scholarly journals Ubiquitination of the yeast receptor Atg32 modulates mitophagy

2019 ◽  
Author(s):  
Pierre Vigié ◽  
Cécile Gonzalez ◽  
Stephen Manon ◽  
Ingrid Bhatia-Kissova ◽  
Nadine Camougrand
Keyword(s):  
Mass Spectrometry ◽  
Quality Control ◽  
Stationary Phase ◽  
Proteolytic Activity ◽  
Posttranslational Modifications ◽  
Protein Level ◽  
Mitochondrial Membrane ◽  
Mass Spectrometry Analysis ◽  
Outer Mitochondrial Membrane ◽  
Spectrometry Analysis

AbstractMitophagy, the process that degrades mitochondria selectively through autophagy, is involved in the quality control of these organelles. In yeast, the presence of the Atg32 protein on the outer mitochondrial membrane allows for the recognition and targeting of superfluous or damaged mitochondria for degradation. Some posttranslational modifications, such as phosphorylation, are crucial for the execution of the mitophagy process. In our study, we showed that in the stationary phase of growth, and to a lesser extent during starvation, the Atg32 protein level decreases. The fact that a decline in Atg32 level can be prevented by inhibition of the proteolytic activity of proteasome may indicate that Atg32 is also ubiquitylated. In fact, mass spectrometry analysis of purified Atg32 protein showed ubiquitination of lysine residue in position 282. These different patterns of posttranslational modifications of Atg32 could allow cells to control the mitophagy process carefully.

scholarly journals ProbingN-glycoprotein microheterogeneity by lectin affinity purification-mass spectrometry analysis

2019 ◽  
Vol 10 (19) ◽  
pp. 5146-5155 ◽  
Author(s):  
Di Wu ◽  
Jingwen Li ◽  
Weston B. Struwe ◽  
Carol V. Robinson
Keyword(s):  
Mass Spectrometry ◽  
Protein Level ◽  
Affinity Purification ◽  
Mass Spectrometry Analysis ◽  
Intact Protein ◽  
Spectrometry Analysis ◽  
Lectin Affinity ◽  
Affinity Purification Mass Spectrometry

A lectin affinity purification-mass spectrometry approach to characterize lectin-reactive glycoproteoforms and elucidate lectin specificities at the intact protein level.

scholarly journals Primary Structure and Antibacterial Activity of Chicken Bone Marrow-Derived β-Defensins

2009 ◽  
Vol 53 (11) ◽  
pp. 4647-4655 ◽  
Author(s):  
Chrystelle Derache ◽  
Valérie Labas ◽  
Vincent Aucagne ◽  
Hervé Meudal ◽  
Céline Landon ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Bone Marrow ◽  
Posttranslational Modifications ◽  
Amino Acid Sequences ◽  
Biologically Active ◽  
Mass Spectrometry Analysis ◽  
Gram Positive ◽  
Intact Cells ◽  
Spectrometry Analysis ◽  
Chicken Bone

ABSTRACTThree biologically active β-defensins were purified by chromatography from chicken bone marrow extract: avian β-defensin 1 (AvBD1), AvBD2, and the newly isolated β-defensin AvBD7. Mass spectrometry analyses showed that bone marrow-derived AvBD1, -2, and -7 peptides were present as mature peptides and revealed posttranslational modifications for AvBD1 and AvBD7 in comparison to their in silico-predicted amino acid sequences. Tandem mass spectrometry analysis using the nanoelectrospray-quadrupole time of flight method showed N-terminal glutaminyl cyclization of mature AvBD7 and C-terminal amidation of mature AvBD1 peptide, while posttranslational modifications were absent in bone marrow-derived mature AvBD2 peptide. Furthermore, mass spectrometry analysis performed on intact cells confirmed the presence of these three peptides in mature heterophils. In addition, the antibacterial activities of the three β-defensins against a large panel of gram-positive and -negative bacteria were assessed. While the three defensins displayed similar antibacterial spectra of activity against gram-positive strains, AvBD1 and AvBD7 exhibited the strongest activity against gram-negative strains in comparison to AvBD2.

Acoustic Ejection/Full-Scan Mass Spectrometry Analysis for High-Throughput Compound Quality Control

2020 ◽  
pp. 247263032096762
Author(s):  
Jun Zhang ◽  
Yong Zhang ◽  
Chang Liu ◽  
Tom Covey ◽  
Julia Nielsen ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Quality Control ◽  
Data Processing ◽  
High Throughput ◽  
Data Extraction ◽  
Mass Spectrometry Analysis ◽  
High Throughput Analysis ◽  
Spectrometry Analysis ◽  
Microtiter Plates ◽  
Full Scan

High-throughput analysis of compound dissolved in DMSO and arrayed in multiwell plates for quality control (QC) purposes has widespread utility in drug discovery, ranging from the QC of assay-ready plates dispatched by compound management, to compound integrity check in the screening collection, to reaction monitoring of chemical syntheses in microtiter plates. Due to the large number of samples (thousands per batch) involved, these workflows can put a significant burden on the liquid chromatography–mass spectrometry (LC-MS) platform typically used. To achieve the required speed of seconds per sample, several chromatography-free MS approaches have previously been used with mixed results. In this study, we demonstrated the feasibility of acoustic ejection–mass spectrometry (AE-MS) in full-scan mode for high-throughput compound QC in miniaturized formats, featuring direct, contactless liquid sampling, minimal sample consumption, and ultrafast analytical speed. The sample consumption and analysis time by AE-MS represent, respectively, a 1000-fold and 30-fold reduction compared with LC-MS. In qualitative QC, AE-MS generated comparable results to conventional LC-MS in identifying the presence and absence of expected compounds. AE-MS also demonstrated its utility in relative quantifications of the same compound in serial dilution plates, or substrate in chemical synthesis. To facilitate the processing of a large amount of data generated by AE-MS, we have developed a data processing platform using commercially available tools. The platform demonstrated fast and straightforward data extraction, reviewing, and reporting, thus eliminating the need for the development of custom data processing tools. The overall AE-MS workflow has effectively eliminated the analytical bottleneck in the high-throughput compound QC work stream.

scholarly journals The yeast mitophagy receptor Atg32 is ubiquitinated and degraded by the proteasome

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0241576
Author(s):  
Nadine Camougrand ◽  
Pierre Vigié ◽  
Cécile Gonzalez ◽  
Stéphen Manon ◽  
Ingrid Bhatia-Kiššová
Keyword(s):  
Mitochondrial Membrane ◽  
Normal Growth ◽  
Growth Conditions ◽  
Mass Spectrometry Analysis ◽  
Outer Mitochondrial Membrane ◽  
Post Translational Modifications ◽  
Spectrometry Analysis ◽  
Lysine Residues ◽  
The Stability ◽  
Respiratory Conditions

Mitophagy, the process that degrades mitochondria selectively through autophagy, is involved in the quality control of mitochondria in cells grown under respiratory conditions. In yeast, the presence of the Atg32 protein on the outer mitochondrial membrane allows for the recognition and targeting of superfluous or damaged mitochondria for degradation. Post-translational modifications such as phosphorylation are crucial for the execution of mitophagy. In our study we monitor the stability of Atg32 protein in the yeast S. cerevisiae and show that Atg32 is degraded under normal growth conditions, upon starvation or rapamycin treatment. The Atg32 turnover can be prevented by inhibition of the proteasome activity, suggesting that Atg32 is also ubiquitinated. Mass spectrometry analysis of purified Atg32 protein revealed that at least lysine residue in position 282 is ubiquitinated. Interestingly, the replacement of lysine 282 with alanine impaired Atg32 degradation only partially in the course of cell growth, suggesting that additional lysine residues on Atg32 might also be ubiquitinated. Our results provide the foundation to further elucidate the physiological significance of Atg32 turnover and the interplay between mitophagy and the proteasome.

scholarly journals Combinatorial native MS and LC-MS/MS approach reveals high intrinsic phosphorylation of human Tau but minimal levels of other key modifications

2020 ◽  
Author(s):  
Friedel Drepper ◽  
Jacek Biernat ◽  
Senthillvelrajan Kaniyappan ◽  
Helmut E. Meyer ◽  
Eva Maria Mandelkow ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Posttranslational Modifications ◽  
Native Mass Spectrometry ◽  
Eukaryotic Cell ◽  
Cell System ◽  
Mass Spectrometry Analysis ◽  
Phosphorylation Sites ◽  
Spectrometry Analysis ◽  
Phosphorylated Peptides ◽  
Tau Aggregation

AbstractAbnormal changes in the neuronal microtubule-associated protein Tau, such as hyperphosphorylation and aggregation, are considered hallmarks of cognitive deficits in Alzheimer disease. Hyperphosphorylation is thought to take place before aggregation, and therefore it is often assumed that phosphorylation predisposes Tau towards aggregation. However, the nature and extent of phosphorylation has remained ill-defined. Tau protein contains up to 85 potential phosphorylation sites (80 Ser/Thr, and 5 Tyr P-sites), many of which can be phosphorylated by various kinases because the unfolded structure of Tau makes them accessible. However, limitations in methods (e.g. in mass spectrometry of phosphorylated peptides, or antibodies against phospho-epitopes) have led to conflicting results regarding the overall degree of phosphorylation of Tau in cells. Here we present results from a new approach, that is based on native mass spectrometry analysis of intact Tau expressed in a eukaryotic cell system (Sf9) which reveals Tau in different phosphorylation states. The extent of phosphorylation is remarkably heterogeneous with up to ∼20 phosphates (Pi) per molecule and distributed over 51 sites (including all P-sites published so far and additional 18 P-sites). The medium phosphorylated fraction Pm showed overall occupancies centered at 8 Pi (± 5 Pi) with a bell-shaped distribution, the highly phosphorylated fraction Ph had 14 Pi (± 6 Pi). The distribution of sites was remarkably asymmetric (with 71% of all P-sites located in the C-terminal half of Tau). All phosphorylation sites were on Ser or Thr residues, but none on Tyr. Other known posttranslational modifications of Tau were near or below our detection limit (e.g. acetylation, ubiquitination). None of the Tau fractions self-assemble readily, arguing that Tau aggregation is not promoted by phosphorylation per se but requires additional factors.

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