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Richau KH, Kaschani F, Verdoes M, Pansuriya TC, Niessen S, Stüber K, Colby T, Overkleeft HS, Bogyo M, Van der Hoorn RA. Subclassification and biochemical analysis of plant papain-like cysteine proteases displays subfamily-specific characteristics. PLANT PHYSIOLOGY 2012; 158:1583-99. [PMID: 22371507 PMCID: PMC3320171 DOI: 10.1104/pp.112.194001] [Citation(s) in RCA: 126] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 02/24/2012] [Indexed: 05/18/2023]
Abstract
Papain-like cysteine proteases (PLCPs) are a large class of proteolytic enzymes associated with development, immunity, and senescence. Although many properties have been described for individual proteases, the distribution of these characteristics has not been studied collectively. Here, we analyzed 723 plant PLCPs and classify them into nine subfamilies that are present throughout the plant kingdom. Analysis of these subfamilies revealed previously unreported distinct subfamily-specific functional and structural characteristics. For example, the NPIR and KDEL localization signals are distinctive for subfamilies, and the carboxyl-terminal granulin domain occurs in two PLCP subfamilies, in which some individual members probably evolved by deletion of the granulin domains. We also discovered a conserved double cysteine in the catalytic site of SAG12-like proteases and two subfamily-specific disulfides in RD19A-like proteases. Protease activity profiling of representatives of the PLCP subfamilies using novel fluorescent probes revealed striking polymorphic labeling profiles and remarkably distinct pH dependency. Competition assays with peptide-epoxide scanning libraries revealed common and unique inhibitory fingerprints. Finally, we expand the detection of PLCPs by identifying common and organ-specific protease activities and identify previously undetected proteases upon labeling with cell-penetrating probes in vivo. This study provides the plant protease research community with tools for further functional annotation of plant PLCPs.
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Nogueira FCS, Palmisano G, Soares EL, Shah M, Soares AA, Roepstorff P, Campos FAP, Domont GB. Proteomic profile of the nucellus of castor bean (Ricinus communis L.) seeds during development. J Proteomics 2012; 75:1933-9. [PMID: 22266101 DOI: 10.1016/j.jprot.2012.01.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 12/28/2011] [Accepted: 01/04/2012] [Indexed: 11/16/2022]
Abstract
In this study, we performed a proteomic analysis of nucellus from two developmental stages of Ricinus communis seeds by a GeLC-MS/MS approach, using of a high resolution orbitrap mass spectrometer, which resulted in the identification of a total of 766 proteins that were grouped into 553 protein groups. The distribution of the identified proteins in stages III and IV into different Gene Ontology categories was similar, with a remarkable abundance of proteins associated with the protein synthesis machinery of cells, as well as several classes of proteins involved in protein degradation, particularly of peptidases associated with programmed cell death. Consistent with the role of the nucellus in mediating nutrient transfer from maternal tissues to the endosperm and embryo, a significant proportion of the identified proteins are related to amino acid metabolism, but none of the identified proteins are known to have a role as storage proteins. Moreover for the first time, ricin isoforms were identified in tissues other than seed endosperm. Results are discussed in the context of the spatial and temporal distribution of the identified proteins within the nucellar cell layers.
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Affiliation(s)
- Fábio C S Nogueira
- Proteomic Unit, Institute of Chemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
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53
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Gu C, Shabab M, Strasser R, Wolters PJ, Shindo T, Niemer M, Kaschani F, Mach L, van der Hoorn RAL. Post-translational regulation and trafficking of the granulin-containing protease RD21 of Arabidopsis thaliana. PLoS One 2012; 7:e32422. [PMID: 22396764 PMCID: PMC3292552 DOI: 10.1371/journal.pone.0032422] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Accepted: 01/26/2012] [Indexed: 12/18/2022] Open
Abstract
RD21-like proteases are ubiquitous, plant-specific papain-like proteases typified by carrying a C-terminal granulin domain. RD21-like proteases are involved in immunity and associated with senescence and various types of biotic and abiotic stresses. Here, we interrogated Arabidopsis RD21 regulation and trafficking by site-directed mutagenesis, agroinfiltration, western blotting, protease activity profiling and protein degradation. Using an introduced N-glycan sensor, deglycosylation experiments and glyco-engineered N. benthamiana plants, we show that RD21 passes through the Golgi where it becomes fucosylated. Our studies demonstrate that RD21 is regulated at three post-translational levels. Prodomain removal is not blocked in the catalytic Cys mutant, indicating that RD21 is activated by a proteolytic cascade. However, RD21 activation in Arabidopsis does not require vacuolar processing enzymes (VPEs) or aleurain-like protease AALP. In contrast, granulin domain removal requires the catalytic Cys and His residues and is therefore autocatalytic. Furthermore, SDS can (re-)activate latent RD21 in Arabidopsis leaf extracts, indicating the existence of a third layer of post-translational regulation, possibly mediated by endogenous inhibitors. RD21 causes a dominant protease activity in Arabidopsis leaf extracts, responsible for SDS-induced proteome degradation.
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Affiliation(s)
- Christian Gu
- The Plant Chemetics Lab, Chemical Genomics Centre of the Max Planck Society, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Mohammed Shabab
- The Plant Chemetics Lab, Chemical Genomics Centre of the Max Planck Society, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Richard Strasser
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Pieter J. Wolters
- The Plant Chemetics Lab, Chemical Genomics Centre of the Max Planck Society, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Takayuki Shindo
- The Plant Chemetics Lab, Chemical Genomics Centre of the Max Planck Society, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Melanie Niemer
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Farnusch Kaschani
- The Plant Chemetics Lab, Chemical Genomics Centre of the Max Planck Society, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Lukas Mach
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Renier A. L. van der Hoorn
- The Plant Chemetics Lab, Chemical Genomics Centre of the Max Planck Society, Max Planck Institute for Plant Breeding Research, Cologne, Germany
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54
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Wu MJ, McKay S, Howes N, Chin J, Hegedus E. Identification of novel serpin isoforms and serpin polymorphisms among Australian wheat cultivars. J Cereal Sci 2012. [DOI: 10.1016/j.jcs.2011.11.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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55
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Lozano-Durán R, Rosas-Díaz T, Luna AP, Bejarano ER. Identification of host genes involved in geminivirus infection using a reverse genetics approach. PLoS One 2011; 6:e22383. [PMID: 21818318 PMCID: PMC3144222 DOI: 10.1371/journal.pone.0022383] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2011] [Accepted: 06/20/2011] [Indexed: 12/17/2022] Open
Abstract
Geminiviruses, like all viruses, rely on the host cell machinery to establish a successful infection, but the identity and function of these required host proteins remain largely unknown. Tomato yellow leaf curl Sardinia virus (TYLCSV), a monopartite geminivirus, is one of the causal agents of the devastating Tomato yellow leaf curl disease (TYLCD). The transgenic 2IRGFP N. benthamiana plants, used in combination with Virus Induced Gene Silencing (VIGS), entail an important potential as a tool in reverse genetics studies to identify host factors involved in TYLCSV infection. Using these transgenic plants, we have made an accurate description of the evolution of TYLCSV replication in the host in both space and time. Moreover, we have determined that TYLCSV and Tobacco rattle virus (TRV) do not dramatically influence each other when co-infected in N. benthamiana, what makes the use of TRV-induced gene silencing in combination with TYLCSV for reverse genetic studies feasible. Finally, we have tested the effect of silencing candidate host genes on TYLCSV infection, identifying eighteen genes potentially involved in this process, fifteen of which had never been implicated in geminiviral infections before. Seven of the analyzed genes have a potential anti-viral effect, whereas the expression of the other eleven is required for a full infection. Interestingly, almost half of the genes altering TYLCSV infection play a role in postranslational modifications. Therefore, our results provide new insights into the molecular mechanisms underlying geminivirus infections, and at the same time reveal the 2IRGFP/VIGS system as a powerful tool for functional reverse genetics studies.
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Affiliation(s)
- Rosa Lozano-Durán
- Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departamento Biología Celular, Genética y Fisiología, Universidad de Málaga, Campus Teatinos, Málaga, Spain
| | - Tábata Rosas-Díaz
- Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departamento Biología Celular, Genética y Fisiología, Universidad de Málaga, Campus Teatinos, Málaga, Spain
| | - Ana P. Luna
- Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departamento Biología Celular, Genética y Fisiología, Universidad de Málaga, Campus Teatinos, Málaga, Spain
| | - Eduardo R. Bejarano
- Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departamento Biología Celular, Genética y Fisiología, Universidad de Málaga, Campus Teatinos, Málaga, Spain
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56
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Watanabe N, Lam E. Arabidopsis metacaspase 2d is a positive mediator of cell death induced during biotic and abiotic stresses. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2011; 66:969-82. [PMID: 21395887 DOI: 10.1111/j.1365-313x.2011.04554.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Cysteine proteases such as caspases play important roles in programmed cell death (PCD) of metazoans. Plant metacaspases (MCPs), a family of cysteine proteases structurally related to caspases, have been hypothesized to be ancestors of metazoan caspases, despite their different substrate specificity. Arabidopsis thaliana contains six type II MCP genes (AtMCP2a-f). Whether and how these individual members are involved in controlling PCD in plants remains largely unknown. Here we investigated the function and regulation of AtMCP2d, the predominant and constitutively expressed member of type II MCPs, in stress-inducible PCD. Two AtMCP2d mutants (mcp2d-1 and mcp2d-3) exhibited reduced sensitivity to PCD-inducing mycotoxin fumonisin B1 as well as oxidative stress inducers, whereas AtMCP2d over-expressors were more sensitive to these agents, and exhibited accelerated cell-death progression. We found that AtMCP2d exclusively localizes to the cytosol, and its accumulation and self-processing patterns were age-dependent in leaves. Importantly, active proteolytic processing of AtMCP2d proteins dependent on its catalytic activity was observed in mature leaves during mycotoxin-induced cell death. We also found that mcp2d-1 leaves exhibited reduced cell death in response to Pseudomonas syringae carrying avirulent gene avrRpt2, and that self-processing of AtMCP2d was also detected in wild-type leaves in response to this pathogen. Furthermore, increases in processed AtMCP2d proteins were found to correlate with conditional cell-death induction in two lesion-mimic mutants (cpr22 and ssi4) that exhibit spontaneous cell-death phenotypes. Taken together, our data strongly suggest that AtMCP2d plays a positive regulatory role in biotic and abiotic stress-induced PCD.
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Affiliation(s)
- Naohide Watanabe
- Department of Plant Biology and Pathology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, NJ 08901-8550, USA
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57
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Alvarez-Alfageme F, Maharramov J, Carrillo L, Vandenabeele S, Vercammen D, Van Breusegem F, Smagghe G. Potential use of a serpin from Arabidopsis for pest control. PLoS One 2011; 6:e20278. [PMID: 21655276 PMCID: PMC3104999 DOI: 10.1371/journal.pone.0020278] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Accepted: 04/25/2011] [Indexed: 12/20/2022] Open
Abstract
Although genetically modified (GM) plants expressing toxins from Bacillus thuringiensis (Bt) protect agricultural crops against lepidopteran and coleopteran pests, field-evolved resistance to Bt toxins has been reported for populations of several lepidopteran species. Moreover, some important agricultural pests, like phloem-feeding insects, are not susceptible to Bt crops. Complementary pest control strategies are therefore necessary to assure that the benefits provided by those insect-resistant transgenic plants are not compromised and to target those pests that are not susceptible. Experimental GM plants producing plant protease inhibitors have been shown to confer resistance against a wide range of agricultural pests. In this study we assessed the potential of AtSerpin1, a serpin from Arabidopsis thaliana (L). Heynh., for pest control. In vitro assays were conducted with a wide range of pests that rely mainly on either serine or cysteine proteases for digestion and also with three non-target organisms occurring in agricultural crops. AtSerpin1 inhibited proteases from all pest and non-target species assayed. Subsequently, the cotton leafworm Spodoptera littoralis Boisduval and the pea aphid Acyrthosiphon pisum (Harris) were fed on artificial diets containing AtSerpin1, and S. littoralis was also fed on transgenic Arabidopsis plants overproducing AtSerpin1. AtSerpin1 supplied in the artificial diet or by transgenic plants reduced the growth of S. littoralis larvae by 65% and 38%, respectively, relative to controls. Nymphs of A. pisum exposed to diets containing AtSerpin1 suffered high mortality levels (LC50 = 637 µg ml−1). The results indicate that AtSerpin1 is a good candidate for exploitation in pest control.
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Affiliation(s)
- Fernando Alvarez-Alfageme
- Laboratory of Agrozoology, Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Gent, Belgium
- * E-mail: (F-AA); (GS)
| | - Jafar Maharramov
- Laboratory of Agrozoology, Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Gent, Belgium
| | - Laura Carrillo
- Laboratory of Agrozoology, Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Gent, Belgium
| | - Steven Vandenabeele
- VIB Department of Plant Systems Biology, Ghent University, Gent, Belgium
- Department of Plant Biotechnology and Genetics, Ghent University, Gent, Belgium
| | - Dominique Vercammen
- VIB Department of Plant Systems Biology, Ghent University, Gent, Belgium
- Department of Plant Biotechnology and Genetics, Ghent University, Gent, Belgium
| | - Frank Van Breusegem
- VIB Department of Plant Systems Biology, Ghent University, Gent, Belgium
- Department of Plant Biotechnology and Genetics, Ghent University, Gent, Belgium
| | - Guy Smagghe
- Laboratory of Agrozoology, Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Gent, Belgium
- * E-mail: (F-AA); (GS)
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58
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Huntington JA, Whisstock JC. Molecular contortionism - on the physical limits of serpin 'loop-sheet' polymers. Biol Chem 2011; 391:973-82. [PMID: 20731544 DOI: 10.1515/bc.2010.085] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Members of the serpin (serine protease inhibitor) superfamily fold into a metastable conformation that is crucial for proper function. As a consequence, serpins are susceptible to mutations that cause misfolding and the intracellular accumulation of pathogenic polymers. The mechanism of serpin polymerisation remains to be resolved, however, over the past two decades the 'loop-sheet' hypothesis has gained wide acceptance. In this mechanism the reactive centre loop of one serpin monomer inserts into the beta-sheet A of another (in trans), in a manner similar to what is seen for reactive centre loop-cleaved and latent conformations (in cis). The hypothesis has been refined in response to certain experimental data, but it has proved difficult to assess the various propositions without creating molecular models. Here we evaluate the loop-sheet mechanism by creating models of pentamers of the archetypal serpin alpha(1)-antitrypsin. We conclude that an inescapable consequence of the loop-sheet mechanism is polymer compaction and rigidity, properties that are inconsistent with the 'beads-on-a-string' morphology of polymers obtained from human tissue. The recent crystal structure of a domain-swapped serpin dimer suggests an alternative mechanism that is consistent with known polymer properties, including the requirement of partial unfolding to induce polymer formation in vitro, and polymerisation from a folding intermediate in vivo.
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Affiliation(s)
- James A Huntington
- Department of Haematology, University of Cambridge, Cambridge Institute for Medical Research, Cambridge, UK.
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59
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Watanabe N, Lam E. Calcium-dependent activation and autolysis of Arabidopsis metacaspase 2d. J Biol Chem 2011; 286:10027-40. [PMID: 21209078 DOI: 10.1074/jbc.m110.194340] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Metacaspases (MCPs) are members of a new family of cysteine proteases found in plants, fungi, and protozoa that are structurally related to metazoan caspases. Recent studies showed that plant MCPs are arginine/lysine-specific cysteine proteases with caspase-like processing activities in vitro and in vivo, and some of the plant type II MCPs exhibit Ca(2+) dependence for their endopeptidase activity in vitro. However, the mechanisms and biological relevance of Ca(2+) dependence and self-processing of plant MCPs remains unclear. Here we show that recombinant AtMCP2d, the most abundantly expressed member of Arabidopsis type II MCPs at the transcriptional level, exhibits a strict Ca(2+) dependence for its catalytic activation that is apparently mediated by intramolecular self-cleavage mechanism. However, rapid inactivation of AtMCP2d activity concomitant with Ca(2+)-induced self-processing at multiple internal sites was observed. Because active AtMCP2d can cleave its inactive form, intermolecular cleavage (autolysis) of AtMCP2d could also occur under our assay conditions. Ca(2+)-induced self-processing of recombinant AtMCP2d was found to correlate with the sequential appearance of at least six intermediates, including self-cleaved forms, during the proenzyme purification process. Six of these peptides were characterized, and the cleavage sites were mapped through N-terminal protein sequencing. Mutation analysis of AtMCP2d revealed that cleavage after Lys-225, which is a highly conserved residue among the six Arabidopsis type II MCPs, is critical for the catalytic activation by Ca(2+), and we demonstrate that this residue is essential for AtMCP2d activation of H(2)O(2)-induced cell death in yeast. Together, our results provide clues to understand the mode of regulation for this class of proteases.
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Affiliation(s)
- Naohide Watanabe
- Department of Plant Biology and Pathology, Rutgers University, New Brunswick, New Jersey 08901-8550, USA
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60
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van der Hoorn RAL, Colby T, Nickel S, Richau KH, Schmidt J, Kaiser M. Mining the Active Proteome of Arabidopsis thaliana. FRONTIERS IN PLANT SCIENCE 2011; 2:89. [PMID: 22639616 PMCID: PMC3355598 DOI: 10.3389/fpls.2011.00089] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Accepted: 11/08/2011] [Indexed: 05/20/2023]
Abstract
Assigning functions to the >30,000 proteins encoded by the Arabidopsis genome is a challenging task of the Arabidopsis Functional Genomics Network. Although genome-wide technologies like proteomics and transcriptomics have generated a wealth of information that significantly accelerated gene annotation, protein activities are poorly predicted by transcript or protein levels as protein activities are post-translationally regulated. To directly display protein activities in Arabidopsis proteomes, we developed and applied activity-based protein profiling (ABPP). ABPP is based on the use of small molecule probes that react with the catalytic residues of distinct protein classes in an activity-dependent manner. Labeled proteins are separated and detected from proteins gels and purified and identified by mass spectrometry. Using probes of six different chemotypes we have displayed activities of 76 Arabidopsis proteins. These proteins represent over 10 different protein classes that contain over 250 Arabidopsis proteins, including cysteine, serine, and metalloproteases, lipases, acyltransferases, and the proteasome. We have developed methods for identification of in vivo labeled proteins using click chemistry and for in vivo imaging with fluorescent probes. In vivo labeling has revealed additional protein activities and unexpected subcellular activities of the proteasome. Labeling of extracts displayed several differential activities, e.g., of the proteasome during immune response and methylesterases during infection. These studies illustrate the power of ABPP to display the functional proteome and testify to a successful interdisciplinary collaboration involving chemical biology, organic chemistry, and proteomics.
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Affiliation(s)
- Renier A. L. van der Hoorn
- Plant Chemetics Lab, Chemical Genomics Centre of the Max Planck Society, Max Planck Institute for Plant Breeding ResearchCologne, Germany
- *Correspondence: Renier A. L. van der Hoorn, Plant Chemetics Lab, Chemical Genomics Centre of the Max Planck Society, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany. e-mail:
| | - Tom Colby
- Proteomics Service Unit, Max Planck Institute for Plant Breeding ResearchCologne, Germany
| | - Sabrina Nickel
- Fakultät für Biologie, Chemische Biologie, Zentrum für Medizinische Biotechnologie, University of Duisburg-EssenEssen, Germany
| | - Kerstin H. Richau
- Plant Chemetics Lab, Chemical Genomics Centre of the Max Planck Society, Max Planck Institute for Plant Breeding ResearchCologne, Germany
| | - Jürgen Schmidt
- Proteomics Service Unit, Max Planck Institute for Plant Breeding ResearchCologne, Germany
| | - Markus Kaiser
- Fakultät für Biologie, Chemische Biologie, Zentrum für Medizinische Biotechnologie, University of Duisburg-EssenEssen, Germany
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62
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Silverman GA, Whisstock JC, Bottomley SP, Huntington JA, Kaiserman D, Luke CJ, Pak SC, Reichhart JM, Bird PI. Serpins flex their muscle: I. Putting the clamps on proteolysis in diverse biological systems. J Biol Chem 2010; 285:24299-305. [PMID: 20498369 DOI: 10.1074/jbc.r110.112771] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Serpins compose the largest superfamily of peptidase inhibitors and are well known as regulators of hemostasis and thrombolysis. Studies using model organisms, from plants to vertebrates, now show that serpins and their unique inhibitory mechanism and conformational flexibility are exploited to control proteolysis in molecular pathways associated with cell survival, development, and host defense. In addition, an increasing number of non-inhibitory serpins are emerging as important elements within a diversity of biological systems by serving as chaperones, hormone transporters, or anti-angiogenic factors.
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Affiliation(s)
- Gary A Silverman
- Department of Pediatrics and Cell Biology and Physiology, Children's Hospital of Pittsburgh and Magee-Womens Hospital, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15201, USA.
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