in Schindler patient urine, which opens new research directions in the field. Copyright © 2015 John Wiley & Sons, Ltd.