Observation ofEscherichia coliRibosomal Proteins and Their Posttranslational Modifications by Mass Spectrometry

1999 ◽  
Vol 269 (1) ◽  
pp. 105-112 ◽  
Author(s):  
Randy J. Arnold ◽  
James P. Reilly
Keyword(s):  
Mass Spectrometry ◽  
Posttranslational Modifications

scholarly journals Characterization of posttranslational modifications in neuron-specific class III beta-tubulin by mass spectrometry.

1991 ◽  
Vol 88 (11) ◽  
pp. 4685-4689 ◽  
Author(s):  
J. E. Alexander ◽  
D. F. Hunt ◽  
M. K. Lee ◽  
J. Shabanowitz ◽  
H. Michel ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Posttranslational Modifications ◽  
Specific Class ◽  
Class Iii ◽  
Beta Tubulin

scholarly journals Posttranslational Modifications of Baculovirus Protamine-Like Protein P6.9 and the Significance of Its Hyperphosphorylation for Viral Very Late Gene Hyperexpression

2015 ◽  
Vol 89 (15) ◽  
pp. 7646-7659 ◽  
Author(s):  
Ao Li ◽  
Haizhou Zhao ◽  
Qingying Lai ◽  
Zhihong Huang ◽  
Meijin Yuan ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Posttranslational Modifications ◽  
Deletion Mutant ◽  
Viral Gene ◽  
Sf9 Cells ◽  
Viral Infectivity ◽  
Serine Threonine Kinase ◽  
Threonine Kinase ◽  
Viral Gene Transcription ◽  
Late Genes

ABSTRACTMany viruses utilize viral or cellular chromatin machinery for efficient infection. Baculoviruses encode a conserved protamine-like protein, P6.9. This protein plays essential roles in various viral physiological processes during infection. However, the mechanism by which P6.9 regulates transcription remains unknown. In this study, 7 phosphorylated species of P6.9 were resolved in Sf9 cells infected with the baculovirus type speciesAutographa californicamultiple nucleopolyhedrovirus (AcMNPV). Mass spectrometry identified 22 phosphorylation and 10 methylation sites but no acetylation sites in P6.9. Immunofluorescence demonstrated that the P6.9 and virus-encoded serine/threonine kinase PK1 exhibited similar distribution patterns in infected cells, and coimmunoprecipitation confirmed the interaction between them. Uponpk1deletion, nucleocapsid assembly and polyhedron formation were interrupted and the transcription of viral very late genes was downregulated. Interestingly, we found that the 3 most phosphorylated P6.9 species vanished from Sf9 cells transfected with thepk1deletion mutant, suggesting that PK1 is involved in the hyperphosphorylation of P6.9. Mass spectrometry suggested that the phosphorylation of the 7 Ser/Thr and 5 Arg residues in P6.9 was PK1 dependent. Replacement of the 7 Ser/Thr residues with Ala resulted in a P6.9 phosphorylation pattern similar to that of thepk1deletion mutant. Importantly, the decreases in the transcription level of viral very late genes and viral infectivity were consistent. Our findings reveal that P6.9 hyperphosphorylation is a precondition for the maximal hyperexpression of baculovirus very late genes and provide the first experimental insights into the function of the baculovirus protamine-like protein and the related protein kinase in epigenetics.IMPORTANCEDiverse posttranslational modifications (PTMs) of histones constitute a code that creates binding platforms that recruit transcription factors to regulate gene expression. Many viruses also utilize host- or virus-induced chromatin machinery to promote efficient infections. Baculoviruses encode a protamine-like protein, P6.9, which is required for a variety of processes in the infection cycle. Currently, P6.9's PTM sites and its regulating factors remain unknown. Here, we found that P6.9 could be categorized as unphosphorylated, hypophosphorylated, and hyperphosphorylated species and that a virus-encoded serine/threonine kinase, PK1, was essential for P6.9 hyperphosphorylation. Abundant PTM sites on P6.9 were identified, among which 7 Ser/Thr phosphorylated sites were PK1 dependent. Mutation of these Ser/Thr sites reduced very late viral gene transcription and viral infectivity, indicating that the PK1-mediated P6.9 hyperphosphorylation contributes to viral proliferation. These data suggest that a code exists in the sophisticated PTM of viral protamine-like proteins and participates in viral gene transcription.

scholarly journals The Plant PTM Viewer, a central resource exploring plant protein modifications. From site-seeing to protein function

2018 ◽  
Author(s):  
Patrick Willems ◽  
Alison Horne ◽  
Sofie Goormachtig ◽  
Ive De Smet ◽  
Alexander Botzki ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Posttranslational Modifications ◽  
Protein Function ◽  
Protein Sequences ◽  
Specific Protein ◽  
Specific Information ◽  
Active Site Residues ◽  
Functional Protein ◽  
Protein Modifications ◽  
Modern Mass

SUMMARYPosttranslational modifications (PTMs) of proteins are central in any kind of cellular signaling. Modern mass spectrometry technologies enable comprehensive identification and quantification of various PTMs. Given the increased number and types of mapped protein modifications, a database is necessary that simultaneouly integrates and compares site-specific information for different PTMs, especially in plants for which the available PTM data are poorly catalogued. Here, we present the Plant PTM Viewer (http://www.psb.ugent.be/PlantPTMViewer), an integrative PTM resource that comprises approximately 200,000 PTM sites for 17 types of protein modifications in plant proteins from five different species. The Plant PTM Viewer provides the user with a protein sequence overview in which the experimentally evidenced PTMs are highlighted together with functional protein domains or active site residues. The PTM sequence search tool can query PTM combinations in specific protein sequences, whereas the PTM BLAST tool searches for modified protein sequences to detect conserved PTMs in homologous sequences. Taken together, these tools facilitate to assume the role and potential interplay of PTMs in specific proteins or within a broader systems biology context. The Plant PTM Viewer is an open repository that allows submission of mass spectrometry-based PTM data to remain at pace with future PTM plant studies.

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.

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