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Dupuis JH, Wang S, Song C, Yada RY. The role of disulfide bonds in a Solanum tuberosum saposin-like protein investigated using molecular dynamics. PLoS One 2020; 15:e0237884. [PMID: 32841243 PMCID: PMC7447066 DOI: 10.1371/journal.pone.0237884] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 08/04/2020] [Indexed: 01/31/2023] Open
Abstract
The Solanum tuberosum plant specific insert (StPSI) has a defensive role in potato plants, with the requirements of acidic pH and anionic lipids. The StPSI contains a set of three highly conserved disulfide bonds that bridge the protein’s helical domains. Removal of these bonds leads to enhanced membrane interactions. This work examined the effects of their sequential removal, both individually and in combination, using all-atom molecular dynamics to elucidate the role of disulfide linkages in maintaining overall protein tertiary structure. The tertiary structure was found to remain stable at both acidic (active) and neutral (inactive) pH despite the removal of disulfide linkages. The findings include how the dimer structure is stabilized and the impact on secondary structure on a residue-basis as a function of disulfide bond removal. The StPSI possesses an extensive network of inter-monomer hydrophobic interactions and intra-monomer hydrogen bonds, which is likely the key to the stability of the StPSI by stabilizing local secondary structure and the tertiary saposin-fold, leading to a robust association between monomers, regardless of the disulfide bond state. Removal of disulfide bonds did not significantly impact secondary structure, nor lead to quaternary structural changes. Instead, disulfide bond removal induces regions of amino acids with relatively higher or lower variation in secondary structure, relative to when all the disulfide bonds are intact. Although disulfide bonds are not required to preserve overall secondary structure, they may have an important role in maintaining a less plastic structure within plant cells in order to regulate membrane affinity or targeting.
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Affiliation(s)
- John H. Dupuis
- Food, Nutrition, and Health Program, Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada
| | - Shenlin Wang
- College of Chemistry and Molecular Engineering and Beijing NMR Center, Peking University, Beijing, People's Republic of China
| | - Chen Song
- Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, People’s Republic of China
| | - Rickey Y. Yada
- Food, Nutrition, and Health Program, Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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2
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Cheung LKY, Dupuis JH, Dee DR, Bryksa BC, Yada RY. Roles of Plant-Specific Inserts in Plant Defense. TRENDS IN PLANT SCIENCE 2020; 25:682-694. [PMID: 32526173 DOI: 10.1016/j.tplants.2020.02.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 02/10/2020] [Accepted: 02/14/2020] [Indexed: 06/11/2023]
Abstract
Ubiquitously expressed in plants, the plant-specific insert (PSI) of typical plant aspartic proteases (tpAPs) has been associated with plant development, stress response, and defense processes against invading pathogens. Despite sharing high sequence identity, structural studies revealed possible different mechanisms of action among species. The PSI induces signaling pathways of defense hormones in vivo and demonstrates broad-spectrum activity against phytopathogens in vitro. Recent characterization of the PSI-tpAP relationship uncovered novel, nonconventional intracellular protein transport pathways and improved tpAP production yields for industrial applications. In spite of research to date, relatively little is known about the structure-function relationships of PSIs. A comprehensive understanding of their biological roles may benefit plant protection strategies against virulent phytopathogens.
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Affiliation(s)
- Lennie K Y Cheung
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - John H Dupuis
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Derek R Dee
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Brian C Bryksa
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Rickey Y Yada
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC V6T 1Z4, Canada. @ubc.ca
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Hoernstein SNW, Fode B, Wiedemann G, Lang D, Niederkrüger H, Berg B, Schaaf A, Frischmuth T, Schlosser A, Decker EL, Reski R. Host Cell Proteome of Physcomitrella patens Harbors Proteases and Protease Inhibitors under Bioproduction Conditions. J Proteome Res 2018; 17:3749-3760. [PMID: 30226384 DOI: 10.1021/acs.jproteome.8b00423] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Host cell proteins are inevitable contaminants of biopharmaceuticals. Here, we performed detailed analyses of the host cell proteome of moss ( Physcomitrella patens) bioreactor supernatants using mass spectrometry and subsequent bioinformatics analysis. Distinguishing between the apparent secretome and intracellular contaminants, a complex extracellular proteolytic network including subtilisin-like proteases, metallo-proteases, and aspartic proteases was identified. Knockout of a subtilisin-like protease affected the overall extracellular proteolytic activity. Besides proteases, also secreted protease-inhibiting proteins such as serpins were identified. Further, we confirmed predicted cleavage sites of 40 endogenous signal peptides employing an N-terminomics approach. The present data provide novel aspects to optimize both product stability of recombinant biopharmaceuticals as well as their maturation along the secretory pathway. Data are available via ProteomeXchange with identifier PXD009517.
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Affiliation(s)
- Sebastian N W Hoernstein
- Plant Biotechnology, Faculty of Biology , University of Freiburg , Schaenzlestrasse 1 , D-79104 Freiburg , Germany
| | - Benjamin Fode
- Greenovation Biotech GmbH , Hans-Bunte-Strasse 19 , D-79108 Freiburg , Germany
| | - Gertrud Wiedemann
- Plant Biotechnology, Faculty of Biology , University of Freiburg , Schaenzlestrasse 1 , D-79104 Freiburg , Germany
| | - Daniel Lang
- Plant Biotechnology, Faculty of Biology , University of Freiburg , Schaenzlestrasse 1 , D-79104 Freiburg , Germany.,Plant Genome and System Biology , Helmholtz Center Munich , D-85764 Neuherberg , Germany
| | - Holger Niederkrüger
- Greenovation Biotech GmbH , Hans-Bunte-Strasse 19 , D-79108 Freiburg , Germany
| | - Birgit Berg
- Greenovation Biotech GmbH , Hans-Bunte-Strasse 19 , D-79108 Freiburg , Germany
| | - Andreas Schaaf
- Greenovation Biotech GmbH , Hans-Bunte-Strasse 19 , D-79108 Freiburg , Germany
| | - Thomas Frischmuth
- Greenovation Biotech GmbH , Hans-Bunte-Strasse 19 , D-79108 Freiburg , Germany
| | - Andreas Schlosser
- Rudolf-Virchow-Center for Experimental Biomedicine , University of Wuerzburg , D-97080 Wuerzburg , Germany
| | - Eva L Decker
- Plant Biotechnology, Faculty of Biology , University of Freiburg , Schaenzlestrasse 1 , D-79104 Freiburg , Germany
| | - Ralf Reski
- Plant Biotechnology, Faculty of Biology , University of Freiburg , Schaenzlestrasse 1 , D-79104 Freiburg , Germany.,BIOSS - Centre for Biological Signalling Studies , University of Freiburg , D-79104 Freiburg , Germany
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pH dependent membrane binding of the Solanum tuberosum plant specific insert: An in silico study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:2608-2618. [PMID: 30291921 DOI: 10.1016/j.bbamem.2018.10.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 09/27/2018] [Accepted: 10/01/2018] [Indexed: 01/07/2023]
Abstract
The Solanum tuberosum plant-specific insert (StPSI) has been shown to possess potent antimicrobial activity against both human and plant pathogens. Furthermore, in vitro, the StPSI is capable of fusing phospholipid vesicles, provided the conditions of net anionic vesicle charge and acidic pH are met. Constant pH replica-exchange simulations indicate several acidic residues on the dimer have highly perturbed pKas (<3.0; E15, D28, E85 & E100) due to involvement in salt bridges. After setting the pH of the system to either 3.0 or 7.4, all-atom simulations provided details of the effect of pH on secondary structural elements, particularly in the previously unresolved crystallographic structure of the loop section. Coarse-grained dimer-bilayer simulations demonstrated that at pH 7.4, the dimer had no affinity for neutral or anionic membranes over the course of 1 μs simulations. Conversely, at pH 3.0 two binding modes were observed. Mode 1 is mediated primarily via strong N-terminal interactions on one monomer only, whereas in mode 2, N- and C-terminal residues of one monomer and numerous polar and basic residues on the second monomer, particularly in the third helix, participate in membrane interactions. Mode 2 was accompanied by re-orientation of the dimer to a more vertical position with respect to helices 1 and 4, positioning the dimer for membrane interactions. These results offer the first examination at near-atomic resolution of residues mediating the StPSI-membrane interactions, and allow for the postulation of a possible fusion mechanism.
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Díaz ME, Rocha GF, Kise F, Rosso AM, Guevara MG, Parisi MG. Antimicrobial activity of an aspartic protease from Salpichroa origanifolia fruits. Lett Appl Microbiol 2018; 67:168-174. [PMID: 29740840 DOI: 10.1111/lam.13006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 04/09/2018] [Accepted: 04/24/2018] [Indexed: 02/03/2023]
Abstract
Plant proteases play a fundamental role in several processes like growth, development and in response to biotic and abiotic stress. In particular, aspartic proteases (AP) are expressed in different plant organs and have antimicrobial activity. Previously, we purified an AP from Salpichroa origanifolia fruits called salpichroin. The aim of this work was to determine the cytotoxic activity of this enzyme on selected plant and human pathogens. For this purpose, the growth of the selected pathogens was analysed after exposure to different concentrations of salpichroin. The results showed that the enzyme was capable of inhibiting Fusarium solani and Staphylococcus aureus in a dose-dependent manner. It was determined that 1·2 μmol l-1 of salpichroin was necessary to inhibit 50% of conidial germination, and the minimal bactericidal concentration was between 1·9 and 2·5 μmol l-1 . Using SYTOX Green dye we were able to demonstrate that salpichroin cause membrane permeabilization. Moreover, the enzyme treated with its specific inhibitor pepstatin A did not lose its antibacterial activity. This finding demonstrates that the cytotoxic activity of salpichroin is due to the alteration of the cell plasma membrane barrier but not due to its proteolytic activity. Antimicrobial activity of the AP could represent a potential alternative for the control of pathogens that affect humans or crops of economic interest. SIGNIFICANCE AND IMPACT OF THE STUDY This study provides insights into the antimicrobial activity of an aspartic protease isolated from Salpichroa origanifolia fruits on plant and human pathogens. The proteinase inhibited Fusarium solani and Staphylococcus aureus in a dose-dependent manner due to the alteration of the cell plasma membrane barrier but not due to its proteolytic activity. Antimicrobial activity of salpichroin suggests its potential applications as an important tool for the control of pathogenic micro-organisms affecting humans and crops of economic interest. Therefore, it would represent a new alternative to avoid the problems of environmental pollution and antimicrobial resistance.
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Affiliation(s)
- M E Díaz
- Departamento de Ciencias Básicas, Universidad Nacional de Luján, Luján, Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Tecnológicas, CONICET, Buenos Aires, Argentina
| | - G F Rocha
- Departamento de Ciencias Básicas, Universidad Nacional de Luján, Luján, Buenos Aires, Argentina
| | - F Kise
- Departamento de Ciencias Básicas, Universidad Nacional de Luján, Luján, Buenos Aires, Argentina
| | - A M Rosso
- Departamento de Ciencias Básicas, Universidad Nacional de Luján, Luján, Buenos Aires, Argentina
| | - M G Guevara
- Consejo Nacional de Investigaciones Científicas y Tecnológicas, CONICET, Buenos Aires, Argentina.,Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Mar del Plata, Buenos Aires, Argentina
| | - M G Parisi
- Departamento de Ciencias Básicas, Universidad Nacional de Luján, Luján, Buenos Aires, Argentina
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Frey ME, D'Ippolito S, Pepe A, Daleo GR, Guevara MG. Transgenic expression of plant-specific insert of potato aspartic proteases (StAP-PSI) confers enhanced resistance to Botrytis cinerea in Arabidopsis thaliana. PHYTOCHEMISTRY 2018; 149:1-11. [PMID: 29428248 DOI: 10.1016/j.phytochem.2018.02.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 02/01/2018] [Accepted: 02/03/2018] [Indexed: 05/20/2023]
Abstract
The plant-specific insert of Solanum tuberosum aspartic proteases (StAP-PSI) has high structural similarity with NK-lysin and granulysin, two saposin-like proteins (SAPLIPs) with antimicrobial activity. Recombinant StAP-PSI and some SAPLIPs show antimicrobial activity against pathogens that affect human and plants. In this work, we transformed Arabidopsis thaliana plants with StAP-PSI encoding sequence with its corresponding signal peptide under the control of the cauliflower mosaic virus (CaMV) 35S promoter. Results obtained show that StAP-PSI significantly enhances Arabidopsis resistance against Botrytis cinerea infection. StAP-PSI is secreted into the leaf apoplast and acts directly against pathogens; thereby complementing plant innate immune responses. Data obtained from real-time PCR assays show that the constitutive expression of StAP-PSI induces the expression of genes that regulate jasmonic acid signalling pathway, such as PDF1.2, in response to infection due to necrotrophic pathogens. On the other hand, according to the data described for other antimicrobial peptides, the presence of the StAP-PSI protein in the apoplast of A. thaliana leaves is responsible for the expression of salicylic acid-associated genes, such as PR-1, irrespective of infection with B. cinerea. These results indicate that the increased resistance demonstrated by A. thaliana plants that constitutively express StAP-PSI owing to B. cinerea infection compared to the wild-type plants is a consequence of two factors, i.e., the antifungal activity of StAP-PSI and the overexpression of A. thaliana defense genes induced by the constitutive expression of StAP-PSI. We suggest that the use of this protein would help in minimizing the ecological and health risks that arise from the use of pesticides. We suggest that the use of this protein would help in minimizing the ecological and health risks that arise from the spreading of resistance of agriculturally important pathogens.
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Affiliation(s)
- María Eugenia Frey
- Biological Research Institute, National Council of Scientific and Technique Research (CONICET), University of Mar del Plata, Mar del Plata (UNMDP), Argentina
| | - Sebastián D'Ippolito
- Biological Research Institute, National Council of Scientific and Technique Research (CONICET), University of Mar del Plata, Mar del Plata (UNMDP), Argentina
| | - Alfonso Pepe
- Biological Research Institute, National Council of Scientific and Technique Research (CONICET), University of Mar del Plata, Mar del Plata (UNMDP), Argentina
| | - Gustavo Raúl Daleo
- Biological Research Institute, National Council of Scientific and Technique Research (CONICET), University of Mar del Plata, Mar del Plata (UNMDP), Argentina
| | - María Gabriela Guevara
- Biological Research Institute, National Council of Scientific and Technique Research (CONICET), University of Mar del Plata, Mar del Plata (UNMDP), Argentina.
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Bryksa BC, Yada RY. Protein Structure Insights into the Bilayer Interactions of the Saposin-Like Domain of Solanum tuberosum Aspartic Protease. Sci Rep 2017; 7:16911. [PMID: 29208977 PMCID: PMC5717070 DOI: 10.1038/s41598-017-16734-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 11/16/2017] [Indexed: 12/26/2022] Open
Abstract
Many plant aspartic proteases contain a saposin-like domain whose principal functions are intracellular sorting and host defence. Its structure is characterised by helical segments cross-linked by three highly conserved cystines. The present study on the saposin-like domain of Solanum tuberosum aspartic protease revealed that acidification from inactive to active conditions causes dimerisation and a strand-to-helix secondary structure transition independent of bilayer interaction. Bilayer fusion was shown to occur under reducing conditions yielding a faster shift to larger vesicle sizes relative to native conditions, implying that a lower level structural motif might be bilayer-active. Characterisation of peptide sequences based on the domain’s secondary structural regions showed helix-3 to be active (~4% of the full domain’s activity), and mutation of its sole positively charged residue resulted in loss of activity and disordering of structure. Also, the peptides’ respective circular dichroism spectra suggested that native folding within the full domain is dependent on surrounding structure. Overall, the present study reveals that the aspartic protease saposin-like domain active structure is an open saposin fold dimer whose formation is pH-dependent, and that a bilayer-active motif shared among non-saposin membrane-active proteins including certain plant defence proteins is nested within an overall structure essential for native functionality.
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Affiliation(s)
- Brian C Bryksa
- Ontario Agricultural College, University of Guelph, N1G 2W1, Guelph, Ontario, Canada
| | - Rickey Y Yada
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, V6T 1Z4, British Columbia, Canada.
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