Biology subjects

Silbern, I.

Publications and source records attributed to Silbern, I..

3 recordsLinked to original sources

bioRxiv2021

Evaluation and Optimization of High-Field Asymmetric Waveform Ion Mobility Spectrometry for Multiplexed Quantitative Site-specific N-glycoproteomics

The heterogeneity and complexity of glycosylation hinder the depth of site-specific glycoproteomics analysis. High-field asymmetric-waveform ion-mobility spectrometry (FAIMS) has shown to improve the scope of bottom-up proteomics. The benefits of FAIMS for quantitative N-glycoproteomics have not been investigated yet. In this work, we optimized FAIMS settings for N-glycopeptide identification, with or without the tandem mass tag (TMT) label. The optimized FAIMS approach significantly increased the identification of site-specific N-glycopeptides derived from the purified IgM protein or human lymphoma cells. We explored in detail the changes in FAIMS mobility caused by N-glycopeptides with different characteristics, including TMT labeling, charge state, glycan type, peptide sequence, glycan size and precursor m/z. Importantly, FAIMS also improved multiplexed N-glycopeptide quantification, both with the standard MS2 acquisition method and with our recently developed Glyco-SPS-MS3 method. The combination of FAIMS and Glyco-SPS-MS3 provided the highest quantitative accuracy and precision. Our results demonstrate the advantages of FAIMS for improved mass-spectrometry-based qualitative and quantitative N-glycoproteomics. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=75 SRC="FIGDIR/small/436434v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@126b92forg.highwire.dtl.DTLVardef@147d6e5org.highwire.dtl.DTLVardef@16d6eb0org.highwire.dtl.DTLVardef@17dfe2a_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2020

Post-Translational Modifications Soften Intermediate Filaments

The mechanical properties of biological cells are determined by the cytoskeleton, a composite biopolymer network consisting of microtubules, actin filaments and intermediate filaments (IFs). By differential expression of cytoskeletal proteins, modulation of the network architecture and interactions between the filaments, cell mechanics may be adapted to varying requirements on the cell. Here, we focus on the intermediate filament protein vimentin and introduce post-translational modifications as an additional, much faster mechanism for mechanical modulation. We study the impact of phosphorylation on filament mechanics by recording force-strain curves using optical traps. Partial phosphorylation softens the filaments. We show that binding of the protein 14-3-3 to phosphorylated vimentin IFs further enhances this effect and speculate that in the cell 14-3-3 may serve to preserve the softening and thereby the altered cell mechanics. We explain our observation by the additional charges introduced during phosphorylation.

biophysics↗

bioRxiv2020

SugarQuant: a streamlined pipeline for multiplexed quantitative site-specific N-glycoproteomics

Site-specific regulation of protein N-glycosylation is essential in human cells. However, accurate quantification of glycosylation sites and their individual glycan moieties in a cell-wide manner is still technically challenging. Here, we introduce SugarQuant, an integrated mass spectrometry-based pipeline comprising fast protein aggregation capture (PAC)-based sample preparation, optimized multi-notch MS3 LC-MS acquisition (Glyco-SPS-MS3) and a data-processing tool (GlycoBinder) that allows for confident, global identification and quantification of intact glycopeptides in complex biological samples. PAC greatly reduces the overall samplehandling time without compromising sensitivity. Glyco-SPS-MS3 combines high-resolution MS2 and MS3 scans, resulting in enhanced reporter signals of isobaric mass tags, improved detection of N-glycopeptide fragments, and significantly lowered interference in multiplexed quantification. GlycoBinder enables streamlined processing of Glyco-SPS-MS3 data, followed by a two-step database search which increases the identification rates of intact glycopeptides by up to 22% when compared with one-step database search strategies. SugarQuant was applied to identify and quantify more than 5,000 unique glycoforms in Burkitts lymphoma cells, and determined complex site-specific glycosylation changes that occurred upon inhibition of fucosylation at high confidence.

biochemistry↗