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van Leeuwe TM, Arentshorst M, Forn-Cuní G, Geoffrion N, Tsang A, Delvigne F, Meijer AH, Ram AFJ, Punt PJ. Deletion of the Aspergillus niger Pro-Protein Processing Protease Gene kexB Results in a pH-Dependent Morphological Transition during Submerged Cultivations and Increases Cell Wall Chitin Content. Microorganisms 2020; 8:E1918. [PMID: 33276589 PMCID: PMC7761569 DOI: 10.3390/microorganisms8121918] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 11/30/2020] [Accepted: 11/30/2020] [Indexed: 11/23/2022] Open
Abstract
There is a growing interest in the use of post-fermentation mycelial waste to obtain cell wall chitin as an added-value product. In the pursuit to identify suitable production strains that can be used for post-fermentation cell wall harvesting, we turned to an Aspergillus niger strain in which the kexB gene was deleted. Previous work has shown that the deletion of kexB causes hyper-branching and thicker cell walls, traits that may be beneficial for the reduction in fermentation viscosity and lysis. Hyper-branching of ∆kexB was previously found to be pH-dependent on solid medium at pH 6.0, but was absent at pH 5.0. This phenotype was reported to be less pronounced during submerged growth. Here, we show a series of controlled batch cultivations at a pH range of 5, 5.5, and 6 to examine the pellet phenotype of ΔkexB in liquid medium. Morphological analysis showed that ΔkexB formed wild type-like pellets at pH 5.0, whereas the hyper-branching ΔkexB phenotype was found at pH 6.0. The transition of phenotypic plasticity was found in cultivations at pH 5.5, seen as an intermediate phenotype. Analyzing the cell walls of ΔkexB from these controlled pH-conditions showed an increase in chitin content compared to the wild type across all three pH values. Surprisingly, the increase in chitin content was found to be irrespective of the hyper-branching morphology. Evidence for alterations in cell wall make-up are corroborated by transcriptional analysis that showed a significant cell wall stress response in addition to the upregulation of genes encoding other unrelated cell wall biosynthetic genes.
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Affiliation(s)
- Tim M. van Leeuwe
- Institute of Biology Leiden, Microbial Sciences, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands; (T.M.v.L.); (M.A.); (P.J.P.)
| | - Mark Arentshorst
- Institute of Biology Leiden, Microbial Sciences, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands; (T.M.v.L.); (M.A.); (P.J.P.)
| | - Gabriel Forn-Cuní
- Institute of Biology Leiden, Animal Sciences, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands; (G.F.-C.); (A.H.M.)
| | - Nicholas Geoffrion
- Centre for Structural and Functional Genomics, Concordia University, Montreal, QC H4B1R6, Canada; (N.G.); (A.T.)
| | - Adrian Tsang
- Centre for Structural and Functional Genomics, Concordia University, Montreal, QC H4B1R6, Canada; (N.G.); (A.T.)
| | - Frank Delvigne
- TERRA Teaching and Research Centre, Gembloux Agro-Bio Tech, University of Liège, Avenue de la Faculté, 2B, 5030 Gembloux, Belgium;
| | - Annemarie H. Meijer
- Institute of Biology Leiden, Animal Sciences, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands; (G.F.-C.); (A.H.M.)
| | - Arthur F. J. Ram
- Institute of Biology Leiden, Microbial Sciences, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands; (T.M.v.L.); (M.A.); (P.J.P.)
| | - Peter J. Punt
- Institute of Biology Leiden, Microbial Sciences, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands; (T.M.v.L.); (M.A.); (P.J.P.)
- Dutch DNA Biotech, Hugo R Kruytgebouw 4-Noord, Padualaan 8, 3584 CH Utrecht, The Netherlands
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2
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Propeptide genesis by Kex2-dependent cleavage of yeast wall protein 1 (Ywp1) of Candida albicans. PLoS One 2018; 13:e0207955. [PMID: 30475911 PMCID: PMC6258133 DOI: 10.1371/journal.pone.0207955] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 11/08/2018] [Indexed: 02/01/2023] Open
Abstract
Candida albicans is a prevalent fungal resident and opportunistic pathogen of humans, exhibiting a variety of ovoid and filamentous morphologies. Anchored within the cell wall of the ovoid yeast form of C. albicans is an abundant glycoprotein termed yeast wall protein 1 (Ywp1). Ywp1 has an antiadhesive effect that may facilitate yeast cell dispersal; it also contributes to the masking of the glucan matrix of the yeast cell wall, potentially providing shielding from recognition by the human immune system. Mature Ywp1 consists of an O-glycosylated core of 378 amino acids associated with an N-glycosylated propeptide that originates from an N-terminal segment of Ywp1. A tribasic (-RRR-) sequence in the immature Ywp1 polypeptide is separated by 8 amino acids from a dibasic (-KR-) sequence that is a canonical site for cleavage by the intracellular endopeptidase Kex2, and cleavage occurs at both of these sites to generate an 11 kilodalton (kDa) propeptide that remains strongly associated with the mature core of Ywp1. Previous studies demonstrated an absence of the 11 kDa propeptide in strains lacking Kex2, but the presence of lesser amounts of a 12 kDa propeptide ostensibly (and paradoxically) arising from cleavage at the dibasic site. Subsequent studies of wild type strains, however, suggested that post-secretion cleavages were carried out in vitro by acid proteases in unbuffered cultures to generate the 12 kDa propeptide. Here, intact and Gfp-tagged Ywp1 are utilized to show that neither of the two multibasic sites is normally cleaved in the absence of Kex2, but that uncleaved Ywp1 is still N-glycosylated and subsequently anchored to the cell wall. This furthers our understanding of the multistep cleavage of this highly conserved sequence, as well as the possible contributions of the cleaved propeptide to the maturation and functioning of Ywp1.
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3
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Richardson JP, Mogavero S, Moyes DL, Blagojevic M, Krüger T, Verma AH, Coleman BM, De La Cruz Diaz J, Schulz D, Ponde NO, Carrano G, Kniemeyer O, Wilson D, Bader O, Enoiu SI, Ho J, Kichik N, Gaffen SL, Hube B, Naglik JR. Processing of Candida albicans Ece1p Is Critical for Candidalysin Maturation and Fungal Virulence. mBio 2018; 9:e02178-17. [PMID: 29362237 PMCID: PMC5784256 DOI: 10.1128/mbio.02178-17] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 12/11/2017] [Indexed: 02/06/2023] Open
Abstract
Candida albicans is an opportunistic fungal pathogen responsible for superficial and life-threatening infections in humans. During mucosal infection, C. albicans undergoes a morphological transition from yeast to invasive filamentous hyphae that secrete candidalysin, a 31-amino-acid peptide toxin required for virulence. Candidalysin damages epithelial cell plasma membranes and stimulates the activating protein 1 (AP-1) transcription factor c-Fos (via p38-mitogen-activated protein kinase [MAPK]), and the MAPK phosphatase MKP1 (via extracellular signal-regulated kinases 1 and 2 [ERK1/2]-MAPK), which trigger and regulate proinflammatory cytokine responses, respectively. The candidalysin toxin resides as a discrete cryptic sequence within a larger 271-amino-acid parental preproprotein, Ece1p. Here, we demonstrate that kexin-like proteinases, but not secreted aspartyl proteinases, initiate a two-step posttranslational processing of Ece1p to produce candidalysin. Kex2p-mediated proteolysis of Ece1p after Arg61 and Arg93, but not after other processing sites within Ece1p, is required to generate immature candidalysin from Ece1p, followed by Kex1p-mediated removal of a carboxyl arginine residue to generate mature candidalysin. C. albicans strains harboring mutations of Arg61 and/or Arg93 did not secrete candidalysin, were unable to induce epithelial damage and inflammatory responses in vitro, and showed attenuated virulence in vivo in a murine model of oropharyngeal candidiasis. These observations identify enzymatic processing of C. albicans Ece1p by kexin-like proteinases as crucial steps required for candidalysin production and fungal pathogenicity.IMPORTANCECandida albicans is an opportunistic fungal pathogen that causes mucosal infection in millions of individuals worldwide. Successful infection requires the secretion of candidalysin, the first cytolytic peptide toxin identified in any human fungal pathogen. Candidalysin is derived from its parent protein Ece1p. Here, we identify two key amino acids within Ece1p vital for processing and production of candidalysin. Mutations of these residues render C. albicans incapable of causing epithelial damage and markedly reduce mucosal infection in vivo Importantly, candidalysin production requires two individual enzymatic events. The first involves processing of Ece1p by Kex2p, yielding immature candidalysin, which is then further processed by Kex1p to produce the mature toxin. These observations identify important steps for C. albicans pathogenicity at mucosal surfaces.
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Affiliation(s)
- Jonathan P Richardson
- Mucosal and Salivary Biology Division, Dental Institute, King's College London, London, United Kingdom
| | - Selene Mogavero
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knoell Institute (HKI), Jena, Germany
| | - David L Moyes
- Centre for Host-Microbiome Interactions, Mucosal and Salivary Biology Division, Dental Institute, King's College London, London, United Kingdom
| | - Mariana Blagojevic
- Mucosal and Salivary Biology Division, Dental Institute, King's College London, London, United Kingdom
| | - Thomas Krüger
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knoell Institute (HKI), Jena, Germany
| | - Akash H Verma
- Division of Rheumatology and Clinical Immunology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Bianca M Coleman
- Division of Rheumatology and Clinical Immunology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Jacinto De La Cruz Diaz
- Division of Rheumatology and Clinical Immunology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Daniela Schulz
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knoell Institute (HKI), Jena, Germany
| | - Nicole O Ponde
- Mucosal and Salivary Biology Division, Dental Institute, King's College London, London, United Kingdom
| | - Giulia Carrano
- Mucosal and Salivary Biology Division, Dental Institute, King's College London, London, United Kingdom
| | - Olaf Kniemeyer
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knoell Institute (HKI), Jena, Germany
| | - Duncan Wilson
- Medical Research Council Centre for Medical Mycology at the University of Aberdeen, Aberdeen Fungal Group, Institute of Medical Sciences, Foresterhill, Aberdeen, United Kingdom
| | - Oliver Bader
- Institute for Medical Microbiology, University Medical Center Göttingen, Göttingen, Germany
| | - Simona I Enoiu
- Mucosal and Salivary Biology Division, Dental Institute, King's College London, London, United Kingdom
| | - Jemima Ho
- Mucosal and Salivary Biology Division, Dental Institute, King's College London, London, United Kingdom
| | - Nessim Kichik
- Mucosal and Salivary Biology Division, Dental Institute, King's College London, London, United Kingdom
| | - Sarah L Gaffen
- Division of Rheumatology and Clinical Immunology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Bernhard Hube
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knoell Institute (HKI), Jena, Germany
- Friedrich Schiller University, Jena, Germany
| | - Julian R Naglik
- Mucosal and Salivary Biology Division, Dental Institute, King's College London, London, United Kingdom
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4
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Nagano N, Umemura M, Izumikawa M, Kawano J, Ishii T, Kikuchi M, Tomii K, Kumagai T, Yoshimi A, Machida M, Abe K, Shin-ya K, Asai K. Class of cyclic ribosomal peptide synthetic genes in filamentous fungi. Fungal Genet Biol 2016; 86:58-70. [DOI: 10.1016/j.fgb.2015.12.010] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 11/10/2015] [Accepted: 12/14/2015] [Indexed: 01/24/2023]
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5
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Eilert E, Rolf T, Heumaier A, Hollenberg CP, Piontek M, Suckow M. Improved processing of secretory proteins in Hansenula polymorpha by sequence variation near the processing site of the alpha mating factor prepro sequence. J Biotechnol 2013; 167:94-100. [DOI: 10.1016/j.jbiotec.2012.08.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 08/27/2012] [Accepted: 08/31/2012] [Indexed: 10/27/2022]
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6
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Serine-type carboxypeptidase KexA of Aspergillus oryzae has broader substrate specificity than Saccharomyces cerevisiae Kex1 and is required for normal hyphal growth and conidiation. Appl Environ Microbiol 2012; 78:8154-7. [PMID: 22961905 DOI: 10.1128/aem.01601-12] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Aspergillus oryzae has an ortholog of Saccharomyces cerevisiae KEX1, termed kexA. A truncated form of KexA protein showed serine-type carboxypeptidase activity and somewhat broader substrate specificity than Kex1 protease. Furthermore, our results indicated that KexA is required for normal growth of A. oryzae and that it might be involved in hyphal branching.
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7
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Jones SK, Bennett RJ. Fungal mating pheromones: choreographing the dating game. Fungal Genet Biol 2011; 48:668-76. [PMID: 21496492 PMCID: PMC3100450 DOI: 10.1016/j.fgb.2011.04.001] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2010] [Revised: 02/23/2011] [Accepted: 04/05/2011] [Indexed: 01/11/2023]
Abstract
Pheromones are ubiquitous from bacteria to mammals - a testament to their importance in regulating inter-cellular communication. In fungal species, they play a critical role in choreographing interactions between mating partners during the program of sexual reproduction. Here, we describe how fungal pheromones are synthesized, their interactions with G protein-coupled receptors, and the signals propagated by this interaction, using Saccharomyces cerevisiae as a reference point. Divergence from this model system is compared amongst the ascomycetes and basidiomycetes, which reveals the wealth of information that has been gleaned from studying pheromone-driven processes across a wide spectrum of the fungal kingdom.
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Affiliation(s)
- Stephen K. Jones
- Graduate Program in Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, RI 02912
| | - Richard J. Bennett
- Graduate Program in Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, RI 02912
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02912
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8
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Ni Z, Zhou X, Sun X, Wang Y, Zhang Y. Decrease of hirudin degradation by deleting theKEX1 gene in recombinantPichia pastoris. Yeast 2008; 25:1-8. [DOI: 10.1002/yea.1542] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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9
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Yield improvement of heterologous peptides expressed in yps1-disrupted Saccharomyces cerevisiae strains. Enzyme Microb Technol 2000; 26:671-677. [PMID: 10862872 DOI: 10.1016/s0141-0229(00)00158-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Heterologous protein expression levels in Saccharomyces cerevisiae fermentations are highly dependent on the susceptibility to endogenous yeast proteases. Small peptides, such as glucagon and glucagon-like-peptides (GLP-1 and GLP-2), featuring an open structure are particularly accessible for proteolytic degradation during fermentation. Therefore, homogeneous products cannot be obtained. The most sensitive residues are found at basic amino acid residues in the peptide sequence. These heterologous peptides are degraded mainly by the YPS1-encoded aspartic protease, yapsin1, when produced in the yeast. In this article, distinct degradation products were analyzed by HPLC and mass spectrometry, and high yield of the heterologous peptide production has been achieved by the disruption of the YPS1 gene (previously called YAP3). By this technique, high yield continuous fermentation of glucagon in S. cerevisiae is now possible.
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10
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Affiliation(s)
- R B Wickner
- Section on Genetics of Simple Eukaryotes, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892-0830, USA.
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11
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Heim J, Takabayashi K, Meyhack B, Märki W, Pohlig G. C-terminal proteolytic degradation of recombinant desulfato-hirudin and its mutants in the yeast Saccharomyces cerevisiae. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 226:341-53. [PMID: 8001551 DOI: 10.1111/j.1432-1033.1994.tb20058.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The potent thrombin inhibitor hirudin variant 1, originally isolated from the leech Hirudo medicinalis, was expressed in Saccharomyces cerevisiae under the control of a truncated glyceraldehyde-3-phosphate dehydrogenase (GAP) promoter fragment. Fusion of the yeast acid phosphatase (PHO5) signal sequence to the hirudin gene led to quantitative secretion of recombinant desulfato-hirudin variant 1 (r-hirudin) into the extracellular medium in a growth-dependent manner. In comparison to the genuine molecule, r-hirudin lacks the sulfate group at the Tyr in position 63. Besides the full-length protein of 65 amino acids (hir65), chemical analysis revealed the presence mainly of two derivatives lacking the last amino acid Gln (hir64) or the penultimate Leu (hir63) in addition. When expressing r-hirudin in mutant strains defective in all but one of the three major known carboxypeptidases, it turned out that the vacuolar carboxypeptidase yscY as well as the alpha-factor precursor-processing carboxypeptidase, ysc alpha, participate in the C-terminal degradation of r-hirudin. Direct involvement of yscY and ysc alpha was confirmed by sequential disruption of their structural genes PRC1 and KEX1, respectively. Disruption of PRA1, coding for the yscY-processing proteinase yscA, also abolished yscY-mediated C-terminal r-hirudin degradation, but clearly reduced the overall expression yield. Since ysc alpha is described to be highly specific for basic amino acids which are not present at the C-terminus of r-hirudin, a series of r-hirudin mutants with changes in the C-terminal amino acids were constructed and analysed for ysc alpha-mediated and yscY-mediated degradation. Chromatographic analysis of the expression products confirmed the preference of ysc alpha for basic amino acids, although Tyr, Leu and Gln were also hydrolysed. It could further be concluded that ysc alpha might also be responsible for the C-terminal degradation of recombinant atrial natriuretic factor and epidermal growth factor expressed in yeast.
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Affiliation(s)
- J Heim
- Ciba-Geigy Ltd., Biotechnology Department, Basel, Switzerland
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12
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Expression, purification, and characterization of the yeast KEX1 gene product, a polypeptide precursor processing carboxypeptidase. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)54184-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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13
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Affiliation(s)
- G W Gooday
- Department of Molecular and Cell Biology, University of Aberdeen, UK
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14
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Wagner JC, Wolf DH. Purification and characterization of proteinase yscJ, a new yeast peptidase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1992; 203:571-5. [PMID: 1735442 DOI: 10.1111/j.1432-1033.1992.tb16585.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A newly recognized peptidase, designated proteinase yscJ, was purified from the yeast Saccharomyces cerevisiae. The enzyme is of non-vacuolar origin and cleaves the Tyr-Lys bond of the synthetic peptide substrate Cbz-Tyr-Lys-Arg-NH-Ph (Cbz, benzyloxycarbonyl; NH-Ph, 4-nitroanilide) and the Glu-Lys bond of the substrate Boc-Glu-Lys-Lys-NH-Mec (Boc, butoxycarbonyl; Mec, 4-methylcoumarinyl) with high efficiency. Optimum pH for cleavage of Cbz-Tyr-Lys-Arg-NH-Ph is in the range 7.0-7.5. The purified enzyme has a molecular mass of approximately 58 kDa, as judged by gel filtration on a Superose 12 FPLC column. Mercury compounds and EDTA were found to be potent inhibitors of proteinase yscJ activity.
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Affiliation(s)
- J C Wagner
- Institut für Biochemie, Universität Stuttgart, Federal Republic of Germany
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15
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Abstract
Many newly synthesized proteins must be translocated across one or more membranes to reach their destination in the individual organelles or membrane systems. Translocation, mostly requiring an energy source, a signal on the protein itself, loose conformation of the protein and the presence of cytosolic and/or membrane receptor-like proteins, is often accompanied by covalent modifications of transported proteins. In this review I discuss these aspects of protein transport via the classical secretory pathway and/or special translocation mechanisms in the unicellular eukaryotic organism Saccharomyces cerevisiae.
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Affiliation(s)
- J Horák
- Institute of Physiology, Czechoslovak Academy of Sciences, Prague
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16
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Glycosylation and structure of the yeast MF alpha 1 alpha-factor precursor is important for efficient transport through the secretory pathway. J Bacteriol 1991; 173:627-35. [PMID: 1987155 PMCID: PMC207053 DOI: 10.1128/jb.173.2.627-635.1991] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The MF alpha 1 gene encodes a precursor, prepro-alpha-factor, that undergoes several proteolytic processing steps within the classical secretory pathway to produce the mature peptide pheromone, alpha-factor. To investigate the role of structural features of the MF alpha 1 precursor in alpha-factor production, we analyzed the effect of mf alpha 1 mutations that alter precursor structure in a number of ways. These mutations resulted in decreased alpha-factor secretion and intracellular accumulation of pro-alpha-factor. With the exception of the mutant lacking all three N glycosylation sites, the pro-alpha-factor forms that accumulated were core glycosylated but had not yet undergone the addition of outer chain carbohydrate. The delay, therefore, occurred at a step prior to the first proteolytic processing step involved in maturation of the precursor and was probably due to inefficient endoplasmic reticulum-to-Golgi transport. Elimination of all three N-glycosylation sites caused a delay in disappearance of intracellular precursor, and alpha-factor secretion was also slowed. These data indicate that N glycosylation is important but not essential for transport of the precursor through the secretory pathway. The decreased alpha-factor secretion and increased precursor accumulation seen with many different structural changes of pro-alpha-factor indicate that the secretory pathway is extremely sensitive to changes in precursor structure. This sensitivity could cause inefficient secretion of heterologous proteins and hybrids between MF alpha 1 and heterologous proteins in yeast cells.
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17
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Sleep D, Belfield GP, Goodey AR. The Secretion of Human Serum Albumin from the Yeast Saccharomyces cerevisiae Using Five Different Leader Sequences. Nat Biotechnol 1990; 8:42-6. [PMID: 1366511 DOI: 10.1038/nbt0190-42] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We demonstrate the secretion of human serum albumin into the culture supernatant from the yeast Saccharomyces cerevisiae. Studies with five KEX2 processed leader sequences, namely the S. cerevisiae alpha factor, the natural human serum albumin, the Kluyveromyces lactis killer, a natural human serum albumin/alpha factor fusion, and a Kluyveromyces lactis killer/alpha factor fusion leader, are described. We show that the leader sequence used to direct secretion influences the quantity and quality of the secreted product. In designing secretion systems for heterologous proteins, one aims to maximise both the yield and fidelity of the product. Our results indicate that the choice of leader sequence and its relationship to the structural protein under study are crucial to the success of this process.
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Affiliation(s)
- D Sleep
- Delta Biotechnology Limited, Nottingham, Great Britain
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18
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Characterization of the yeast KEX1 gene product: a carboxypeptidase involved in processing secreted precursor proteins. Mol Cell Biol 1989. [PMID: 2668738 DOI: 10.1128/mcb.9.6.2706] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have identified and partially characterized the Saccharomyces cerevisiae KEX1 gene product, Kex1p, to assess its role in processing secreted protein precursors. Anti-Kex1p antibodies identified a 113-kilodalton protein that was absent in cells in which the KEX1 gene has been disrupted and that was more abundant in cells overexpressing the KEX1 gene. Kex1p was found to be a membrane-associated glycoprotein with N-linked carbohydrate. The N-linked oligosaccharide(s) was modified in a progressive manner after synthesis, causing the glycoprotein to slowly increase in mass to 115 kilodaltons. After a Kex2p-mediated cleavage event at specific pairs of basic amino acids, alpha-factor and K1 killer toxin precursors have COOH-terminal dibasic residue extensions and require a carboxypeptidase B-like enzyme to process the precursors to maturity. A carboxypeptidase activity, with apparent specificity for basic amino acids, was detected in KEX1 cells. Disruption of the KEX1 gene abolished this activity, while overexpression of KEX1 increased it. Our results provide biochemical evidence consistent with earlier genetic work, that KEX1 encodes a serine carboxypeptidase involved in the processing of precursors to secreted mature proteins.
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19
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Cooper A, Bussey H. Characterization of the yeast KEX1 gene product: a carboxypeptidase involved in processing secreted precursor proteins. Mol Cell Biol 1989; 9:2706-14. [PMID: 2668738 PMCID: PMC362343 DOI: 10.1128/mcb.9.6.2706-2714.1989] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
We have identified and partially characterized the Saccharomyces cerevisiae KEX1 gene product, Kex1p, to assess its role in processing secreted protein precursors. Anti-Kex1p antibodies identified a 113-kilodalton protein that was absent in cells in which the KEX1 gene has been disrupted and that was more abundant in cells overexpressing the KEX1 gene. Kex1p was found to be a membrane-associated glycoprotein with N-linked carbohydrate. The N-linked oligosaccharide(s) was modified in a progressive manner after synthesis, causing the glycoprotein to slowly increase in mass to 115 kilodaltons. After a Kex2p-mediated cleavage event at specific pairs of basic amino acids, alpha-factor and K1 killer toxin precursors have COOH-terminal dibasic residue extensions and require a carboxypeptidase B-like enzyme to process the precursors to maturity. A carboxypeptidase activity, with apparent specificity for basic amino acids, was detected in KEX1 cells. Disruption of the KEX1 gene abolished this activity, while overexpression of KEX1 increased it. Our results provide biochemical evidence consistent with earlier genetic work, that KEX1 encodes a serine carboxypeptidase involved in the processing of precursors to secreted mature proteins.
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Affiliation(s)
- A Cooper
- Department of Biology, McGill University, Quebec, Canada
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20
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Affiliation(s)
- J Rothblatt
- Department of Biochemistry, University of California, Berkeley 94720
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21
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Affiliation(s)
- H Bussey
- Department of Biology, McGill University, Montreal, Quebec, Canada
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