Project description:In vitro and tranfection analysis of death domain containing proteins to assess the ability of NleB2 to glycosylate these proteins.
Project description:Proteomic investigation on the glycosylation substrates and proteome effects of altering neisserial OTases within the proteome of N. gonorrhoeae MS11
Project description:The haematopoietic cytokine thrombopoietin (Tpo) is the primary regulator of megakaryocyte and platelet numbers and is required for maintenance of the haematopoetic stem cell compartment. Tpo is a heavily glycosylated, hepatocyte-derived cytokine which functions by binding to its receptor (TpoR) on target cells and thereby activating intracellular signalling cascades that induce their proliferation and/or differentiation. In addition to its role in signal propagation, TpoR is expressed on the surface of platelets, where it contributes to regulation of Tpo levels by sequestering circulating cytokine. TpoR belongs to the homodimeric Class I cytokine receptor family but is unusual due to a duplication of the Cytokine binding Homology Region (CHR). Almost thirty years after initial discovery of TpoR, the structure of the human Tpo:TpoR interaction was recently reported. Here we determine the structure of extracellular portion of the murine Tpo:TpoR signalling complex using single particle cryo-EM. The structure reveals that Tpo:TpoR forms a largely symmetrical 1:2 complex. The cytokine cross-links the same site on the membrane-distal CHR of both receptor chains using opposing surfaces and with significantly different affinities. This orients the two membrane-proximal CHRs such that they contact one another adjacent to the plasma membrane. The potential cytokine-binding site in CHR2 is glycosylated and does not interact with Tpo. A large insertion in CHR1 that is unique to Tpo forms a partially structured loop that is disulphide bonded to CHR2 and, in one receptor chain, contacts cytokine. Biochemical analyses indicate that the glycosylated C-terminal domain of Tpo does not influence receptor binding. We demonstrate that the therapeutic TpoR agonist Romiplostim binds to the same site on the receptor as does cytokine. Our study characterises the Tpo/TpoR interaction structurally and biochemically to allow for the future development of potent TpoR agonists for therapeutic use.
Project description:Protein glycosylation is increasingly recognized as a common protein modification across bacterial species. Within members of the Neisseria genus O-linked protein glycosylation plays important roles in virulence and antigenic variation yet our understanding of the substrates of glycosylation are limited. Recently it was identified that even closely related Neisserial species can possess O-oligosaccharyltransferases, pglOs, that possess varying glycosylation specificities suggesting that distinct targeting activities may impact both the glycoprotome as well as the proteome of Neisserial species. Within this work we explore this concept using of Field Asymmetric Waveform Ion Mobility Spectrometry (FAIMS) fractionation and Data-Independent Acquisition (DIA) to allow the characterization of differences in the glycoproteomes and proteomes within N. gonorrhoeae strains expressing differing pglO alleles. We demonstrate the utility of FAIMS to expand the known glycoproteome of N. gonorrhoeae and enable comparative glycoproteomics of a recently reported panel of N. gonorrhoeae strains expressing different pglO allelic chimeras (15 pglO enzymes) with unique substrate targeting activities. Combining glycoproteomic insights with DIA proteomics we demonstrate that alterations within pglO alleles have widespread impacts on the proteome of N. gonorrhoeae yet lead to minimal effects on the abundance of glycoproteins. Additionally, while DIA analysis can allow occupancy to be inferred by the absence or presence of peptides known to be modified, we observe a poor correlation between DIA measurements of non-modified versions of glycopeptides and glycoproteomic analysis. Combined this work expands our understanding of the N. gonorrhoeae glycoproteome and supports that the expression of different pglO alleles appears to drive proteomic changes independent of the glycoproteins targeted for glycosylation.
Project description:Protein glycosylation is increasingly recognized as a common protein modification across bacterial species. Within members of the Neisseria genus O-linked protein glycosylation plays important roles in virulence and antigenic variation yet our understanding of the substrates of glycosylation are limited. Recently it was identified that even closely related Neisserial species can possess O-oligosaccharyltransferases, pglOs, that possess varying glycosylation specificities suggesting that distinct targeting activities may impact both the glycoprotome as well as the proteome of Neisserial species. Within this work we explore this concept using of Field Asymmetric Waveform Ion Mobility Spectrometry (FAIMS) fractionation and Data-Independent Acquisition (DIA) to allow the characterization of differences in the glycoproteomes and proteomes within N. gonorrhoeae strains expressing differing pglO alleles. We demonstrate the utility of FAIMS to expand the known glycoproteome of N. gonorrhoeae and enable comparative glycoproteomics of a recently reported panel of N. gonorrhoeae strains expressing different pglO allelic chimeras (15 pglO enzymes) with unique substrate targeting activities. Combining glycoproteomic insights with DIA proteomics we demonstrate that alterations within pglO alleles have widespread impacts on the proteome of N. gonorrhoeae yet lead to minimal effects on the abundance of glycoproteins. Additionally, while DIA analysis can allow occupancy to be inferred by the absence or presence of peptides known to be modified, we observe a poor correlation between DIA measurements of non-modified versions of glycopeptides and glycoproteomic analysis. Combined this work expands our understanding of the N. gonorrhoeae glycoproteome and supports that the expression of different pglO alleles appears to drive proteomic changes independent of the glycoproteins targeted for glycosylation.
Project description:Protein glycosylation is increasingly recognized as a common protein modification across bacterial species. Within pathogenic members of the Neisseria genus O-linked protein glycosylation is associated with virulence yet the depth of the glycoproteome, or if glycosylation plays additional roles in Neisserial physiology are largely unknown. Recently it was identified that even closely related members of the Neisseria genus can possess O-Oligosaccharyltransferases, pglOs, that possess distinct targeting activities suggesting extensive glycoproteome diversity in terms of the substrates capable of being glycosylated across Neisserial species. Within this work we explore this concept using Field Asymmetric Waveform Ion Mobility Spectrometry (FAIMS) fractionation and Data-Independent Acquisition (DIA) to allow the characterization of differences in the glycoproteomes and proteomes within N. gonorrhoeae strains expressing differing pglO alleles. We demonstrate the utility of FAIMS to expand the known glycoproteome of N. gonorrhoeae enabling the characterization of the glycoproteomes of wild type N. gonorrhoeae MS11 as well as a recently reported panel of strains expressing different pglO allelic chimeras (15 PglO enzymes) with unique substrate targeting activities. Combining glycoproteomic insights with DIA proteomics we demonstrate that alterations within pglO alleles have widespread impacts on the proteome of N. gonorrhoeae. Examination of peptides known to be targeted by glycosylation using DIA analysis supports alterations in glycosylation occupancy independent of changes in protein levels and that the occupancy of glycosylation is generally low on most glycoproteins. Combined this work expands our understanding of the N. gonorrhoeae glycoproteome and the impact of glycosylation on bacterial species.
Project description:The trypanosomatid protozoan parasite Leishmania has a significant impact on human health globally. Understanding the pathways associated with virulence within this significant pathogen is critical for identifying novel vaccination and chemotherapy targets. Within this study we leverage an ultradeep proteomic approach to improve our understanding of two virulence associated genes in Leishmania; the Golgi Mannose/Arabinopyranose/Fucose nucleotide-sugar transporter LPG2, and the mitochondrial fucosyltransferase FUT1. Using deep peptide fractionation followed by complementary fragmentation approaches with higher energy collisional dissociation (HCD) and Electron-transfer dissociation (ETD) allowed the identification of over 6500 proteins, nearly doubling the experimentally observed Leishmania major proteome. This deep proteomic analysis revealed significant quantitative differences in both lpg2- and fut1s mutants with FUT1-dependent changes linked to marked alterations within mitochondrial associated proteins while LPG2-dependent changes impacted multiple aspects of the secretory pathway. While FUT1 has been shown to fucosylate peptides in vitro, no evidence for protein fucosylation was identified within our ultradeep analysis nor did we observe fucosylated glycans within Leishmania glycopeptides isolated using HILIC enrichment. Combined this work provides a critical proteomic resource for the community on the observable Leishmania proteome as well as highlights phenotypic changes associated with LPG2/FUT1 which may guide the development of future therapeutics.
Project description:Levoglucosan is produced in the pyrolysis of cellulose and starch, including from bushfires or the burning of biofuels, and is deposited from the atmosphere across the surface of the earth. We describe two levoglucosan degrading Paenarthrobacter spp. (Paenarthrobacter nitrojuajacolis LG01 and Paenarthrobacter histidinolovorans LG02) that were isolated by metabolic enrichment on levoglucosan as sole carbon source. Genome sequencing and proteomics analysis revealed expression of a series of gene clusters encoding known levoglucosan degrading enzymes, levoglucosan dehydrogenase (LGDH, LgdA), 3-keto-levoglucosan b-eliminase (LgdB1) and glucose 3-dehydrogenase (LgdC), along with an ABC transporter cassette and associated solute binding protein. However, no homologues of 3-ketoglucose dehydratase (LgdB2) were evident. The expressed gene clusters contained a range of putative sugar phosphate isomerase/xylose isomerases with weak similarity to LgdB2. Sequence similarity network analysis of genome neighbors revealed that homologues of LgdA, LgdB1 and LgdC are generally conserved in a range of bacteria in the phyla Firmicutes, Actinobacteria and Proteobacteria. One sugar phosphate isomerase/xylose isomerase cluster (LgdB3) was identified with limited distribution mutually exclusive with LgdB2. LgdB1, LgdB2 and LgdB3 adopt similar predicted 3D folds suggesting overlapping function in processing intermediates in LG metabolism. Our findings highlight the diversity within the LGDH pathway through which bacteria utilize levoglucosan as a nutrient source.
Project description:Within the Burkholderia genus O-linked protein glycosylation is now known to be highly conserved at the pathway and glycosylation substrate levels. While inhibition of glycosylation has been shown to be detrimental to virulence in B. cenocepacia, little is known about the role of glycosylation in Burkholderia glycoproteins. Within this study we have sought to improve our understanding of the breadth and dynamics of the B. cenocepacia O-glycoproteome to identify glycoproteins which require glycosylation for functionality. Assessing the glycoproteome across multiple common culturing media (LB, TSB, and artificial sputum medium to simulate cystic fibrosis sputum-like conditions) we demonstrate at least 141 glycoproteins are subjected to glycosylation within B. cenocepacia K56-2. Leveraging this insight, we quantitively assessed the glycoproteome of B. cenocepacia using Data-Independent Acquisition (DIA) across culturing media and growth phases revealing most B. cenocepacia glycoproteins are express under all conditions. Examination of how the absence of glycosylation impacts the glycoproteome reveals only a subset of the glycoproteome (BCAL1086, BCAL2974, BCAL0525, BCAM0505 and BCAL0127) appear impacted by the loss of glycosylation. Assessing the proteomic and phenotypic impacts of the loss of these glycoproteins compared to glycosylation null strains revealing the loss of BCAL0525, and to a lesser extend BCAL0127, mirror the proteomic effects observed in the absence of glycosylation. Finally, we demonstrate the loss of glycosylation within BCAL0525 at Serine-358 results in both loss of motility and proteomic impacts on flagellar apparatus consistent with the loss of apparatus stability. Combined this work demonstrates that O-linked glycosylation of BCAL0525 is functionally important within B. cenocepacia.