ABSTRACT: by using a mass spectrometry-based quantitative proteomics approach, we discovered that OCTR-1 regulates innate immunity by suppressing translation and the unfolded protein response (UPR) pathways at the protein level.
Upon pathogen infection, microbial killing pathways and cellular stress pathways are rapidly activated by the host innate immune system. These pathways must be tightly regulated because insufficient or excessive immune responses have deleterious consequences. Increasing evidence indicates that the nervous system regulates the immune system to confer coordinated protection to the host. However, the precise mechanisms of neural-immune communication remain unclear. Previously we have demonstrated t ...[more]
Project description:Peptide fragmentation spectra are routinely predicted in the interpretation of mass spectrometry-based proteomics data. Unfortunately, the generation of fragment ions is not well enough understood to estimate fragment ion intensities accurately. Here, we demonstrate that machine learning can predict peptide fragmentation patterns in mass spectrometers with accuracy within the uncertainty of the measurements. Moreover, analysis of our models reveals that peptide fragmentation depends on long-range interactions within a peptide sequence. We illustrate the utility of our models by applying them to the analysis of both data-dependent and data-independent acquisition datasets. In the former case, we observe a significant increase in the total number of peptide identifications at fixed false discovery rate. In the latter case we demonstrate that the use of predicted MS/MS spectra is equivalent to the use of spectra from experimentallibraries, indicating that fragmentation libraries for proteomics are becoming obsolete.
Project description:Protein phosphorylation is vital for the regulation of cellular signaling. Isobaric tag-based proteomic techniques, such as tandem mass tags (TMT), can measure the relative phosphorylation states of peptides in a multiplexed format. However, the overall low stoichiometry of protein phosphorylation constrains the analytical depth of phosphopeptide analysis by mass spectrometry, thereby requiring robust and sensitive workflows. Here we evaluate and optimize high-Field Asymmetric waveform Ion Mobility Spectrometry (FAIMS) coupled to Orbitrap Tribrid mass spectrometers for the analysis of TMT10plex-labeled phosphopeptides. We determined that using FAIMS-SPS-MS3 with three compensation voltages (CV) in a single method minimizes inter-CV overlap and maximizes peptide coverage (e.g., CV=-40V/-60V/-80V) and that consecutive analyses using CID-MSA and HCD fragmentation at the MS2 stage increases the depth of phosphorylation analysis.
Project description:To better elucidate the mechanisms of calcium-mediated germination of soybean seed, morphological analysis was performed in seed imbibed with different concentrations of CaCl2. Based on morphological results, radicle of germinating seed imbibed with 5 and 50 mM CaCl2 was collected for proteomic analysis.
Project description:Native intact N-glycopeptides analysis can access to a lot of useful information including N-glycosites, N-glycans and N-glycoproteins of original complex samples. The traditional sample preprocessing method is to analyze the tryptic intact N-glycopeptides enriched using hydrophilic materials or some new materials by LC-MS/MS. However, the number of identified intact N-glycopeptides was very limited using existing methods. Herein, we systematically compared the different analytical methods, including the use of different sources of trypsin, combinations of different proteases and different enrichment materials.
Project description:N-glycoproteins are involved in various biological processes. Certain distinctive glycoforms on specific glycoproteins enhance the specificity and/or sensitivity of cancer diagnosis. Therefore, the characterization of plasma N-glycoproteome is essential for new biomarker discovery. Absence of suitable analytical methods for in-depth and large-scale analyses of low-abundance plasma glycoproteins make it challenging to investigate the role of glycosylation. In this study, we developed an integrated method termed Glyco-CPLL, which integrates combinatorial peptide ligand libraries, high-pH reversed-phase pre-fractionation, hydrophilic interaction chromatography, trypsin and PNGase F digestion, shotgun proteomics, and various analysis software (MaxQuant and pGlyco2.0) for the low-abundance plasma glycoproteomic profiling. Then, we utilized the method to perform a comparative study and to explore papillary thyroid carcinoma-related proteins and glycosylations with reference to healthy controls. Finally, a large and comprehensive human plasma N-glycoproteomic database was established, containing 786 proteins, 369 N-glycoproteins, 862 glycosites, 171 glycan compositions, and 1644 unique intact N-glycopeptides. Additionally, several low-abundance plasma glycoproteins were identified, including SVEP1 (~0.54 ng/mL), F8 (~0.83 ng/mL), ADAMTS13 (~1.2 ng/mL). These results suggest that this method will be useful for analyzing plasma intact glycopeptides in future studies. Besides, the Glyco-CPLL method has a great potential to be translated to clinical applications.
Project description:DNA damage causes cancer, impairs development and accelerates aging. UV irradiation induces transcription-blocking lesions and defects in transcription-coupled nucleotide excision repair lead to developmental failure and premature aging in humans. Following DNA repair, the homeostatic processes need to be reestablished to ensure development and maintain tissue functionality. Here, we report that in C. elegans removal of the MLL/COMPASS H3K4 methyltransferase exacerbates the developmental growth retardation and accelerates aging, while depletion of the H3K4 demethylase, SPR-5, promotes developmental growth and extends lifespan amid UV-induced damage. We demonstrate that specifically the DDR-induced H3K4me2 is associated with the activation of genes regulating RNA transport, splicing, ribosome biogenesis, and protein homeostasis and regulates the recovery of protein biosynthesis that is essential for survival of UV-induced DNA damage. Our study uncovers a role of H3K4me2 in coordinating the recovery of protein biosynthesis and homeostasis that is required for developmental growth and longevity after DNA damage.
Project description:Cell cycle transitions are generally triggered by variation in the activity of cyclin-dependent kinases (CDKs) bound to cyclins. Malaria-causing parasites have a life cycle with unique cell-division cycles, and a repertoire of divergent CDKs and cyclins of poorly understood function and interdependency. We show that Plasmodium berghei CDK-related kinase 5 (CRK5), is a critical regulator of atypical mitosis in the gametogony and is required for mosquito transmission. It phosphorylates canonical CDK motifs of components in the pre-replicative complex and is essential for DNA replication. We also provide evidence for indirect regulation of the concomitant M-phase progression. During a replicative cycle, CRK5 stably interacts with a single Plasmodium-specific cyclin (SOC2), although we obtained no evidence of SOC2 cycling by transcription, translation or degradation. Our results provide evidence that during Plasmodium male gametogony, this unique cyclin/CDK pair fills the functional space of multiple eukaryotic cell-cycle kinases controlling DNA replication and M-phase progression.
Project description:We further expanded on previous optimizations to isolate the plasma peptidome and compared various methods to maximize identifications with speed and ease. Previous studies have reported loss of polypeptides binding to high abundant proteins during depletion strategies. We hypothesized that rapid chaotropic denaturation of plasma with urea under reducing conditions would liberate non-covalently bound peptides to improve recovery during protein depletion. We also compared depletion strategies to isolate the peptidome including protein precipitation and removal with either TCA, acetone or acetonitrile (AcN). Following centrifugation of precipitated proteins, the supernatant containing peptides was collected. For acetone and AcN precipitations, an additional vacuum centrifugation step was required followed by resuspension of peptides in aqueous buffer. Our comparison of peptidome isolation also included removal of proteins with size-exclusion 10 kDa MWCO filters. All peptide isolations were acidified to 0.1% TFA, adjusted to 5% acetonitrile and desalted with HLB-SPE. Peptides were analysed by single-shot nanoUHPLC-MS/MS employing both HCD and EThcD and quantified by LFQ
Project description:Genes clustered into polycistronic operons was thought a characteristic of bacteria and many other species. More than half protein-coding genes are organized in polycistronic operons composed of two or more than ten genes in bacterial genomes. Although the structure of operons have been studied precisely, how the member genes within operon maintain their stoichiometry expression is remain unknown. Using a highly accurate label-free absolute quantification method DIA (data-independent acquisition), we present a global analysis of Escherichia coli proteome, quantified 1607 proteins, including 59.1% of the known polycistronic operons. We found shorter operons tend to be more tightly controlled than longer operons, and those operons for metabolic pathways are less controlled for stoichiometry balance than those operons for protein complexes. Our results thus reveal the two-level regulation mode involving transcription and translation of operons would balance the stoichiometry expression of genes in polycistronic operons in different time-scale.