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Jadhav R, Mach RL, Mach-Aigner AR. Protein secretion and associated stress in industrially employed filamentous fungi. Appl Microbiol Biotechnol 2024; 108:92. [PMID: 38204136 PMCID: PMC10781871 DOI: 10.1007/s00253-023-12985-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 12/21/2023] [Accepted: 12/22/2023] [Indexed: 01/12/2024]
Abstract
Application of filamentous fungi for the production of commercial enzymes such as amylase, cellulase, or xylanase is on the rise due to the increasing demand to degrade several complex carbohydrates as raw material for biotechnological processes. Also, protein production by fungi for food and feed gains importance. In any case, the protein production involves both cellular synthesis and secretion outside of the cell. Unfortunately, the secretion of proteins or enzymes can be hampered due to accumulation of unfolded or misfolded proteins in the endoplasmic reticulum (ER) as a result of too high synthesis of enzymes or (heterologous) protein expression. To cope with this ER stress, the cell generates a response known as unfolded protein response (UPR). Even though this mechanism should re-establish the protein homeostasis equivalent to a cell under non-stress conditions, the enzyme expression might still suffer from repression under secretory stress (RESS). Among eukaryotes, Saccharomyces cerevisiae is the only fungus, which is studied quite extensively to unravel the UPR pathway. Several homologs of the proteins involved in this signal transduction cascade are also found in filamentous fungi. Since RESS seems to be absent in S. cerevisiae and was only reported in Trichoderma reesei in the presence of folding and glycosylation inhibitors such as dithiothreitol and tunicamycin, more in-depth study about this mechanism, specifically in filamentous fungi, is the need of the hour. Hence, this review article gives an overview on both, protein secretion and associated stress responses in fungi. KEY POINTS: • Enzymes produced by filamentous fungi are crucial in industrial processes • UPR mechanism is conserved among many fungi, but mediated by different proteins • RESS is not fully understood or studied in industrially relevant filamentous fungi.
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Affiliation(s)
- Reshma Jadhav
- Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Gumpendorfer Str. 1a, A-1060, Vienna, Austria
- Christian Doppler Laboratory for Optimized Expression of Carbohydrate-Active Enzymes, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Gumpendorfer Str. 1a, A-1060, Vienna, Austria
| | - Robert L Mach
- Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Gumpendorfer Str. 1a, A-1060, Vienna, Austria
| | - Astrid R Mach-Aigner
- Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Gumpendorfer Str. 1a, A-1060, Vienna, Austria.
- Christian Doppler Laboratory for Optimized Expression of Carbohydrate-Active Enzymes, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Gumpendorfer Str. 1a, A-1060, Vienna, Austria.
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Yamamoto R, Miki H, Itani A, Takeshita N. Hyphae of the fungus Aspergillus nidulans demonstrate chemotropism to nutrients and pH. PLoS Biol 2024; 22:e3002726. [PMID: 39078817 PMCID: PMC11288418 DOI: 10.1371/journal.pbio.3002726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2024] [Accepted: 06/28/2024] [Indexed: 08/02/2024] Open
Abstract
The importance of fungi in ecological systems and pathogenicity hinges on their ability to search for nutrients, substrates, and hosts. Despite this, the question of whether fungal hyphae exhibit chemotropism toward them remains largely unresolved and requires close examination at the cellular level. Here, we designed a microfluidic device to assess hyphal chemotropism of Aspergillus nidulans in response to carbon and nitrogen sources, as well as pH. Within this device, hyphae could determine their growth direction in a two-layer flow with distinct compositions that were adjacent but non-mixing. Under conditions with and without a carbon source, hyphae changed growth direction to remain in the presence of a carbon source, but it was still difficult to distinguish between differences in growth and chemotropism. Although nitrogen sources such as ammonia and nitrate are important for growth, the hyphae indicated negative chemotropism to avoid them depending on the specific transporters. This fungus grows equally well at the colony level in the pH range of 4 to 9, but the hyphae exhibited chemotropism to acidic pH. The proton pump PmaA is vital for the chemotropism to acid pH, while the master regulatory for pH adaptation PacC is not involved, suggesting that chemotropism and adaptive growth via gene expression regulation are distinct regulatory mechanisms. Despite various plasma membrane transporters are distributed across membranes except at the hyphal tip, the control of growth direction occurs at the tip. Finally, we explored the mechanisms linking these two phenomena, tip growth and chemotropism.
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Affiliation(s)
- Riho Yamamoto
- Microbiology Research Center for Sustainability (MiCS), Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | - Hinata Miki
- Microbiology Research Center for Sustainability (MiCS), Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | - Ayaka Itani
- Microbiology Research Center for Sustainability (MiCS), Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | - Norio Takeshita
- Microbiology Research Center for Sustainability (MiCS), Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
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Dimou S, Dionysopoulou M, Sagia GM, Diallinas G. Golgi-Bypass Is a Major Unconventional Route for Translocation to the Plasma Membrane of Non-Apical Membrane Cargoes in Aspergillus nidulans. Front Cell Dev Biol 2022; 10:852028. [PMID: 35465316 PMCID: PMC9021693 DOI: 10.3389/fcell.2022.852028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 03/03/2022] [Indexed: 11/13/2022] Open
Abstract
Nutrient transporters have been shown to translocate to the plasma membrane (PM) of the filamentous fungus Aspergillus nidulans via an unconventional trafficking route that bypasses the Golgi. This finding strongly suggests the existence of distinct COPII vesicle subpopulations, one following Golgi-dependent conventional secretion and the other directed towards the PM. Here, we address whether Golgi-bypass concerns cargoes other than nutrient transporters and whether Golgi-bypass is related to cargo structure, size, abundance, physiological function, or polar vs. non-polar distribution in the PM. To address these questions, we followed the dynamic subcellular localization of two selected membrane cargoes differing in several of the aforementioned aspects. These are the proton-pump ATPase PmaA and the PalI pH signaling component. Our results show that neosynthesized PmaA and PalI are translocated to the PM via Golgi-bypass, similar to nutrient transporters. In addition, we showed that the COPII-dependent exit of PmaA from the ER requires the alternative COPII coat subunit LstA, rather than Sec24, whereas PalI requires the ER cargo adaptor Erv14. These findings strengthen the evidence of distinct cargo-specific COPII subpopulations and extend the concept of Golgi-independent biogenesis to essential transmembrane proteins, other than nutrient transporters. Overall, our findings point to the idea that Golgi-bypass might not constitute a fungal-specific peculiarity, but rather a novel major and cargo-specific sorting route in eukaryotic cells that has been largely ignored.
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Affiliation(s)
- Sofia Dimou
- Department of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, Athens, Greece
| | - Mariangela Dionysopoulou
- Department of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, Athens, Greece
| | - Georgia Maria Sagia
- Department of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, Athens, Greece
| | - George Diallinas
- Department of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, Athens, Greece
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion, Greece
- *Correspondence: George Diallinas,
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The Exocyst Regulates Hydrolytic Enzyme Secretion at Hyphal Tips and Septa in the Banana Fusarium Wilt Fungus Fusarium odoratissimum. Appl Environ Microbiol 2021; 87:e0308820. [PMID: 34132587 DOI: 10.1128/aem.03088-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hyphal polarized growth in filamentous fungi requires tip-directed secretion, while additional evidence suggests that fungal exocytosis for the hydrolytic enzyme secretion can occur at other sites in hyphae, including the septum. In this study, we analyzed the role of the exocyst complex involved in the secretion in the banana wilt fungal pathogen Fusarium odoratissimum. All eight exocyst components in F. odoratissimum not only localized to the tips ahead of the Spitzenkörper in growing hyphae but also localized to the outer edges of septa in mature hyphae. To further analyze the exocyst in F. odoratissimum, we attempted single gene deletion for all the genes encoding the eight exocyst components and only succeeded in constructing the gene deletion mutants for exo70 and sec5; we suspect that the other 6 exocyst components are encoded by essential genes. Deletion of exo70 or sec5 led to defects in vegetative growth, conidiation, and pathogenicity in F. odoratissimum. Notably, the deletion of exo70 resulted in decreased activities for endoglucosidase, filter paper enzymes, and amylase, while the loss of sec5 only led to a slight reduction in amylase activity. Septum-localized α-amylase (AmyB) was identified as the marker for septum-directed secretion, and we found that Exo70 is essential for the localization of AmyB to septa. Meanwhile the loss of Sec5 did not affect AmyB localization to septa but led to a higher accumulation of AmyB in cytoplasm. This suggested that while Exo70 and Sec5 both take part in the septum-directed secretion, the two play different roles in this process. IMPORTANCE The exocyst complex is a multisubunit tethering complex (MTC) for secretory vesicles at the plasma membrane and contains eight subunits, Sec3, Sec5, Sec6, Sec8, Sec10, Sec15, Exo70, and Exo84. While the exocyst complex is well defined in eukaryotes from yeast (Saccharomyces cerevisiae) to humans, the exocyst components in filamentous fungi show different localization patterns in the apical tips of hyphae, which suggests that filamentous fungi have evolved divergent strategies to regulate endomembrane trafficking. In this study, we demonstrated that the exocyst components in Fusarium odoratissimum are localized not only to the tips of growing hyphae but also to the outer edge of the septa in mature hyphae, suggesting that the exocyst complex plays a role in the regulation of septum-directed protein secretion in F. odoratissimum. We further found that Exo70 and Sec5 are required for the septum-directed secretion of α-amylase in F. odoratissimum but with different influences.
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Emri T, Gila B, Antal K, Fekete F, Moon H, Yu JH, Pócsi I. AtfA-Independent Adaptation to the Toxic Heavy Metal Cadmium in Aspergillus nidulans. Microorganisms 2021; 9:microorganisms9071433. [PMID: 34361869 PMCID: PMC8307709 DOI: 10.3390/microorganisms9071433] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 06/28/2021] [Accepted: 06/30/2021] [Indexed: 12/13/2022] Open
Abstract
Cadmium is an exceptionally toxic industrial and environmental pollutant classified as a human carcinogen. In order to provide insight into how we can keep our environment safe from cadmium contamination and prevent the accumulation of it in the food chain, we aim to elucidate how Aspergillus nidulans, one of the most abundant fungi in soil, survives and handles cadmium stress. As AtfA is the main transcription factor governing stress responses in A. nidulans, we examined genome-wide expression responses of wild-type and the atfA null mutant exposed to CdCl2. Both strains showed up-regulation of the crpA Cu2+/Cd2+ pump gene and AN7729 predicted to encode a putative bis(glutathionato)-cadmium transporter, and transcriptional changes associated with elevated intracellular Cys availability leading to the efficient adaptation to Cd2+. Although the deletion of atfA did not alter the cadmium tolerance of the fungus, the cadmium stress response of the mutant differed from that of a reference strain. Promoter and transcriptional analyses of the “Phospho-relay response regulator” genes suggest that the AtfA-dependent regulation of these genes can be relevant in this phenomenon. We concluded that the regulatory network of A. nidulans has a high flexibility allowing the fungus to adapt efficiently to stress both in the presence and absence of this important transcription factor.
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Affiliation(s)
- Tamás Emri
- Department of Molecular Biotechnology and Microbiology, Faculty of Sciences and Technology, University of Debrecen, 4032 Debrecen, Hungary; (B.G.); (F.F.); (I.P.)
- Correspondence:
| | - Barnabás Gila
- Department of Molecular Biotechnology and Microbiology, Faculty of Sciences and Technology, University of Debrecen, 4032 Debrecen, Hungary; (B.G.); (F.F.); (I.P.)
- Doctoral School of Nutrition and Food Sciences, University of Debrecen, 4032 Debrecen, Hungary
| | - Károly Antal
- Department of Zoology, Eszterházy Károly University, 3300 Eger, Hungary;
| | - Fanni Fekete
- Department of Molecular Biotechnology and Microbiology, Faculty of Sciences and Technology, University of Debrecen, 4032 Debrecen, Hungary; (B.G.); (F.F.); (I.P.)
| | - Heungyun Moon
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA; (H.M.); (J.-H.Y.)
| | - Jae-Hyuk Yu
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA; (H.M.); (J.-H.Y.)
- Department of Systems Biotechnology, Konkuk University, Seoul 05029, Korea
| | - István Pócsi
- Department of Molecular Biotechnology and Microbiology, Faculty of Sciences and Technology, University of Debrecen, 4032 Debrecen, Hungary; (B.G.); (F.F.); (I.P.)
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Santos FC, Marquês JT, Bento‐Oliveira A, Almeida RF. Sphingolipid‐enriched domains in fungi. FEBS Lett 2020; 594:3698-3718. [DOI: 10.1002/1873-3468.13986] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 09/21/2020] [Accepted: 10/13/2020] [Indexed: 12/11/2022]
Affiliation(s)
- Filipa C. Santos
- Centro de Química Estrutural Faculdade de Ciências, Universidade de Lisboa Campo Grande Portugal
| | - Joaquim T. Marquês
- Centro de Química Estrutural Faculdade de Ciências, Universidade de Lisboa Campo Grande Portugal
| | - Andreia Bento‐Oliveira
- Centro de Química Estrutural Faculdade de Ciências, Universidade de Lisboa Campo Grande Portugal
| | - Rodrigo F.M. Almeida
- Centro de Química Estrutural Faculdade de Ciências, Universidade de Lisboa Campo Grande Portugal
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Zhgun A, Dumina M, Valiakhmetov A, Eldarov M. The critical role of plasma membrane H+-ATPase activity in cephalosporin C biosynthesis of Acremonium chrysogenum. PLoS One 2020; 15:e0238452. [PMID: 32866191 PMCID: PMC7458343 DOI: 10.1371/journal.pone.0238452] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 08/16/2020] [Indexed: 11/19/2022] Open
Abstract
The filamentous fungus Acremonium chrysogenum is the main industrial producer of cephalosporin C (CPC), one of the major precursors for manufacturing of cephalosporin antibiotics. The plasma membrane H+-ATPase (PMA) plays a key role in numerous fungal physiological processes. Previously we observed a decrease of PMA activity in A. chrysogenum overproducing strain RNCM 408D (HY) as compared to the level the wild-type strain A. chrysogenum ATCC 11550. Here we report the relationship between PMA activity and CPC biosynthesis in A. chrysogenum strains. The elevation of PMA activity in HY strain through overexpression of PMA1 from Saccharomyces cerevisiae, under the control of the constitutive gpdA promoter from Aspergillus nidulans, results in a 1.2 to 10-fold decrease in CPC production, shift in beta-lactam intermediates content, and is accompanied by the decrease in cef genes expression in the fermentation process; the characteristic colony morphology on agar media is also changed. The level of PMA activity in A. chrysogenum HY OE::PMA1 strains has been increased by 50–100%, up to the level observed in WT strain, and was interrelated with ATP consumption; the more PMA activity is elevated, the more ATP level is depleted. The reduced PMA activity in A. chrysogenum HY strain may be one of the selected events during classical strain improvement, aimed at elevating the ATP content available for CPC production.
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Affiliation(s)
- Alexander Zhgun
- Research Center of Biotechnology RAS, Moscow, Russia
- * E-mail:
| | - Mariya Dumina
- Research Center of Biotechnology RAS, Moscow, Russia
| | - Ayrat Valiakhmetov
- Skryabin Institute of Biophysics and Physiology of Microorganisms, RAS, Pushchino, Russia
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Bento-Oliveira A, Santos FC, Marquês JT, Paulo PMR, Korte T, Herrmann A, Marinho HS, de Almeida RFM. Yeast Sphingolipid-Enriched Domains and Membrane Compartments in the Absence of Mannosyldiinositolphosphorylceramide. Biomolecules 2020; 10:biom10060871. [PMID: 32517183 PMCID: PMC7356636 DOI: 10.3390/biom10060871] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 05/25/2020] [Accepted: 06/02/2020] [Indexed: 12/14/2022] Open
Abstract
The relevance of mannosyldiinositolphosphorylceramide [M(IP)2C] synthesis, the terminal complex sphingolipid class in the yeast Saccharomyces cerevisiae, for the lateral organization of the plasma membrane, and in particular for sphingolipid-enriched gel domains, was investigated by fluorescence spectroscopy and microscopy. We also addressed how changing the complex sphingolipid profile in the plasma membrane could influence the membrane compartments (MC) containing either the arginine/ H+ symporter Can1p (MCC) or the proton ATPase Pma1p (MCP). To achieve these goals, wild-type (wt) and ipt1Δ cells, which are unable to synthesize M(IP)2C accumulating mannosylinositolphosphorylceramide (MIPC), were compared. Living cells, isolated plasma membrane and giant unilamellar vesicles reconstituted from plasma membrane lipids were labelled with various fluorescent membrane probes that report the presence and organization of distinct lipid domains, global order, and dielectric properties. Can1p and Pma1p were tagged with GFP and mRFP, respectively, in both yeast strains, to evaluate their lateral organization using confocal fluorescence intensity and fluorescence lifetime imaging. The results show that IPT1 deletion strongly affects the rigidity of gel domains but not their relative abundance, whereas no significant alterations could be perceived in ergosterol-enriched domains. Moreover, in these cells lacking M(IP)2C, a clear alteration in Pma1p membrane distribution, but no significant changes in Can1p distribution, were observed. Thus, this work reinforces the notion that sphingolipid-enriched domains distinct from ergosterol-enriched regions are present in the S. cerevisiae plasma membrane and suggests that M(IP)2C is important for a proper hydrophobic chain packing of sphingolipids in the gel domains of wt cells. Furthermore, our results strongly support the involvement of sphingolipid domains in the formation and stability of the MCP, possibly being enriched in this compartment.
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Affiliation(s)
- Andreia Bento-Oliveira
- Centro de Química Estrutural, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisbon, Portugal; (A.B.-O.); (F.C.S.); (J.T.M.); (H.S.M.)
| | - Filipa C. Santos
- Centro de Química Estrutural, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisbon, Portugal; (A.B.-O.); (F.C.S.); (J.T.M.); (H.S.M.)
| | - Joaquim Trigo Marquês
- Centro de Química Estrutural, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisbon, Portugal; (A.B.-O.); (F.C.S.); (J.T.M.); (H.S.M.)
| | - Pedro M. R. Paulo
- Centro de Química Estrutural, Instituto Superior Técnico, 1049-001 Lisbon, Portugal;
| | - Thomas Korte
- Department of Biology, Molecular Biophysics, IRI Life Sciences, Humboldt-Universität zu Berlin, 10115 Berlin, Germany; (T.K.); (A.H.)
| | - Andreas Herrmann
- Department of Biology, Molecular Biophysics, IRI Life Sciences, Humboldt-Universität zu Berlin, 10115 Berlin, Germany; (T.K.); (A.H.)
| | - H. Susana Marinho
- Centro de Química Estrutural, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisbon, Portugal; (A.B.-O.); (F.C.S.); (J.T.M.); (H.S.M.)
| | - Rodrigo F. M. de Almeida
- Centro de Química Estrutural, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisbon, Portugal; (A.B.-O.); (F.C.S.); (J.T.M.); (H.S.M.)
- Correspondence: ; Tel.: +351-217-500-925
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Snyder AB, Biango-Daniels MN, Hodge KT, Worobo RW. Nature Abhors a Vacuum: Highly Diverse Mechanisms Enable Spoilage Fungi to Disperse, Survive, and Propagate in Commercially Processed and Preserved Foods. Compr Rev Food Sci Food Saf 2018; 18:286-304. [DOI: 10.1111/1541-4337.12403] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 09/30/2018] [Accepted: 10/02/2018] [Indexed: 01/01/2023]
Affiliation(s)
- Abigail B. Snyder
- the Dept. of Extension; The Ohio State Univ.; 1680 Madison Ave. Wooster OH 44691 USA
| | - Megan N. Biango-Daniels
- the Plant Pathology and Plant-Microbe Biology, School of Integrated Plant Science; Cornell Univ.; Ithaca NY 14850 USA
| | - Kathie T. Hodge
- the Plant Pathology and Plant-Microbe Biology, School of Integrated Plant Science; Cornell Univ.; Ithaca NY 14850 USA
| | - Randy W. Worobo
- the Dept. of Food Science; Cornell Univ.; 411 Tower Rd. Ithaca NY 14850 USA
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10
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Lipchinsky A. Electromechanics of polarized cell growth. Biosystems 2018; 173:114-132. [PMID: 30300677 DOI: 10.1016/j.biosystems.2018.10.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 09/30/2018] [Accepted: 10/04/2018] [Indexed: 10/28/2022]
Abstract
One of the most challenging questions in cell and developmental biology is how molecular signals are translated into mechanical forces that ultimately drive cell growth and motility. Despite an impressive body of literature demonstrating the importance of cytoskeletal and motor proteins as well as osmotic stresses for cell developmental mechanics, a host of dissenting evidence strongly suggests that these factors per se cannot explain growth mechanics even at the level of a single tip-growing cell. The present study addresses this issue by exploring fundamental interrelations between electrical and mechanical fields operating in cells. In the first instance, we employ a simplified but instructive model of a quiescent cell to demonstrate that even in a quasi-equilibrium state, ion transport processes are conditioned principally by mechanical tenets. Then we inquire into the electromechanical conjugacy in growing pollen tubes as biologically relevant and physically tractable developmental systems owing to their extensively characterized growth-associated ionic fluxes and strikingly polarized growth and morphology. A comprehensive analysis of the multifold stress pattern in the growing apices of pollen tubes suggests that tip-focused ionic fluxes passing through the polyelectrolyte-rich apical cytoplasm give rise to electrokinetic flows that actualize otherwise isotropic intracellular turgor into anisotropic stress field. The stress anisotropy can be then imparted from the apical cytoplasm to the abutting frontal cell wall to induce its local extension and directional cell growth. Converging lines of evidence explored in the concluding sections attest that tip-focused ionic fluxes and associated interfacial transport phenomena are not specific for pollen tubes but are also employed by a vast variety of algal, plant, fungal and animal cells, rendering their cytoplasmic stress fields essentially anisotropic and ultimately instrumental in cell shaping, growth and motility.
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Affiliation(s)
- Andrei Lipchinsky
- Department of Plant Physiology and Biochemistry, St. Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg, 199034, Russia.
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11
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Fiedler MRM, Barthel L, Kubisch C, Nai C, Meyer V. Construction of an improved Aspergillus niger platform for enhanced glucoamylase secretion. Microb Cell Fact 2018; 17:95. [PMID: 29908567 PMCID: PMC6004097 DOI: 10.1186/s12934-018-0941-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 06/08/2018] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND The lifestyle of filamentous fungi depends on the secretion of hydrolytic enzymes into the surrounding medium, which degrade polymeric substances into monomers that are then taken up to sustain metabolism. This feature has been exploited in biotechnology to establish platform strains with high secretory capacity including Aspergillus niger. The accepted paradigm is that proteins become mainly secreted at the tips of fungal hyphae. However, it is still a matter of debate if the amount of growing hyphal tips in filamentous fungi correlates with an increase in secretion, with previous studies showing either a positive or no correlation. RESULTS Here, we followed a systematic approach to study protein secretion in A. niger. First, we put the glaA gene encoding for glucoamylase (GlaA), the most abundant secreted protein of A. niger, under control of the tunable Tet-on system. Regulation of glaA gene expression by omitting or adding the inducer doxycycline to cultivation media allowed us to study the effect of glaA under- or overexpression in the same isolate. By inducing glaA expression in a fluorescently tagged v-SNARE reporter strain expressing GFP-SncA, we could demonstrate that the amount of post-Golgi carriers indeed depends on and correlates with glaA gene expression. By deleting the racA gene, encoding the Rho-GTPase RacA in this isolate, we generated a strain which is identical to the parental strain with respect to biomass formation but produces about 20% more hyphal tips. This hyperbranching phenotype caused a more compact macromorphology in shake flask cultivations. When ensuring continuous high-level expression of glaA by repeated addition of doxycycline, this hyperbranching strain secreted up to four times more GlaA into the culture medium compared to its parental strain. CONCLUSION The data obtained in this study strongly indicate that A. niger responds to forced transcription of secretory enzymes with increased formation of post-Golgi carriers to efficiently accommodate the incoming cargo load. This physiological adaptation can be rationally exploited to generate hypersecretion platforms based on a hyperbranching phenotype. We propose that a racA deletion background serves as an excellent chassis for such hypersecretion strains.
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Affiliation(s)
- Markus R. M. Fiedler
- Department Applied and Molecular Microbiology, Institute of Biotechnology, Technische Universität Berlin, Gustav-Meyer-Allee 25, 13355 Berlin, Germany
| | - Lars Barthel
- Department Applied and Molecular Microbiology, Institute of Biotechnology, Technische Universität Berlin, Gustav-Meyer-Allee 25, 13355 Berlin, Germany
| | - Christin Kubisch
- Department Applied and Molecular Microbiology, Institute of Biotechnology, Technische Universität Berlin, Gustav-Meyer-Allee 25, 13355 Berlin, Germany
| | - Corrado Nai
- Department Applied and Molecular Microbiology, Institute of Biotechnology, Technische Universität Berlin, Gustav-Meyer-Allee 25, 13355 Berlin, Germany
| | - Vera Meyer
- Department Applied and Molecular Microbiology, Institute of Biotechnology, Technische Universität Berlin, Gustav-Meyer-Allee 25, 13355 Berlin, Germany
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Starr TL, Gonçalves AP, Meshgin N, Glass NL. The major cellulases CBH-1 and CBH-2 of Neurospora crassa rely on distinct ER cargo adaptors for efficient ER-exit. Mol Microbiol 2017; 107:229-248. [PMID: 29131484 DOI: 10.1111/mmi.13879] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/10/2017] [Indexed: 12/17/2022]
Abstract
Filamentous fungi are native secretors of lignocellulolytic enzymes and are used as protein-producing factories in the industrial biotechnology sector. Despite the importance of these organisms in industry, relatively little is known about the filamentous fungal secretory pathway or how it might be manipulated for improved protein production. Here, we use Neurospora crassa as a model filamentous fungus to interrogate the requirements for trafficking of cellulase enzymes from the endoplasmic reticulum to the Golgi. We characterized the localization and interaction properties of the p24 and ERV-29 cargo adaptors, as well as their role in cellulase enzyme trafficking. We find that the two most abundantly secreted cellulases, CBH-1 and CBH-2, depend on distinct ER cargo adaptors for efficient exit from the ER. CBH-1 depends on the p24 proteins, whereas CBH-2 depends on the N. crassa homolog of yeast Erv29p. This study provides a first step in characterizing distinct trafficking pathways of lignocellulolytic enzymes in filamentous fungi.
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Affiliation(s)
- Trevor L Starr
- The Energy Biosciences Institute, The University of California, Berkeley, CA 94720, USA
| | - A Pedro Gonçalves
- The Energy Biosciences Institute, The University of California, Berkeley, CA 94720, USA.,Plant and Microbial Biology Department, The University of California, Berkeley, CA 94720, USA
| | - Neeka Meshgin
- The Energy Biosciences Institute, The University of California, Berkeley, CA 94720, USA
| | - N Louise Glass
- The Energy Biosciences Institute, The University of California, Berkeley, CA 94720, USA.,Plant and Microbial Biology Department, The University of California, Berkeley, CA 94720, USA.,Environmental Genomics and Systems Biology Division, The Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
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13
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Zhu J, Zhu XG, Ying SH, Feng MG. Effect of vacuolar ATPase subunit H (VmaH) on cellular pH, asexual cycle, stress tolerance and virulence in Beauveria bassiana. Fungal Genet Biol 2016; 98:52-60. [PMID: 28011319 DOI: 10.1016/j.fgb.2016.12.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Revised: 12/11/2016] [Accepted: 12/19/2016] [Indexed: 12/23/2022]
Abstract
Vacuolar ATPase (V-ATPase) is a conserved multi-subunit protein complex that mediates intracellular acidification in fungi. Here we show functional diversity of V-ATPase subunit H (BbVmaH) in Beauveria bassiana, a filamentous fungal insect pathogen. Deletion of BbvmaH resulted in elevated vacuolar pH, increased Ca2+ level in cytosol but not in vacuoles, accelerated culture acidification and reduced accumulation of extracellular ammonia. Aerial conidiation and submerged blastospore production were largely delayed and reduced in the deletion mutant, respectively, accompanied with a significant delay in conidial germination, alterations of conidia and blastospores in morphology, size and/or density, and severe growth defects in minimal media with different carbon and nitrogen sources. Despite null responses to osmotic, oxidative and cell wall perturbing stresses, the deletion mutant showed increased sensitivity to Ca2+, Zn2+ and Cu2+ during growth while its conidia were less tolerant to a wet-heat stress at 45°C and UV-B irradiation. Intracellular glycerol and mannitol contents also decreased significantly. Its virulence to Galleria mellonella larvae was significantly attenuated when conidia were topically applied for normal cuticle infection or injected into haemocoel for cuticle-bypassing infection. All phenotypic changes were restored by targeted gene complementation. Our results indicate that BbVmaH plays an important role in sustaining not only vacuolar acidification but also cytosolic calcium accumulation, ambient pH homeostasis, in vitro asexual cycle and virulence in B. bassiana.
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Affiliation(s)
- Jing Zhu
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Xiao-Guan Zhu
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Sheng-Hua Ying
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Ming-Guang Feng
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China.
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14
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Reilly MC, Magnuson JK, Baker SE. Approaches to understanding protein hypersecretion in fungi. FUNGAL BIOL REV 2016. [DOI: 10.1016/j.fbr.2016.06.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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15
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Martínez-Núñez L, Riquelme M. Role of BGT-1 and BGT-2, two predicted GPI-anchored glycoside hydrolases/glycosyltransferases, in cell wall remodeling in Neurospora crassa. Fungal Genet Biol 2015; 85:58-70. [PMID: 26541633 DOI: 10.1016/j.fgb.2015.11.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 10/25/2015] [Accepted: 11/01/2015] [Indexed: 02/07/2023]
Abstract
Neurospora crassa BGT-1 (NCU06381) and BGT-2 (NCU09175) are two putative glycoside hydrolases (GHs) with additional predicted glycosyltransferase activity and binding sites for a glycosyl phosphatidyl inositol (GPI) anchor that would facilitate their attachment to the plasma membrane (PM). To discern their role in key morphogenetic events during vegetative development of N. crassa, BGT-1 and BGT-2 were labeled with the green fluorescent protein (GFP). The gfp was inserted immediately after the signal peptide sequence, within the bgt-1 encoding sequence, or directly before the GPI-binding site in the case of bgt-2. Both BGT-1-GFP and BGT-2-GFP were observed at the PM of the hyphal apical dome, excluding the foremost apical region and the Spitzenkörper (Spk), where chitin and β-1,3-glucan synthases have been previously found. These and previous studies suggest a division of labor of the cell wall synthesizing machinery at the hyphal dome: at the very tip, glucans are synthesized by enzymes that accumulate at the Spk, before getting incorporated into the PM, whereas at the subtending zone below the apex, glucans are presumably hydrolyzed, producing amenable ends for further branching and crosslinking with other cell wall polymers. Additionally, BGT-1-GFP and BGT-2-GFP were observed at the leading edge of new developing septa, at unreleased interconidial junctions, at conidial poles, at germling and hyphal fusion sites, and at sites of branch emergence, all of them processes that seemingly involve cell wall remodeling. Even though single and double mutant strains for the corresponding genes did not show a drastic reduction of growth rate, bgt-2Δ and bgt-1Δ::bgt-2Δ strains exhibited an increased resistance to the cell wall stressors calcofluor white (CW) and congo red (CR) than the reference strain, which suggests they present significant architectural changes in their cell wall. Furthermore, the conidiation defects observed in the mutants indicate a significant role of BGT-1 and BGT-2 on the re-arrangement of glucans needed at the conidiophore cell wall to allow conidial separation.
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Affiliation(s)
- Leonora Martínez-Núñez
- Department of Microbiology, Centro de Investigación Científica y de Educación Superior de Ensenada-CICESE, Ensenada, Baja California 22860, Mexico
| | - Meritxell Riquelme
- Department of Microbiology, Centro de Investigación Científica y de Educación Superior de Ensenada-CICESE, Ensenada, Baja California 22860, Mexico.
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Characterization of a Novel Prevacuolar Compartment in Neurospora crassa. EUKARYOTIC CELL 2015; 14:1253-63. [PMID: 26453652 DOI: 10.1128/ec.00128-15] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 10/03/2015] [Indexed: 12/22/2022]
Abstract
Using confocal microscopy, we observed ring-like organelles, similar in size to nuclei, in the hyphal tip of the filamentous fungus Neurospora crassa. These organelles contained a subset of vacuolar proteins. We hypothesize that they are novel prevacuolar compartments (PVCs). We examined the locations of several vacuolar enzymes and of fluorescent compounds that target the vacuole. Vacuolar membrane proteins, such as the vacuolar ATPase (VMA-1) and the polyphosphate polymerase (VTC-4), were observed in the PVCs. A pigment produced by adenine auxotrophs, used to visualize vacuoles, also accumulated in PVCs. Soluble enzymes of the vacuolar lumen, alkaline phosphatase and carboxypeptidase Y, were not observed in PVCs. The fluorescent molecule Oregon Green 488 carboxylic acid diacetate, succinimidyl ester (carboxy-DFFDA) accumulated in vacuoles and in a subset of PVCs, suggesting maturation of PVCs from the tip to distal regions. Three of the nine Rab GTPases in N. crassa, RAB-2, RAB-4, and RAB-7, localized to the PVCs. RAB-2 and RAB-4, which have similar amino acid sequences, are present in filamentous fungi but not in yeasts, and no function has previously been reported for these Rab GTPases in fungi. PVCs are highly pleomorphic, producing tubular projections that subsequently become detached. Dynein and dynactin formed globular clusters enclosed inside the lumen of PVCs. The size, structure, dynamic behavior, and protein composition of the PVCs appear to be significantly different from those of the well-studied prevacuolar compartment of yeasts.
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Zhao J, Gladieux P, Hutchison E, Bueche J, Hall C, Perraudeau F, Glass NL. Identification of Allorecognition Loci in Neurospora crassa by Genomics and Evolutionary Approaches. Mol Biol Evol 2015; 32:2417-32. [PMID: 26025978 PMCID: PMC4540973 DOI: 10.1093/molbev/msv125] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Understanding the genetic and molecular bases of the ability to distinguish self from nonself (allorecognition) and mechanisms underlying evolution of allorecognition systems is an important endeavor for understanding cases where it becomes dysfunctional, such as in autoimmune disorders. In filamentous fungi, allorecognition can result in vegetative or heterokaryon incompatibility, which is a type of programmed cell death that occurs following fusion of genetically different cells. Allorecognition is genetically controlled by het loci, with coexpression of any combination of incompatible alleles triggering vegetative incompatibility. Herein, we identified, characterized, and inferred the evolutionary history of candidate het loci in the filamentous fungus Neurospora crassa. As characterized het loci encode proteins carrying an HET domain, we annotated HET domain genes in 25 isolates from a natural population along with the N. crassa reference genome using resequencing data. Because allorecognition systems can be affected by frequency-dependent selection favoring rare alleles (i.e., balancing selection), we mined resequencing data for HET domain loci whose alleles displayed elevated levels of variability, excess of intermediate frequency alleles, and deep gene genealogies. From these analyses, 34 HET domain loci were identified as likely to be under balancing selection. Using transformation, incompatibility assays and genetic analyses, we determined that one of these candidates functioned as a het locus (het-e). The het-e locus has three divergent allelic groups that showed signatures of positive selection, intra- and intergroup recombination, and trans-species polymorphism. Our findings represent a compelling case of balancing selection functioning on multiple alleles across multiple loci potentially involved in allorecognition.
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Affiliation(s)
- Jiuhai Zhao
- Plant and Microbial Biology Department, University of California, Berkeley
| | - Pierre Gladieux
- Plant and Microbial Biology Department, University of California, Berkeley INRA, UMR BGPI, TA A54/K, Montpellier, France; CIRAD, Montpellier, France
| | - Elizabeth Hutchison
- Plant and Microbial Biology Department, University of California, Berkeley Biology Department, 1 College Circle SUNY Geneseo, Geneseo, NY
| | - Joanna Bueche
- Plant and Microbial Biology Department, University of California, Berkeley
| | - Charles Hall
- Plant and Microbial Biology Department, University of California, Berkeley
| | - Fanny Perraudeau
- Plant and Microbial Biology Department, University of California, Berkeley Ecole Polytechnique, Palaiseau, France
| | - N Louise Glass
- Plant and Microbial Biology Department, University of California, Berkeley
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Fajardo-Somera RA, Jöhnk B, Bayram Ö, Valerius O, Braus GH, Riquelme M. Dissecting the function of the different chitin synthases in vegetative growth and sexual development in Neurospora crassa. Fungal Genet Biol 2015; 75:30-45. [DOI: 10.1016/j.fgb.2015.01.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 12/17/2014] [Accepted: 01/07/2015] [Indexed: 01/22/2023]
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Meyer V, Fiedler M, Nitsche B, King R. The Cell Factory Aspergillus Enters the Big Data Era: Opportunities and Challenges for Optimising Product Formation. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2015; 149:91-132. [PMID: 25616499 DOI: 10.1007/10_2014_297] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Living with limits. Getting more from less. Producing commodities and high-value products from renewable resources including waste. What is the driving force and quintessence of bioeconomy outlines the lifestyle and product portfolio of Aspergillus, a saprophytic genus, to which some of the top-performing microbial cell factories belong: Aspergillus niger, Aspergillus oryzae and Aspergillus terreus. What makes them so interesting for exploitation in biotechnology and how can they help us to address key challenges of the twenty-first century? How can these strains become trimmed for better growth on second-generation feedstocks and how can we enlarge their product portfolio by genetic and metabolic engineering to get more from less? On the other hand, what makes it so challenging to deduce biological meaning from the wealth of Aspergillus -omics data? And which hurdles hinder us to model and engineer industrial strains for higher productivity and better rheological performance under industrial cultivation conditions? In this review, we will address these issues by highlighting most recent findings from the Aspergillus research with a focus on fungal growth, physiology, morphology and product formation. Indeed, the last years brought us many surprising insights into model and industrial strains. They clearly told us that similar is not the same: there are different ways to make a hypha, there are more protein secretion routes than anticipated and there are different molecular and physical mechanisms which control polar growth and the development of hyphal networks. We will discuss new conceptual frameworks derived from these insights and the future scientific advances necessary to create value from Aspergillus Big Data.
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Affiliation(s)
- Vera Meyer
- Department Applied and Molecular Microbiology, Institute of Biotechnology, Berlin University of Technology, Gustav-Meyer-Allee 25, 13355, Berlin, Germany,
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Affiliation(s)
- Fred Chang
- Department of Microbiology and Immunology, Columbia University College of Physicians and Surgeons, New York, New York 10032;
| | - Nicolas Minc
- Institut Jacques Monod, UMR7592 CNRS, 75205 Paris cedex 13, France;
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Shoji JY, Kikuma T, Kitamoto K. Vesicle trafficking, organelle functions, and unconventional secretion in fungal physiology and pathogenicity. Curr Opin Microbiol 2014; 20:1-9. [PMID: 24835421 DOI: 10.1016/j.mib.2014.03.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Accepted: 03/11/2014] [Indexed: 12/21/2022]
Abstract
Specific localization of appropriate sets of proteins and lipids is central to functions and integrity of organelles, which in turn underlie cellular activities of eukaryotes. Vesicle trafficking is a conserved mechanism of intracellular transport, which ensures such a specific localization to a subset of organelles. In this review article, we summarize recent advances in our understanding of how vesicle trafficking and related organelles support physiology and pathogenicity of filamentous fungi. Examples include a link between Golgi organization and polarity maintenance during hyphal tip growth, a new role of early endosomes in transport of translational machinery, involvement of endosomal/vacuolar compartments in secondary metabolite synthesis, and functions of vacuoles and autophagy in fungal development, nutrient recycling and allocation. Accumulating evidence showing the importance of unconventional secretion in fungal pathogenicity is also summarized.
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Affiliation(s)
- Jun-ya Shoji
- Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Takashi Kikuma
- Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Katsuhiko Kitamoto
- Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
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Palma-Guerrero J, Leeder AC, Welch J, Glass NL. Identification and characterization of LFD1, a novel protein involved in membrane merger during cell fusion in Neurospora crassa. Mol Microbiol 2014; 92:164-82. [PMID: 24673848 DOI: 10.1111/mmi.12545] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/04/2014] [Indexed: 11/30/2022]
Abstract
Despite its essential role in development, molecular mechanisms of membrane merger during cell-cell fusion in most eukaryotic organisms remain elusive. In the filamentous fungus Neurospora crassa, cell fusion occurs during asexual spore germination, where genetically identical germlings show chemotropic interactions and cell-cell fusion. Fusion of germlings and hyphae is required for the formation of the interconnected mycelial network characteristic of filamentous fungi. Previously, a multipass membrane protein, PRM1, was characterized and acts at the step of bilayer fusion in N. crassa. Here we describe the identification and characterization of lfd-1, encoding a single pass transmembrane protein, which is also involved in membrane merger. lfd-1 was identified by a targeted analysis of a transcriptional profile of a transcription factor mutant (Δpp-1) defective in germling fusion. The Δlfd-1 mutant shows a similar, but less severe, membrane merger defect as a ΔPrm1 mutant. By genetic analyses, we show that LFD1 and PRM1 act independently, but share a redundant function. The cell fusion frequency of both Δlfd-1 and ΔPrm1 mutants was sensitive to extracellular calcium concentration and was associated with an increase in cell lysis, which was suppressed by a calcium-dependent mechanism involving a homologue to synaptotagmin.
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Kubicek CP, Starr TL, Glass NL. Plant cell wall-degrading enzymes and their secretion in plant-pathogenic fungi. ANNUAL REVIEW OF PHYTOPATHOLOGY 2014; 52:427-51. [PMID: 25001456 DOI: 10.1146/annurev-phyto-102313-045831] [Citation(s) in RCA: 446] [Impact Index Per Article: 44.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Approximately a tenth of all described fungal species can cause diseases in plants. A common feature of this process is the necessity to pass through the plant cell wall, an important barrier against pathogen attack. To this end, fungi possess a diverse array of secreted enzymes to depolymerize the main structural polysaccharide components of the plant cell wall, i.e., cellulose, hemicellulose, and pectin. Recent advances in genomic and systems-level studies have begun to unravel this diversity and have pinpointed cell wall-degrading enzyme (CWDE) families that are specifically present or enhanced in plant-pathogenic fungi. In this review, we discuss differences between the CWDE arsenal of plant-pathogenic and non-plant-pathogenic fungi, highlight the importance of individual enzyme families for pathogenesis, illustrate the secretory pathway that transports CWDEs out of the fungal cell, and report the transcriptional regulation of expression of CWDE genes in both saprophytic and phytopathogenic fungi.
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