1.The queuine micronutrient: charting a course from microbe to man.
Fergus C;Barnes D;Alqasem MA;Kelly VP Nutrients. 2015 Apr 15;7(4):2897-929. doi: 10.3390/nu7042897.
Micronutrients from the diet and gut microbiota are essential to human health and wellbeing. Arguably, among the most intriguing and enigmatic of these micronutrients is queuine, an elaborate 7-deazaguanine derivative made exclusively by eubacteria and salvaged by animal, plant and fungal species. In eubacteria and eukaryotes, queuine is found as the sugar nucleotide queuosine within the anticodon loop of transfer RNA isoacceptors for the amino acids tyrosine, asparagine, aspartic acid and histidine. The physiological requirement for the ancient queuine molecule and queuosine modified transfer RNA has been the subject of varied scientific interrogations for over four decades, establishing relationships to development, proliferation, metabolism, cancer, and tyrosine biosynthesis in eukaryotes and to invasion and proliferation in pathogenic bacteria, in addition to ribosomal frameshifting in viruses. These varied effects may be rationalized by an important, if ill-defined, contribution to protein translation or may manifest from other presently unidentified mechanisms.
2.Multi-Stage Mass Spectrometry Analysis of Sugar-Conjugated β-Turn Structures to be Used as Probes in Autoimmune Diseases.
Giangrande C;Auberger N;Rentier C;Papini AM;Mallet JM;Lavielle S;Vinh J J Am Soc Mass Spectrom. 2016 Apr;27(4):735-47. doi: 10.1007/s13361-015-1321-9. Epub 2016 Jan 4.
Synthetic sugar-modified peptides were identified as antigenic probes in the context of autoimmune diseases. The aim of this work is to provide a mechanistic study on the fragmentation of different glycosylated analogs of a synthetic antigenic probe able to detect antibodies in a subpopulation of multiple sclerosis patients. In particular the N-glucosylated type I' β-turn peptide structure called CSF114(Glc) was used as a model to find signature fragmentations exploring the potential of multi-stage mass spectrometry by MALDI-LTQ Orbitrap. Here we compare the fragmentation of the glucosylated form of the synthetic peptide CSF114(Glc), bearing a glucose moiety on an asparagine residue, with less or non- immunoreactive forms, bearing different sugar-modifications, such as CSF114(GlcNAc), modified with a residue of N-acetylglucosamine, and CSF114[Lys(7)(1-deoxyfructopyranosyl)], this last one modified with a 1-deoxyfructopyranosyl moiety on a lysine at position 7.
3.N-Glycosyltransferase from Aggregatibacter aphrophilus synthesizes glycopeptides with relaxed nucleotide-activated sugar donor selectivity.
Kong Y;Li J;Hu X;Wang Y;Meng Q;Gu G;Wang PG;Chen M Carbohydr Res. 2018 Jun 15;462:7-12. doi: 10.1016/j.carres.2018.03.008. Epub 2018 Mar 19.
N-Glycosyltransferase (NGT) is an inverting glycosyltransferase for an unusual pathway of N-linked protein glycosylation and glycosylates polypeptides in the consensus sequon (N-(X≠P)-T/S) with hexose monosaccharides. Here, we expressed and characterized a novel N-glycosyltransferase from Aggregatibacter aphrophilus (named AaNGT). RP-HPLC and Mass Spectrometry were used to assay and quantify glycopeptide formation by AaNGT and determine its substrate specificities. AaNGT could utilize a variety of nucleotide-activated sugar donors, including UDP-Glc, UDP-Gal, UDP-Xyl, GDP-Glc, dGDP-Glc and UDP-GlcN, to glycosylate the tested peptides. To the best of our knowledge, AaNGT was the first identified natural glycosyltransferase able to transfer GlcN moiety onto asparagine residues. AaNGT also exhibited a different position-specific residue preference of substrate peptides from the NGT of Actinobacillus pleuropneumoniae (ApNGT). In vitro assays with diverse synthesized peptides revealed that AaNGT preferred different peptide substrates from ApNGT.
