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Santos NP, Soh WT, Demir F, Tenhaken R, Briza P, Huesgen PF, Brandstetter H, Dall E. Phytocystatin 6 is a context-dependent, tight-binding inhibitor of Arabidopsis thaliana legumain isoform β. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 116:1681-1695. [PMID: 37688791 PMCID: PMC10952133 DOI: 10.1111/tpj.16458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 08/24/2023] [Accepted: 08/28/2023] [Indexed: 09/11/2023]
Abstract
Plant legumains are crucial for processing seed storage proteins and are critical regulators of plant programmed cell death. Although research on legumains boosted recently, little is known about their activity regulation. In our study, we used pull-down experiments to identify AtCYT6 as a natural inhibitor of legumain isoform β (AtLEGβ) in Arabidopsis thaliana. Biochemical analysis revealed that AtCYT6 inhibits both AtLEGβ and papain-like cysteine proteases through two separate cystatin domains. The N-terminal domain inhibits papain-like proteases, while the C-terminal domain inhibits AtLEGβ. Furthermore, we showed that AtCYT6 interacts with legumain in a substrate-like manner, facilitated by a conserved asparagine residue in its reactive center loop. Complex formation was additionally stabilized by charged exosite interactions, contributing to pH-dependent inhibition. Processing of AtCYT6 by AtLEGβ suggests a context-specific regulatory mechanism with implications for plant physiology, development, and programmed cell death. These findings enhance our understanding of AtLEGβ regulation and its broader physiological significance.
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Affiliation(s)
- Naiá P. Santos
- Department of Biosciences and Medical BiologyUniversity of Salzburg5020SalzburgAustria
| | - Wai Tuck Soh
- Department of Biosciences and Medical BiologyUniversity of Salzburg5020SalzburgAustria
- Present address:
Max Planck Institute for Multidisciplinary SciencesD‐37077GöttingenGermany
| | - Fatih Demir
- Central Institute for Engineering, Electronics and Analytics52428JülichZEA‐3, Forschungszentrum JülichGermany
- Present address:
Department of BiomedicineAarhus University8000Aarhus CDenmark
| | - Raimund Tenhaken
- Department of Environment and BiodiversityUniversity of Salzburg5020SalzburgAustria
| | - Peter Briza
- Department of Biosciences and Medical BiologyUniversity of Salzburg5020SalzburgAustria
| | - Pitter F. Huesgen
- Central Institute for Engineering, Electronics and Analytics52428JülichZEA‐3, Forschungszentrum JülichGermany
- CECADMedical Faculty and University Hospital, University of Cologne50931CologneGermany
- Institute for Biochemistry, Faculty of Mathematics and Natural SciencesUniversity of Cologne50674CologneGermany
| | - Hans Brandstetter
- Department of Biosciences and Medical BiologyUniversity of Salzburg5020SalzburgAustria
| | - Elfriede Dall
- Department of Biosciences and Medical BiologyUniversity of Salzburg5020SalzburgAustria
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2
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Moises JE, Regl C, Hinterholzer A, Huber CG, Schubert M. Unambiguous Identification of Glucose-Induced Glycation in mAbs and other Proteins by NMR Spectroscopy. Pharm Res 2023; 40:1341-1353. [PMID: 36510116 PMCID: PMC10338404 DOI: 10.1007/s11095-022-03454-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 11/30/2022] [Indexed: 12/14/2022]
Abstract
OBJECTIVE Glycation is a non-enzymatic and spontaneous post-translational modification (PTM) generated by the reaction between reducing sugars and primary amine groups within proteins. Because glycation can alter the properties of proteins, it is a critical quality attribute of therapeutic monoclonal antibodies (mAbs) and should therefore be carefully monitored. The most abundant product of glycation is formed by glucose and lysine side chains resulting in fructoselysine after Amadori rearrangement. In proteomics, which routinely uses a combination of chromatography and mass spectrometry to analyze PTMs, there is no straight-forward way to distinguish between glycation products of a reducing monosaccharide and an additional hexose within a glycan, since both lead to a mass difference of 162 Da. METHODS To verify that the observed mass change is indeed a glycation product, we developed an approach based on 2D NMR spectroscopy spectroscopy and full-length protein samples denatured using high concentrations of deuterated urea. RESULTS The dominating β-pyranose form of the Amadori product shows a characteristic chemical shift correlation pattern in 1H-13C HSQC spectra suited to identify glucose-induced glycation. The same pattern was observed in spectra of a variety of artificially glycated proteins, including two mAbs, as well as natural proteins. CONCLUSION Based on this unique correlation pattern, 2D NMR spectroscopy can be used to unambiguously identify glucose-induced glycation in any protein of interest. We provide a robust method that is orthogonal to MS-based methods and can also be used for cross-validation.
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Affiliation(s)
- Jennifer E Moises
- Department of Biosciences and Medical Biology, University of Salzburg, Hellbrunner Strasse 34, 5020, Salzburg, Austria
| | - Christof Regl
- Department of Biosciences and Medical Biology, University of Salzburg, Hellbrunner Strasse 34, 5020, Salzburg, Austria
- Christian Doppler Laboratory for Innovative Tools for Biosimilar Characterization, University of Salzburg, Hellbrunner Strasse 34, 5020, Salzburg, Austria
| | - Arthur Hinterholzer
- Department of Biosciences and Medical Biology, University of Salzburg, Hellbrunner Strasse 34, 5020, Salzburg, Austria
- Christian Doppler Laboratory for Innovative Tools for Biosimilar Characterization, University of Salzburg, Hellbrunner Strasse 34, 5020, Salzburg, Austria
| | - Christian G Huber
- Department of Biosciences and Medical Biology, University of Salzburg, Hellbrunner Strasse 34, 5020, Salzburg, Austria
- Christian Doppler Laboratory for Innovative Tools for Biosimilar Characterization, University of Salzburg, Hellbrunner Strasse 34, 5020, Salzburg, Austria
| | - Mario Schubert
- Department of Biosciences and Medical Biology, University of Salzburg, Hellbrunner Strasse 34, 5020, Salzburg, Austria.
- Christian Doppler Laboratory for Innovative Tools for Biosimilar Characterization, University of Salzburg, Hellbrunner Strasse 34, 5020, Salzburg, Austria.
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3
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Sampognaro PJ, Arya S, Knudsen GM, Gunderson EL, Sandoval-Perez A, Hodul M, Bowles K, Craik CS, Jacobson MP, Kao AW. Mutations in α-synuclein, TDP-43 and tau prolong protein half-life through diminished degradation by lysosomal proteases. Mol Neurodegener 2023; 18:29. [PMID: 37131250 PMCID: PMC10155372 DOI: 10.1186/s13024-023-00621-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Accepted: 04/21/2023] [Indexed: 05/04/2023] Open
Abstract
BACKGROUND Autosomal dominant mutations in α-synuclein, TDP-43 and tau are thought to predispose to neurodegeneration by enhancing protein aggregation. While a subset of α-synuclein, TDP-43 and tau mutations has been shown to increase the structural propensity of these proteins toward self-association, rates of aggregation are also highly dependent on protein steady state concentrations, which are in large part regulated by their rates of lysosomal degradation. Previous studies have shown that lysosomal proteases operate precisely and not indiscriminately, cleaving their substrates at very specific linear amino acid sequences. With this knowledge, we hypothesized that certain coding mutations in α-synuclein, TDP-43 and tau may lead to increased protein steady state concentrations and eventual aggregation by an alternative mechanism, that is, through disrupting lysosomal protease cleavage recognition motifs and subsequently conferring protease resistance to these proteins. RESULTS To test this possibility, we first generated comprehensive proteolysis maps containing all of the potential lysosomal protease cleavage sites for α-synuclein, TDP-43 and tau. In silico analyses of these maps indicated that certain mutations would diminish cathepsin cleavage, a prediction we confirmed utilizing in vitro protease assays. We then validated these findings in cell models and induced neurons, demonstrating that mutant forms of α-synuclein, TDP-43 and tau are degraded less efficiently than wild type despite being imported into lysosomes at similar rates. CONCLUSIONS Together, this study provides evidence that pathogenic mutations in the N-terminal domain of α-synuclein (G51D, A53T), low complexity domain of TDP-43 (A315T, Q331K, M337V) and R1 and R2 domains of tau (K257T, N279K, S305N) directly impair their own lysosomal degradation, altering protein homeostasis and increasing cellular protein concentrations by extending the degradation half-lives of these proteins. These results also point to novel, shared, alternative mechanism by which different forms of neurodegeneration, including synucleinopathies, TDP-43 proteinopathies and tauopathies, may arise. Importantly, they also provide a roadmap for how the upregulation of particular lysosomal proteases could be targeted as potential therapeutics for human neurodegenerative disease.
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Affiliation(s)
- Paul J. Sampognaro
- Memory and Aging Center, Department of Neurology, University of California, San Francisco, CA USA
- Neuromuscular Division, Department of Neurology, University of California, San Francisco, CA USA
| | - Shruti Arya
- Memory and Aging Center, Department of Neurology, University of California, San Francisco, CA USA
| | | | - Emma L. Gunderson
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA USA
| | - Angelica Sandoval-Perez
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA USA
| | - Molly Hodul
- Memory and Aging Center, Department of Neurology, University of California, San Francisco, CA USA
| | - Kathryn Bowles
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, USA
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh Medical School, Edinburgh, UK
| | - Charles S. Craik
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA USA
| | - Matthew P. Jacobson
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA USA
| | - Aimee W. Kao
- Memory and Aging Center, Department of Neurology, University of California, San Francisco, CA USA
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4
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Hemu X, Chan NY, Liew HT, Hu S, Zhang X, Serra A, Lescar J, Liu CF, Tam JP. Substrate-binding glycine residues are major determinants for hydrolase and ligase activity of plant legumains. THE NEW PHYTOLOGIST 2023; 238:1534-1545. [PMID: 36843268 DOI: 10.1111/nph.18841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 02/17/2023] [Indexed: 06/18/2023]
Abstract
Peptide asparaginyl ligases (PALs) are useful tools for precision modifications of proteins and live-cell surfaces by ligating peptides after Asn/Asp (Asx). They share high sequence and structural similarity to plant legumains that are generally known as asparaginyl endopeptidases (AEPs), thus making it challenging to identify PALs from AEPs. In this study, we investigate 875 plant species from algae to seed plants with available sequence data in public databases to identify new PALs. We conducted evolutionary trace analysis on 1500 plant legumains, including eight known PALs, to identify key residues that could differentiate ligases and proteases, followed by recombinant expression and functional validation of 16 novel legumains. Previously, we showed that the substrate-binding sequences flanking the catalytic site can strongly influence the enzymatic direction of a legumain and which we named as ligase-activity determinants (LADs). Here, we show that two conserved substrate-binding Gly residues of LADs are critical, but negative determinants for ligase activity. Our results suggest that specific glycine residues are molecular determinants to identify PALs and AEPs as two different legumain subfamilies, accounting for c. 1% and 88%, respectively.
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Affiliation(s)
- Xinya Hemu
- School of Biological Sciences, Synzymes and Natural Products Center (SYNC), Nanyang Technological University, 60 Nanyang Drive, Singapore City, 637551, Singapore
| | - Ning-Yu Chan
- School of Biological Sciences, Synzymes and Natural Products Center (SYNC), Nanyang Technological University, 60 Nanyang Drive, Singapore City, 637551, Singapore
| | - Heng Tai Liew
- School of Biological Sciences, Synzymes and Natural Products Center (SYNC), Nanyang Technological University, 60 Nanyang Drive, Singapore City, 637551, Singapore
| | - Side Hu
- NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, Singapore City, 637921, Singapore
| | - Xiaohong Zhang
- School of Biological Sciences, Synzymes and Natural Products Center (SYNC), Nanyang Technological University, 60 Nanyang Drive, Singapore City, 637551, Singapore
| | - Aida Serra
- School of Biological Sciences, Synzymes and Natural Products Center (SYNC), Nanyang Technological University, 60 Nanyang Drive, Singapore City, 637551, Singapore
- Neuroscience Area, +Pec Proteomics Research Group (+PPRG), Faculty of Medicine, Biomedical Research Institute of Lleida Dr. Pifarré Foundation (IRB Lleida), University of Lleida, Av. Rovira Roure, 80, Lleida, 25198, Spain
| | - Julien Lescar
- NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, Singapore City, 637921, Singapore
| | - Chuan-Fa Liu
- School of Biological Sciences, Synzymes and Natural Products Center (SYNC), Nanyang Technological University, 60 Nanyang Drive, Singapore City, 637551, Singapore
| | - James P Tam
- School of Biological Sciences, Synzymes and Natural Products Center (SYNC), Nanyang Technological University, 60 Nanyang Drive, Singapore City, 637551, Singapore
- NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, Singapore City, 637921, Singapore
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5
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Wilkinson IVL, Castro-Falcón G, Roda-Serrat MC, Purdy TN, Straetener J, Brauny MM, Maier L, Brötz-Oesterhelt H, Christensen LP, Sieber SA, Hughes CC. The Cyanobacterial "Nutraceutical" Phycocyanobilin Inhibits Cysteine Protease Legumain. Chembiochem 2023; 24:e202200455. [PMID: 36538283 DOI: 10.1002/cbic.202200455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 12/19/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022]
Abstract
The blue biliprotein phycocyanin, produced by photo-autotrophic cyanobacteria including spirulina (Arthrospira) and marketed as a natural food supplement or "nutraceutical," is reported to have anti-inflammatory, antioxidant, immunomodulatory, and anticancer activity. These diverse biological activities have been specifically attributed to the phycocyanin chromophore, phycocyanobilin (PCB). However, the mechanism of action of PCB and the molecular targets responsible for the beneficial properties of PCB are not well understood. We have developed a procedure to rapidly cleave the PCB pigment from phycocyanin by ethanolysis and then characterized it as an electrophilic natural product that interacts covalently with thiol nucleophiles but lacks any appreciable cytotoxicity or antibacterial activity against common pathogens and gut microbes. We then designed alkyne-bearing PCB probes for use in chemical proteomics target deconvolution studies. Target identification and validation revealed the cysteine protease legumain (also known as asparaginyl endopeptidase, AEP) to be a target of PCB. Inhibition of this target may account for PCB's diverse reported biological activities.
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Affiliation(s)
- Isabel V L Wilkinson
- Center for Protein Assemblies (CPA), Department of Chemistry, Technical University of Munich, Ernst-Otto-Fischer-Str. 8, 85748, Garching, Germany
| | - Gabriel Castro-Falcón
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, CA 92093, USA
| | - Maria C Roda-Serrat
- Department of Green Technology, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark
| | - Trevor N Purdy
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, CA 92093, USA
| | - Jan Straetener
- Department of Microbial Bioactive Compounds, Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, 72076, Tübingen, Germany
| | - Melanie M Brauny
- Cluster of Excellence EXC 2124, Controlling Microbes to Fight Infection, University of Tübingen, 72076, Tübingen, Germany
- Microbiome-Host-Interaction Lab, Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, 72076, Tübingen, Germany
| | - Lisa Maier
- Cluster of Excellence EXC 2124, Controlling Microbes to Fight Infection, University of Tübingen, 72076, Tübingen, Germany
- Microbiome-Host-Interaction Lab, Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, 72076, Tübingen, Germany
| | - Heike Brötz-Oesterhelt
- Department of Microbial Bioactive Compounds, Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, 72076, Tübingen, Germany
- Cluster of Excellence EXC 2124, Controlling Microbes to Fight Infection, University of Tübingen, 72076, Tübingen, Germany
- German Center for Infection Research, Partner Site Tübingen, 72076, Tübingen, Germany
| | - Lars P Christensen
- Department of Green Technology, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark
| | - Stephan A Sieber
- Center for Protein Assemblies (CPA), Department of Chemistry, Technical University of Munich, Ernst-Otto-Fischer-Str. 8, 85748, Garching, Germany
| | - Chambers C Hughes
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, CA 92093, USA
- Department of Microbial Bioactive Compounds, Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, 72076, Tübingen, Germany
- Cluster of Excellence EXC 2124, Controlling Microbes to Fight Infection, University of Tübingen, 72076, Tübingen, Germany
- German Center for Infection Research, Partner Site Tübingen, 72076, Tübingen, Germany
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6
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Hu S, El Sahili A, Kishore S, Wong YH, Hemu X, Goh BC, Zhipei S, Wang Z, Tam JP, Liu CF, Lescar J. Structural basis for proenzyme maturation, substrate recognition, and ligation by a hyperactive peptide asparaginyl ligase. THE PLANT CELL 2022; 34:4936-4949. [PMID: 36099055 PMCID: PMC9709980 DOI: 10.1093/plcell/koac281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 08/28/2022] [Indexed: 06/15/2023]
Abstract
Peptide ligases are versatile enzymes that can be utilized for precise protein conjugation for bioengineering applications. Hyperactive peptide asparaginyl ligases (PALs), such as butelase-1, belong to a small class of enzymes from cyclotide-producing plants that can perform site-specific, rapid ligation reactions after a target peptide asparagine/aspartic acid (Asx) residue binds to the active site of the ligase. How PALs specifically recognize their polypeptide substrates has remained elusive, especially at the prime binding side of the enzyme. Here we report crystal structures that capture VyPAL2, a catalytically efficient PAL from Viola yedoensis, in an activated state, with and without a bound substrate. The bound structure shows one ligase with the N-terminal polypeptide tail from another ligase molecule trapped at its active site, revealing how Asx inserts in the enzyme's S1 pocket and why a hydrophobic residue is required at the P2' position. Besides illustrating the anchoring role played by P1 and P2' residues, these results uncover a role for the Gatekeeper residue at the surface of the S2 pocket in shifting the nonprime portion of the substrate and, as a result, the activity toward ligation or hydrolysis. These results suggest a picture for proenzyme maturation in the vacuole and will inform the rational design of peptide ligases with tailored specificities.
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Affiliation(s)
- Side Hu
- School of Biological Sciences, Nanyang Technological University, Singapore City, 637551, Singapore
- NTU Institute of Structural Biology, Nanyang Technological University, Singapore City, 636921, Singapore
| | - Abbas El Sahili
- School of Biological Sciences, Nanyang Technological University, Singapore City, 637551, Singapore
- NTU Institute of Structural Biology, Nanyang Technological University, Singapore City, 636921, Singapore
| | - Srujana Kishore
- School of Biological Sciences, Nanyang Technological University, Singapore City, 637551, Singapore
- NTU Institute of Structural Biology, Nanyang Technological University, Singapore City, 636921, Singapore
| | - Yee Hwa Wong
- School of Biological Sciences, Nanyang Technological University, Singapore City, 637551, Singapore
- NTU Institute of Structural Biology, Nanyang Technological University, Singapore City, 636921, Singapore
| | - Xinya Hemu
- School of Biological Sciences, Nanyang Technological University, Singapore City, 637551, Singapore
| | - Boon Chong Goh
- NTU Institute of Structural Biology, Nanyang Technological University, Singapore City, 636921, Singapore
- Antimicrobial Resistance Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology Centre, Singapore City, 138602, Singapore
| | - Sang Zhipei
- School of Biological Sciences, Nanyang Technological University, Singapore City, 637551, Singapore
| | - Zhen Wang
- School of Biological Sciences, Nanyang Technological University, Singapore City, 637551, Singapore
| | - James P Tam
- School of Biological Sciences, Nanyang Technological University, Singapore City, 637551, Singapore
| | - Chuan-Fa Liu
- School of Biological Sciences, Nanyang Technological University, Singapore City, 637551, Singapore
| | - Julien Lescar
- School of Biological Sciences, Nanyang Technological University, Singapore City, 637551, Singapore
- NTU Institute of Structural Biology, Nanyang Technological University, Singapore City, 636921, Singapore
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7
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Elamin T, Brandstetter H, Dall E. Legumain Activity Is Controlled by Extended Active Site Residues and Substrate Conformation. Int J Mol Sci 2022; 23:12548. [PMID: 36293424 PMCID: PMC9604545 DOI: 10.3390/ijms232012548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 10/11/2022] [Accepted: 10/13/2022] [Indexed: 11/16/2022] Open
Abstract
Legumain is a lysosomal cysteine protease with strict specificity for cleaving after asparagine residues. By sequence comparison, legumain belongs to MEROPS clan CD of the cysteine proteases, which indicates its structural and mechanistic relation to caspases. Contrasting caspases, legumain harbors a pH-dependent ligase activity in addition to the protease activity. Although we already have a significant body of knowledge on the catalytic activities of legumain, many mechanistic details are still elusive. In this study, we provide evidence that extended active site residues and substrate conformation are steering legumain activities. Biochemical experiments and bioinformatics analysis showed that the catalytic Cys189 and His148 residues are regulated by sterically close Glu190, Ser215 and Asn42 residues. While Glu190 serves as an activity brake, Ser215 and Asn42 have a favorable effect on legumain protease activity. Mutagenesis studies using caspase-9 as model enzyme additionally showed that a similar Glu190 activity brake is also implemented in the caspases. Furthermore, we show that the substrate's conformational flexibility determines whether it will be hydrolyzed or ligated by legumain. The functional understanding of the extended active site residues and of substrate prerequisites will allow us to engineer proteases with increased enzymatic activity and better ligase substrates, with relevance for biotechnological applications.
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Affiliation(s)
| | | | - Elfriede Dall
- Department of Biosciences and Medical Biology, University of Salzburg, 5020 Salzburg, Austria
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8
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Elamin T, Santos NP, Briza P, Brandstetter H, Dall E. Structural and functional studies of legumain-mycocypin complexes revealed a competitive, exosite-regulated mode of interaction. J Biol Chem 2022; 298:102502. [PMID: 36116553 PMCID: PMC9579014 DOI: 10.1016/j.jbc.2022.102502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 09/10/2022] [Accepted: 09/12/2022] [Indexed: 12/01/2022] Open
Abstract
Under pathophysiologic conditions such as Alzheimer’s disease and cancer, the endolysosomal cysteine protease legumain was found to translocate to the cytosol, the nucleus, and the extracellular space. These noncanonical localizations demand for a tight regulation of legumain activity, which is in part conferred by protein inhibitors. While there is a significant body of knowledge on the interaction of human legumain with endogenous cystatins, only little is known on its regulation by fungal mycocypins. Mycocypins are characterized by (i) versatile, plastic surface loops allowing them to inhibit different classes of enzymes and (ii) a high resistance toward extremes of pH and temperature. These properties make mycocypins attractive starting points for biotechnological and medical applications. In this study, we show that mycocypins utilize an adaptable reactive center loop to target the active site of legumain in a substrate-like manner. The interaction was further stabilized by variable, isoform-specific exosites, converting the substrate recognition into inhibition. Additionally, we found that selected mycocypins were capable of covalent complex formation with legumain by forming a disulfide bond to the active site cysteine. Furthermore, our inhibition studies with other clan CD proteases suggested that mycocypins may serve as broad-spectrum inhibitors of clan CD proteases. Our studies uncovered the potential of mycocypins as a new scaffold for drug development, providing the basis for the design of specific legumain inhibitors.
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Affiliation(s)
- Tasneem Elamin
- Department of Biosciences and Medical Biology, University of Salzburg, 5020 Salzburg, Austria
| | - Naiá P Santos
- Department of Biosciences and Medical Biology, University of Salzburg, 5020 Salzburg, Austria
| | - Peter Briza
- Department of Biosciences and Medical Biology, University of Salzburg, 5020 Salzburg, Austria
| | - Hans Brandstetter
- Department of Biosciences and Medical Biology, University of Salzburg, 5020 Salzburg, Austria
| | - Elfriede Dall
- Department of Biosciences and Medical Biology, University of Salzburg, 5020 Salzburg, Austria.
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9
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The Asparaginyl Endopeptidase Legumain: An Emerging Therapeutic Target and Potential Biomarker for Alzheimer’s Disease. Int J Mol Sci 2022; 23:ijms231810223. [PMID: 36142134 PMCID: PMC9499314 DOI: 10.3390/ijms231810223] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 08/30/2022] [Accepted: 09/02/2022] [Indexed: 11/21/2022] Open
Abstract
Alzheimer’s disease (AD) is incurable dementia closely associated with aging. Most cases of AD are sporadic, and very few are inherited; the pathogenesis of sporadic AD is complex and remains to be elucidated. The asparaginyl endopeptidase (AEP) or legumain is the only recognized cysteine protease that specifically hydrolyzes peptide bonds after asparagine residues in mammals. The expression level of AEPs in healthy brains is far lower than that of peripheral organs. Recently, growing evidence has indicated that aging may upregulate and overactivate brain AEPs. The overactivation of AEPs drives the onset of AD through cleaving tau and amyloid precursor proteins (APP), and SET, an inhibitor of protein phosphatase 2A (PP2A). The AEP-mediated cleavage of these peptides enhances amyloidosis, promotes tau hyperphosphorylation, and ultimately induces neurodegeneration and cognitive impairment. Upregulated AEPs and related deleterious reactions constitute upstream events of amyloid/tau toxicity in the brain, and represent early pathological changes in AD. Thus, upregulated AEPs are an emerging drug target for disease modification and a potential biomarker for predicting preclinical AD. However, the presence of the blood–brain barrier greatly hinders establishing body-fluid-based methods to measure brain AEPs. Research on AEP-activity-based imaging probes and our recent work suggest that the live brain imaging of AEPs could be used to evaluate its predictive efficacy as an AD biomarker. To advance translational research in this area, AEP imaging probes applicable to human brain and AEP inhibitors with good druggability are urgently needed.
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10
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Clostridium novyi’s Alpha-Toxin Changes Proteome and Phosphoproteome of HEp-2 Cells. Int J Mol Sci 2022; 23:ijms23179939. [PMID: 36077344 PMCID: PMC9456407 DOI: 10.3390/ijms23179939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 08/17/2022] [Accepted: 08/27/2022] [Indexed: 11/16/2022] Open
Abstract
C. novyi type A produces the alpha-toxin (TcnA) that belongs to the large clostridial glucosylating toxins (LCGTs) and is able to modify small GTPases by N-acetylglucosamination on conserved threonine residues. In contrast, other LCGTs including Clostridioides difficile toxin A and toxin B (TcdA; TcdB) modify small GTPases by mono-o-glucosylation. Both modifications inactivate the GTPases and cause strong effects on GTPase-dependent signal transduction pathways and the consequent reorganization of the actin cytoskeleton leading to cell rounding and finally cell death. However, the effect of TcnA on target cells is largely unexplored. Therefore, we performed a comprehensive screening approach of TcnA treated HEp-2 cells and analyzed their proteome and their phosphoproteome using LC-MS-based methods. With this data-dependent acquisition (DDA) approach, 5086 proteins and 9427 phosphosites could be identified and quantified. Of these, 35 proteins were found to be significantly altered after toxin treatment, and 1832 phosphosites were responsive to TcnA treatment. By analyzing the TcnA-induced proteomic effects of HEp-2 cells, 23 common signaling pathways were identified to be altered, including Actin Cytoskeleton Signaling, Epithelial Adherens Junction Signaling, and Signaling by Rho Family GTPases. All these pathways are also regulated after application of TcdA or TcdB of C. difficile. After TcnA treatment the regulation on phosphorylation level was much stronger compared to the proteome level, in terms of both strength of regulation and the number of regulated phosphosites. Interestingly, various signaling pathways such as Signaling by Rho Family GTPases or Integrin Signaling were activated on proteome level while being inhibited on phosphorylation level or vice versa as observed for the Role of BRCA1 in DNA Damage Response. ZIP kinase, as well as Calmodulin-dependent protein kinases IV & II, were observed as activated while Aurora-A kinase and CDK kinases tended to be inhibited in cells treated with TcnA based on their substrate regulation pattern.
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Zhang D, Wang Z, Hu S, Chan NY, Liew HT, Lescar J, Tam JP, Liu CF. Asparaginyl Endopeptidase-Mediated Protein C-Terminal Hydrazinolysis for the Synthesis of Bioconjugates. Bioconjug Chem 2022; 33:238-247. [PMID: 34985285 DOI: 10.1021/acs.bioconjchem.1c00551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Asparaginyl endopeptidases (AEPs) are cysteinyl enzymes naturally catalyzing the hydrolysis and transpeptidation reactions at Asx-Xaa bonds. These reactions go by a common acyl-enzyme thioester intermediate, which is either attacked by water (for a protease-AEP) or by a peptidic amine nucleophile (for a ligase-AEP) to form the respective hydrolysis or aminolysis product. Herein, we show that hydrazine and hydroxylamine, two α-effect nucleophiles, are capable of resolving the thioester intermediate to yield peptide and protein products containing a C-terminal hydrazide and hydroxamic acid functionality, respectively. The hydrazinolysis reaction exhibits very high efficiency and can be completed in minutes at a low enzyme-to-substrate ratio. We further show the utility of the so-formed asparaginyl hydrazide in native chemical ligation and hydrazone conjugation. Using an EGFR-targeting affibody as a model protein, we have showcased our methodology in the preparation of a number of protein ligation or conjugation products, which are decorated with various functional moieties. The ZEGFR affibody-doxorubicin conjugate shows high selective binding and cytotoxicity toward the EGFR-positive A431 cells. Our results demonstrate the advantages of AEP-mediated protein hydrazinolysis as a simple and straightforward strategy for the precision manufacturing of protein bioconjugates.
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Affiliation(s)
- Dingpeng Zhang
- School of Biological Science, Nanyang Technological University, 60 Nanyang Drive, 637551 Singapore
| | - Zhen Wang
- School of Biological Science, Nanyang Technological University, 60 Nanyang Drive, 637551 Singapore
| | - Side Hu
- School of Biological Science, Nanyang Technological University, 60 Nanyang Drive, 637551 Singapore
| | - Ning-Yu Chan
- School of Biological Science, Nanyang Technological University, 60 Nanyang Drive, 637551 Singapore
| | - Heng Tai Liew
- School of Biological Science, Nanyang Technological University, 60 Nanyang Drive, 637551 Singapore
| | - Julien Lescar
- School of Biological Science, Nanyang Technological University, 60 Nanyang Drive, 637551 Singapore
| | - James P Tam
- School of Biological Science, Nanyang Technological University, 60 Nanyang Drive, 637551 Singapore
| | - Chuan-Fa Liu
- School of Biological Science, Nanyang Technological University, 60 Nanyang Drive, 637551 Singapore
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