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@#Objective To explore the factors affecting the stability of high concentration variable domain of heavy-chain antibody-Fc(VHH-Fc) fusion protein.Methods Three groups of forced degradation experiments,shaking,light and 40℃ high temperature were set up.Differential scanning fluorimetry,dynamic light scattering(DLS) and ultra performance liquid chromatography-mass spectrometry(UPLC-MS) were used to detect the effects of the three forced degradation conditions on the conformational stability,colloidal stability,average hydrodynamic diameter and post-translational modifications of high concentration VHH-Fc fusion protein.Results Under the light condition,the onset temperature of unfolding(T_(onset)),melting temperature(T_m) and aggregation onset temperature(T_(agg)) of high concentration VHH-Fc fusion protein decreased the most,and the oxidation ratio of Met160 and Met266 increased significantly.Under the condition of shaking,the variation of the diffusion interaction parameter(k_D) and the average hydrodynamic diameter was the largest.Conclusion Light can significantly reduce the conformational stability of high concentration VHH-Fc fusion protein and induce methionine oxidation.Shaking has the most significant effect on its colloidal stability and promotes aggregation.
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Metabolic reprogramming is a hallmark of cancer, including lung cancer. However, the exact underlying mechanism and therapeutic potential are largely unknown. Here we report that protein arginine methyltransferase 6 (PRMT6) is highly expressed in lung cancer and is required for cell metabolism, tumorigenicity, and cisplatin response of lung cancer. PRMT6 regulated the oxidative pentose phosphate pathway (PPP) flux and glycolysis pathway in human lung cancer by increasing the activity of 6-phospho-gluconate dehydrogenase (6PGD) and α-enolase (ENO1). Furthermore, PRMT6 methylated R324 of 6PGD to enhancing its activity; while methylation at R9 and R372 of ENO1 promotes formation of active ENO1 dimers and 2-phosphoglycerate (2-PG) binding to ENO1, respectively. Lastly, targeting PRMT6 blocked the oxidative PPP flux, glycolysis pathway, and tumor growth, as well as enhanced the anti-tumor effects of cisplatin in lung cancer. Together, this study demonstrates that PRMT6 acts as a post-translational modification (PTM) regulator of glucose metabolism, which leads to the pathogenesis of lung cancer. It was proven that the PRMT6-6PGD/ENO1 regulatory axis is an important determinant of carcinogenesis and may become a promising cancer therapeutic strategy.
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Post-translational modification of host proteins induced by pathogenic microorganism plays a critical role in the development, treatment and prevention of diseases. Mycobacterium tuberculosis ( Mtb) is an intracellular pathogen that causes tuberculosis. The post-translational modification induced by Mtb infection is essential in the development and progression of tuberculosis. In recent years, it has been found that Mtb-induced host protein acetylation plays an important role in the regulation of host immunity against tuberculosis, which significantly affects the development of tuberculosis. This review focused on the role and mechanism of Mtb in regulating host protein acetylation, aiming to provide reference for future investigation on potential immunotherapy for tuberculosis.
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Ubiquitination is a unique protein post-translational modification in eukaryotic cells. It regulates a variety of physiological processes, such as protein homeostasis, cell cycle, immune response, DNA repair, and vesicle transport. In view of the importance of ubiquitin in live cells, pathogens have derived a series of effector proteins targeting the host ubiquitin process in the long-term evolutionary process, aiming to regulate the ubiquitin process in the host and render an internal environment suitable for the growth and reproduction of pathogens. Legionella pneumophila is a gram-negative bacterium that is responsible for Legionella pneumoniae pneumonia, causing fever and lung infection with a fatality rate of 15% ~ 30% in severe cases. The Dot / Icm type IV secretory system is the most important virulence system in the infection of Legionella pneumophila. In the process of infecting host cells, Legionella pneumophila uses this secretion system to secrete more than 330 effector proteins to assist bacterial survival, proliferation and escape in host cells. Several effector proteins of Legionella pneumophila regulate the host ubiquitination process directly or indirectly. Recent studies found that some effectors can mediate non-canonical ubiquitination of host proteins, which is different from the classical ubiquitination process. Here, we introduce the latest research progress of novel ubiquitination mediated by effecting proteins of Legionella pneumophila, providing a reference for understanding the important role of ubiquitination in the pathogenesis of Legionella pneumophila.
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During the normal process of biological growth and development, NF-E2-related factor 1 (Nrf1/ Nfe2l1) plays a unique role in maintaining intracellular homeostasis and organ integrity. The deficiency of Nrf1 will lead to severe oxidative stress, genomic instability, and result in liver cancer, neurodegenerative disorder and other diseases. In recent years, it has been found that Nrf1 could yield different activated isoforms or even opposite activity isoforms in a variety of ways to perform distinct functions, and the distribution of these isoforms may play a vital role in the process of tumor development. Therefore, to gain a better understanding of the function of Nrf1 isoforms in cells and tissues, we first briefly introduced its discovery process, and demonstrated the multiple mechanisms of distinct isoform production including selective shear processing, internal selective translation initiation, and post-translation shear processing. More importantly, three different post-translational processing models, transmembrane dynamic processing, site-specific processing, ubiquitin-dependent processing, were expounded in detail. Furthermore, the biological function of different isoforms of Nrf1 and its role in diseases were also summarized in the last section. Collectively, we focus on the production mechanism of different isoforms of Nrf1 and their roles in diseases so as to lay a foundation for finding new strategies for tumor treatment.
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Connexin (Cx), a multigene-encoded transmembrane protein family, forms either gap junctions ( GJ) or hemichannels (HC) to mediate intercellular communication in plasma mem¬brane between adjacent cells or interacts with proteins by its car- boxyl terminal in the cytoplasm to participate in the process of tumor cell proliferation, apoptosis, necrosis, invasion, metasta¬sis, drug resistance and stem cell characteristics.However, mi- slocalization of Cx in cytoplasm or nucleus often occurs in many tumors, and involved in the occurrence and development of tumors.Subcellular localization of Cx is affected by post-transla- tional modifications, including phosphorylation, ubiquitination, and acetylation.In this paper the classification and function of Cx, the relationship between subcellular localization of Cx and tumorigenesis and the regulation of post-translational modifica¬tion on Cx are reviewed in order to provide new ideas for the study of Cx as a potential target for cancer therapy.
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SUMOylation is an important post-translational modification of proteins. Similar to ubiquitylation, SUMOylation is the process that the small ubiquitin-like modifier (SUMO) proteins are specifically and covalently binding to lysine residues of substrate proteins. Through SUMOylation, the physiological functions and pathological processes of cells are well controlled and balanced, and its abnormal activation has been reported in various tumors. Therefore, SUMOylation has been a potential target for anti-tumor drug development. In this review, we summarize recent advances on development of inhibitors targeting SUMOylation pathway and their antitumor properties.
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@#Proteins in the human body are usually made of 20 natural amino acids.Through different amino acid combinations and isomerization, proteins of diverse functions are built.An emerging genetic code expansion technology can introduce unnatural amino acids into specific sites of target protein, endowing the protein with new biological characteristics including covalently binding with proximal proteins, carrying fluorescence, and mimicking specific protein post-translational modifications.In this paper, based on the structure and function of unnatural amino acids, the applications of different types of unnatural amino acids in regulating protein''s stability, studying protein''s conformation, expression level, and localization, and uncovering heretofore unknown protein-protein interactions were reviewed.Besides, genetic code expansion of unnatural amino acids is anticipated to find broad utilities in biomedicine by bringing new ideas and methods to the design and optimization of biologics.
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【Objective】 To compare the effects of human albumin products from different domestic manufacturers on human stem cell culture. 【Methods】 Human CD34+ cells were cultured by supplementing human albumin from different manufacturers to serum-free medium, and the expansion ratios of cells within 15 days were counted. Post translational modifications of human albumin products were studied by LC-MS. 【Results】 Supplementing plasma-derived human albumin(pd-alb) to serum-free medium, the expansion ratios of cells could reach up to 20.6±5.7, while the recombinant human albumin(rhAlb) resulted in no significant expansion within 15 days. LC-MS showed significant differences in post-translational modifications from different human albumin products. 【Conclusion】 Different human albumin products showed significantly different effects in the expansion of stem cells due to different sources, processes and stabilizers. Pd-alb products were better for stem cell culture than rhAlb products. There are significant differences between pd-albs and rhAlbs in post-translational modification, but whether these differences are related to stem cell expansion remains to be studied.
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The proteasome is the main complex for specific protein degradation in eukaryotic cells, which plays a key role in protein quality control and cell homeostasis maintenance. It is found that abnormal content or function of the proteasome can lead to many human serious diseases such as cancer and neurodegenerative disorders, and several targeted drugs have been developed for the regulation of proteasome activity. Therefore, it is of great academic value and clinical significance to strengthen the research on the precise regulation mechanism of proteasome activity. The content, assembly and activity of the proteasome are regulated rigorously by multiple levels. In this paper, we summarize the composition subunits, structural features, transcriptional regulation and assembly mechanism of proteasome, and focus on the mechanistic regulation and biological significance of post-translational modifications such as phosphorylation, ubiquitination and acetylation on proteasome, which might be helpful to reveal the regulation mechanism of proteasome in the near future.
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Epigenetic regulation through post-translational modification of histones, especially methylation, is wellconserved in evolution. Although there are several insect genomes sequenced, an analysis with a focus on theirepigenetic repertoire is limited. We have utilized a novel work-flow to identify one or more domains as highpriority domain (HPD), if present in at least 50% of the genes of a given functional class in the referencegenome, namely, that of Drosophila melanogaster. Based on this approach, we have mined histone methyltransferases and demethylases from the whole genome sequence of Aedes aegypti (Diptera), the pea aphidAcyrthosiphon pisum, the triatomid bug Rhodnius prolixus (Hemiptera), the honeybee Apis mellifera (Hymenoptera), the silkworm Bombyx mori (Lepidoptera) and the red flour beetle Tribolium castaneum(Coleoptera). We identified 38 clusters consisting of arginine methyltransferases, lysine methyltransferases anddemethylases using OrthoFinder, and the presence of HPD was queried in these sequences using InterProScan.This approach led us to identify putative novel members and currently inaccurate ones. Other than the highpriority domains, these proteins contain shared and unique domains that can mediate protein–protein interaction. Phylogenetic analysis indicates that there is different extent of protein sequence similarity; averagesimilarity between histone lysine methyltransferases varies from 41% (for active mark) to 48% (for repressivemark), arginine methyltransferases is 51%, and demethylases is 52%. The method utilized here facilitatesreliable identification of desired functional class in newly sequenced genomes
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Protein lysine methylation is a prevalent post-translational modification (PTM) and plays critical roles in all domains of life. However, its extent and function in photosynthetic organisms are still largely unknown. Cyanobacteria are a large group of prokaryotes that carry out oxygenic photosynthesis and are applied extensively in studies of photosynthetic mechanisms and environmental adaptation. Here we integrated propionylation of monomethylated proteins, enrichment of the modified peptides, and mass spectrometry (MS) analysis to identify monomethylated proteins in Synechocystis sp. PCC 6803 (Synechocystis). Overall, we identified 376 monomethylation sites in 270 proteins, with numerous monomethylated proteins participating in photosynthesis and carbon metabolism. We subsequently demonstrated that CpcM, a previously identified asparagine methyltransferase in Synechocystis, could catalyze lysine monomethylation of the potential aspartate aminotransferase Sll0480 both in vivo and in vitro and regulate the enzyme activity of Sll0480. The loss of CpcM led to decreases in the maximum quantum yield in primary photosystem II (PSII) and the efficiency of energy transfer during the photosynthetic reaction in Synechocystis. We report the first lysine monomethylome in a photosynthetic organism and present a critical database for functional analyses of monomethylation in cyanobacteria. The large number of monomethylated proteins and the identification of CpcM as the lysine methyltransferase in cyanobacteria suggest that reversible methylation may influence the metabolic process and photosynthesis in both cyanobacteria and plants.
Subject(s)
Bacterial Proteins/metabolism , Lysine/metabolism , Methyltransferases/metabolism , Photosynthesis , Protein Processing, Post-Translational , Synechocystis/growth & developmentABSTRACT
High mobility group box 1 (HMGB1) is a highly conserved and evolutionarily non-histone chromosomal protein that is modified by different PTMs,such as acetylation,glycosylation,phosphorylation,ADP-ribosylation,methylation and oxidation,which induces HMGB1 translocation to the cytosol or releases to the extracellular secretion following various stimuli,and its biological function also changes with the location change.This review aims to summarize the structure,the effect of PTMs on HMGB1 location and function.
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Protein glycosylation is one of the most important protein post-translational modifications that can affect life activities by endowing the protein with various structural and functional features. Saliva is an easy-to-obtain, noninvasive body fluid that contains components originating from serum, gingival crevicular fluid, and oropharyngeal mucosae. In recent years, understanding of saliva has been constantly updated with the developments in related research. Studies have shown that salivary proteins can be used as diagnostic markers for certain diseases, and changes of protein glycosylation in saliva are generally considered to be related to many diseases. In this review, salivary protein glycosylation and its relationship with systemic and oral diseases were discussed.
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Dynamic changes of the post-translational O-GlcNAc modification (O-GlcNAcylation) are controlled by O-linked β-N-acetylglucosamine (O-GlcNAc) transferase (OGT) and the glycoside hydrolase O-GlcNAcase (OGA) in cells. O-GlcNAcylation often occurs on serine (Ser) and threonine (Thr) residues of the specific substrate proteins via the addition of O-GlcNAc group by OGT. It has been known that O-GlcNAcylation is not only involved in many fundamental cellular processes, but also plays an important role in cancer development through various mechanisms. Recently, accumulating data reveal that O-GlcNAcylation at histones or non-histone proteins can lead to the start of the subsequent biological processes, suggesting that O-GlcNAcylation as 'protein code' or 'histone code' may provide recognition platforms or executive instructions for subsequent recruitment of proteins to carry out the specific functions. In this review, we summarize the interaction of O-GlcNAcylation and epigenetic changes, introduce recent research findings that link crosstalk between O-GlcNAcylation and epigenetic changes, and speculate on the potential coordination role of O-GlcNAcylation with epigenetic changes in intracellular biological processes.
Subject(s)
Animals , Humans , Acetylglucosamine , Metabolism , Epigenesis, Genetic , Glycoside Hydrolases , Metabolism , N-Acetylglucosaminyltransferases , Metabolism , Neoplasms , Genetics , Metabolism , Protein Processing, Post-TranslationalABSTRACT
Lafora disease (LD), an autosomal recessive and fatal form of neurodegenerative disorder, is characterized by the presence of polyglucosan inclusions in the affected tissues including the brain. LD can be caused by defects either in the EPM2A gene coding for the laforin protein phosphatase or the NHLRC1 gene coding for the malin ubiquitin ligase. Since the clinical symptoms of LD patients representing the two genetic groups are very similar and since malin is known to interact with laforin, we were curious to examine the possibility that the two proteins regulate each other’s function. Using cell biological assays we demonstrate here that (i) malin promotes its own degradation via autoubiquitination, (ii) laforin prevents the auto-degradation of malin by presenting itself as a substrate and (iii) malin preferentially degrades the phosphatase-inactive laforin monomer. Our results that laforin and malin regulate each other’s stability and activity offers a novel and attractive model to explain the molecular basis of locus heterogeneity observed in LD.
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OBJECTIVE: To identify several kinds of post-translational modifications in recombinant protein pharmaceuticals by MS/MS. METHODS: Firstly the proteins were digested with enzymes, and the obtained peptides were analyzed by UPLC-MS. By MS analysis, peptides with post-translational modifications could be detected, then it was then identified by MS/MS. RESULTS: Using MS/MS, the disulfide bonds, peptides with similar molecular mass, O-glycosylation site and the type of N-linked oligosaccharides were identified. CONCLUSION: MS/MS analvsis can make up for the deficiency of enzyme digestion in some extent, and provide more sufficient evidence for the identification of post-translational modifications.
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Since their successful launch, the recombinant coagulation factors have been effective in the treatment and prophylaxis of respective deficiencies, and started to replace plasma-derived coagulation factors. However, immunogenicity and induction of inhibitors associated with the uses of these recombinant products have drawn certain attention. This manuscript reviews the structural differences between several major recombinant coagulation factors and their plasma-derived counteiparts, including sequences and many forms of post-translational modifications, and discusses the possible effects of these structural differences on the pharmacology, efficacy and pharmacokinetics of the products. The demonstration of structural differences and underlying mechanisms helps to improve the production yield and quality of recombinant coagulation factors, which is of significant clinical importance.
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Since their successful launch, the recombinant coagulation factors have been effective in the treatment and prophylaxis of respective deficiencies, and started to replace plasma-derived coagulation factors. However, immunogenicity and induction of inhibitors associated with the uses of these recombinant products have drawn certain attention. This manuscript reviews the structural differences between several major recombinant coagulation factors and their plasma-derived counterparts, including sequences and many forms of post-translational modifications, and discusses the possible effects of these structural differences on the pharmacology, efficacy and pharmacokinetics of the products. The demonstration of structural differences and underlying mechanisms helps to improve the production yield and quality of recombinant coagulation factors, which is of significant clinical importance.
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Post-translational modifications (PTMs) of transcription factors play a crucial role in regulating metabolic homeostasis. These modifications include phosphorylation, methylation, acetylation, ubiquitination, SUMOylation, and O-GlcNAcylation. Recent studies have shed light on the importance of lysine acetylation at nonhistone proteins including transcription factors. Acetylation of transcription factors affects subcellular distribution, DNA affinity, stability, transcriptional activity, and current investigations are aiming to further expand our understanding of the role of lysine acetylation of transcription factors. In this review, we summarize recent studies that provide new insights into the role of protein lysine-acetylation in the transcriptional regulation of metabolic homeostasis.