1
|
Lu Y, Lei L, Deng Y, Zhang H, Xia M, Wei X, Yang Y, Hu T. RNase III coding genes modulate the cross-kingdom biofilm of Streptococcus mutans and Candida albicans. Front Microbiol 2022; 13:957879. [PMID: 36246231 PMCID: PMC9563999 DOI: 10.3389/fmicb.2022.957879] [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: 05/31/2022] [Accepted: 08/18/2022] [Indexed: 11/28/2022] Open
Abstract
Streptococcus mutans constantly coexists with Candida albicans in plaque biofilms of early childhood caries (ECC). The progression of ECC can be influenced by the interactions between S. mutans and C. albicans through exopolysaccharides (EPS). Our previous studies have shown that rnc, the gene encoding ribonuclease III (RNase III), is implicated in the cariogenicity of S. mutans by regulating EPS metabolism. The DCR1 gene in C. albicans encodes the sole functional RNase III and is capable of producing non-coding RNAs. However, whether rnc or DCR1 can regulate the structure or cariogenic virulence of the cross-kingdom biofilm of S. mutans and C. albicans is not yet well understood. By using gene disruption or overexpression assays, this study aims to investigate the roles of rnc and DCR1 in modulating the biological characteristics of dual-species biofilms of S. mutans and C. albicans and to reveal the molecular mechanism of regulation. The morphology, biomass, EPS content, and lactic acid production of the dual-species biofilm were assessed. Quantitative real-time polymerase chain reaction (qRT-PCR) and transcriptomic profiling were performed to unravel the alteration of C. albicans virulence. We found that both rnc and DCR1 could regulate the biological traits of cross-kingdom biofilms. The rnc gene prominently contributed to the formation of dual-species biofilms by positively modulating the extracellular polysaccharide synthesis, leading to increased biomass, biofilm roughness, and acid production. Changes in the microecological system probably impacted the virulence as well as polysaccharide or pyruvate metabolism pathways of C. albicans, which facilitated the assembly of a cariogenic cross-kingdom biofilm and the generation of an augmented acidic milieu. These results may provide an avenue for exploring new targets for the effective prevention and treatment of ECC.
Collapse
Affiliation(s)
- Yangyu Lu
- State Key Laboratory of Oral Diseases, Department of Preventive Dentistry, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Guangdong Provincial Key Laboratory of Stomatology, Department of Operative Dentistry and Endodontics, Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Lei Lei
- State Key Laboratory of Oral Diseases, Department of Preventive Dentistry, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yalan Deng
- State Key Laboratory of Oral Diseases, Department of Preventive Dentistry, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Hongyu Zhang
- State Key Laboratory of Oral Diseases, Department of Preventive Dentistry, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Mengying Xia
- State Key Laboratory of Oral Diseases, Department of Preventive Dentistry, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xi Wei
- Guangdong Provincial Key Laboratory of Stomatology, Department of Operative Dentistry and Endodontics, Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Yingming Yang
- State Key Laboratory of Oral Diseases, Department of Preventive Dentistry, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- *Correspondence: Yingming Yang,
| | - Tao Hu
- State Key Laboratory of Oral Diseases, Department of Preventive Dentistry, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Tao Hu,
| |
Collapse
|
2
|
Yan H, Huang J, Zhang H, Shim WB. A Rab GTPase protein FvSec4 is necessary for fumonisin B1 biosynthesis and virulence in Fusarium verticillioides. Curr Genet 2019; 66:205-216. [PMID: 31292685 DOI: 10.1007/s00294-019-01013-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 06/30/2019] [Accepted: 07/01/2019] [Indexed: 10/26/2022]
Abstract
Rab GTPases are responsible for a variety of membrane trafficking and vesicular transportation in fungi. But the role of Rab GTPases in Fusarium verticillioides, one of the key corn pathogens worldwide, remains elusive. These Small GTPases in fungi, particularly those homologous to Saccharomyces cerevisiae Sec4, are known to be associated with protein secretion, vesicular trafficking, secondary metabolism and pathogenicity. In this study, our aim was to investigate the molecular functions of FvSec4 in F. verticillioides associated with physiology and virulence. Interestingly, the FvSec4 null mutation did not impair the expression of key conidiation-related genes. Also, the mutant did not show any defect in sexual development, including perithecia production. Meanwhile, GFP-FvSec4 localized to growing hyphal tips and raised the possibility that FvSec4 is involved in protein trafficking and endocytosis. The mutant exhibited defect in corn stalk rot virulence and also significant alteration of fumonisin B1 production. The mutation led to higher sensitivity to oxidative and cell wall stress agents, and defects in carbon utilization. Gene complementation fully restored the defects in the mutant demonstrating that FvSec4 plays important roles in these functions. Taken together, our data indicate that FvSec4 is critical in F. verticillioides hyphal development, virulence, mycotoxin production and stress responses.
Collapse
Affiliation(s)
- Huijuan Yan
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, 77843, USA
| | - Jun Huang
- Department of Plant Pathology, Kansas State University, Manhattan, KS, 66506, USA
| | - Huan Zhang
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Won Bo Shim
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, 77843, USA.
| |
Collapse
|
3
|
Weiner A, Orange F, Lacas‐Gervais S, Rechav K, Ghugtyal V, Bassilana M, Arkowitz RA. On‐site secretory vesicle delivery drives filamentous growth in the fungal pathogenCandida albicans. Cell Microbiol 2018; 21:e12963. [DOI: 10.1111/cmi.12963] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 10/02/2018] [Accepted: 10/04/2018] [Indexed: 12/31/2022]
Affiliation(s)
- Allon Weiner
- Université Côte d'AzurCNRS, Inserm, Institute of Biology Valrose Parc Valrose Nice France
| | | | | | - Katya Rechav
- Chemical Research SupportWeizmann Institute of Science Rehovot Israel
| | - Vikram Ghugtyal
- Université Côte d'AzurCNRS, Inserm, Institute of Biology Valrose Parc Valrose Nice France
| | - Martine Bassilana
- Université Côte d'AzurCNRS, Inserm, Institute of Biology Valrose Parc Valrose Nice France
| | - Robert A. Arkowitz
- Université Côte d'AzurCNRS, Inserm, Institute of Biology Valrose Parc Valrose Nice France
| |
Collapse
|
4
|
Hua L, Yong C, Zhanquan Z, Boqiang L, Guozheng Q, Shiping T. Pathogenic mechanisms and control strategies of Botrytis cinerea causing post-harvest decay in fruits and vegetables. FOOD QUALITY AND SAFETY 2018. [DOI: 10.1093/fqsafe/fyy016] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Li Hua
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing
- University of Chinese Academy of Sciences, Beijing
| | - Chen Yong
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing
- University of Chinese Academy of Sciences, Beijing
| | - Zhang Zhanquan
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing
- Key Laboratory of Post-Harvest Handing of Fruits, Ministry of Agriculture of China, Institute of Botany, Chinese Academy of Sciences, China
| | - Li Boqiang
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing
- Key Laboratory of Post-Harvest Handing of Fruits, Ministry of Agriculture of China, Institute of Botany, Chinese Academy of Sciences, China
| | - Qin Guozheng
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing
- Key Laboratory of Post-Harvest Handing of Fruits, Ministry of Agriculture of China, Institute of Botany, Chinese Academy of Sciences, China
| | - Tian Shiping
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing
- University of Chinese Academy of Sciences, Beijing
- Key Laboratory of Post-Harvest Handing of Fruits, Ministry of Agriculture of China, Institute of Botany, Chinese Academy of Sciences, China
| |
Collapse
|
5
|
Guo M, Kilaru S, Schuster M, Latz M, Steinberg G. Fluorescent markers for the Spitzenkörper and exocytosis in Zymoseptoria tritici. Fungal Genet Biol 2016; 79:158-65. [PMID: 26092802 PMCID: PMC4502456 DOI: 10.1016/j.fgb.2015.04.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 04/10/2015] [Accepted: 04/13/2015] [Indexed: 11/25/2022]
Abstract
We establish Z. tritici polarity markers ZtSec4, ZtMlc1, ZtRab11, ZtExo70 and ZtSpa2. All markers localize correctly, labeling the Spitzenkörper and sites of polar exocytosis. We provide 5 carboxin-resistance conveying vectors for integration of all markers into the sdi1 locus. We provide 5 hygromycin B-resistance conveying vectors for random integration of all markers.
Fungal hyphae are highly polarized cells that invade their substrate by tip growth. In plant pathogenic fungi, hyphal growth is essential for host invasion. This makes polarity factors and secretion regulators potential new targets for novel fungicides. Polarization requires delivery of secretory vesicles to the apical Spitzenkörper, followed by polarized exocytosis at the expanding cell tip. Here, we introduce fluorescent markers to visualize the apical Spitzenkörper and the apical site of exocytosis in hyphae of the wheat pathogen Zymoseptoria tritici. We fused green fluorescent protein to the small GTPase ZtSec4, the myosin light chain ZtMlc1 and the small GTPase ZtRab11 and co-localize the fusion proteins with the dye FM4-64 in the hyphal apex, suggesting that the markers label the hyphal Spitzenkörper in Z. tritici. In addition, we localize GFP-fusions to the exocyst protein ZtExo70, the polarisome protein ZtSpa2. Consistent with results in the ascomycete Neurospora crassa, these markers did localize near the plasma membrane at the hyphal tip and only partially co-localize with FM4-64. Thus, these fluorescent markers are useful molecular tools that allow phenotypic analysis of mutants in Z. tritici. These tools will help develop new avenues of research in our quest to control STB infection in wheat.
Collapse
Affiliation(s)
- M Guo
- School of Biosciences, University of Exeter, Exeter EX4 4QD, UK
| | - S Kilaru
- School of Biosciences, University of Exeter, Exeter EX4 4QD, UK
| | - M Schuster
- School of Biosciences, University of Exeter, Exeter EX4 4QD, UK
| | - M Latz
- School of Biosciences, University of Exeter, Exeter EX4 4QD, UK
| | - G Steinberg
- School of Biosciences, University of Exeter, Exeter EX4 4QD, UK.
| |
Collapse
|
6
|
Zheng H, Chen S, Chen X, Liu S, Dang X, Yang C, Giraldo MC, Oliveira-Garcia E, Zhou J, Wang Z, Valent B. The Small GTPase MoSec4 Is Involved in Vegetative Development and Pathogenicity by Regulating the Extracellular Protein Secretion in Magnaporthe oryzae. FRONTIERS IN PLANT SCIENCE 2016; 7:1458. [PMID: 27729922 PMCID: PMC5037964 DOI: 10.3389/fpls.2016.01458] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Accepted: 09/12/2016] [Indexed: 05/18/2023]
Abstract
The Rab GTPase proteins play important roles in the membrane trafficking, and consequently protein secretion and development of eukaryotic organisms. However, little is known about the function of Rab GTPases in Magnaporthe oryzae. To further explore the function of Rab GTPases, we deleted the ortholog of the yeast Sec4p protein in M. oryzae, namely MoSEC4. The ΔMosec4 mutant is defective in polarized growth and conidiation, and it displays decreased appressorium turgor pressure and attenuated pathogenicity. Notably, the biotrophic invasive hyphae produced in rice cells are more bulbous and compressed in the ΔMosec4 mutant. Further studies showed that deletion of the MoSEC4 gene resulted in decreased secretion of extracellular enzymes and mislocalization of the cytoplasmic effector PWL2-mCherry-NLS. In accordance with a role in secretion, the GFP-MoSec4 fusion protein mainly accumulates at tips of growing vegetative hyphae. Our results suggest that the MoSec4 protein plays important roles in the secretion of extracellular proteins and consequently hyphal development and pathogenicity in the rice blast fungus.
Collapse
Affiliation(s)
- Huakun Zheng
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry UniversityFuzhou, China
- Department of Plant Pathology, Kansas State UniversityManhattan, KS, USA
- Basic Forestry and Proteomics Research Center, Haixia Institute of Science and Technology (HIST), Fujian Agriculture and Forestry UniversityFuzhou, China
| | - Simiao Chen
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry UniversityFuzhou, China
| | - Xiaofeng Chen
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry UniversityFuzhou, China
| | - Shuyan Liu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry UniversityFuzhou, China
| | - Xie Dang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry UniversityFuzhou, China
| | - Chengdong Yang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry UniversityFuzhou, China
| | - Martha C. Giraldo
- Department of Plant Pathology, Kansas State UniversityManhattan, KS, USA
| | | | - Jie Zhou
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry UniversityFuzhou, China
- *Correspondence: Jie Zhou
| | - Zonghua Wang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry UniversityFuzhou, China
- Basic Forestry and Proteomics Research Center, Haixia Institute of Science and Technology (HIST), Fujian Agriculture and Forestry UniversityFuzhou, China
- Zonghua Wang
| | - Barbara Valent
- Department of Plant Pathology, Kansas State UniversityManhattan, KS, USA
- Barbara Valent
| |
Collapse
|
7
|
Chen X, Ebbole DJ, Wang Z. The exocyst complex: delivery hub for morphogenesis and pathogenesis in filamentous fungi. CURRENT OPINION IN PLANT BIOLOGY 2015; 28:48-54. [PMID: 26453967 DOI: 10.1016/j.pbi.2015.09.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Revised: 08/30/2015] [Accepted: 09/05/2015] [Indexed: 06/05/2023]
Abstract
Regulated by several small GTPases, the octameric exocyst complex directs the docking and tethering of exocytic vesicles to the destined plasma membrane sites, providing the precise spatiotemporal control of exocytosis. Although the exocyst components are well conserved among various fungal species, the mechanisms for the regulation of its assembly and activity are diverse. Exocytosis is crucial for the generation of cell polarity as well as the delivery of effector proteins in filamentous fungi, and thus plays an important role for fungal morphogenesis and pathogenicity on plant hosts. This review focuses on current findings about the roles of the exocyst complex in the morphogenesis and pathogenesis of filamentous fungi.
Collapse
Affiliation(s)
- Xiaofeng Chen
- Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fujian Agriculture and Forestry University, Fuzhou 350002, China; Fujian Province Key Laboratory of Pathogenic Fungi and Mycotoxins, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Daniel J Ebbole
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843, USA
| | - Zonghua Wang
- Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fujian Agriculture and Forestry University, Fuzhou 350002, China; Fujian Province Key Laboratory of Pathogenic Fungi and Mycotoxins, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| |
Collapse
|
8
|
Rane HS, Hardison S, Botelho C, Bernardo SM, Wormley F, Lee SA. Candida albicans VPS4 contributes differentially to epithelial and mucosal pathogenesis. Virulence 2014; 5:810-8. [PMID: 25483774 DOI: 10.4161/21505594.2014.956648] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We have previously demonstrated that the C. albicans pre-vacuolar protein sorting gene VPS4 is required for extracellular secretion of the secreted aspartyl proteases Sap2p and Saps4-6p. Furthermore, the vps4Δ null mutant has been shown to be markedly hypovirulent in a murine tail vein model of disseminated candidiasis. In these experiments, we sought to further define the role of the pre-vacuolar secretion pathway mediated by the pre-vacuolar sorting gene VPS4 in the pathogenesis of epithelial and mucosal infection using a broad range of virulence models. The C. albicans vps4Δ mutant demonstrates reduced tolerance of cell wall stresses compared to its isogenic, complemented control strain. In an in vitro oral epithelial model (OEM) of tissue invasion, the vps4Δ mutant caused reduced tissue damage compared to controls. Further, the vps4Δ mutant was defective in macrophage killing in vitro, and was attenuated in virulence in an in vivo Caenorhabditis elegans model representative of intestinal epithelial infection. In contrast, the vps4Δ mutant caused a similar degree of tissue damage in an in vitro uroepithelial model of Candida infection compared with controls. Furthermore, in an in vivo murine model of vaginal candidiasis there was no reduction in fungal colony burden and no differences in vaginal histopathology compared to wild-type and complemented controls. These results suggest that VPS4 contributes to several key aspects of oral epithelial but not uroepithelial infection, and in contrast to systemic infection, plays no major role in the pathogenesis of Candida vaginitis. By using a wide range of virulence models, we demonstrate that C. albicans VPS4 contributes to virulence according to the specific tissue that is infected. Thus, in order to gain a full understanding of C. albicans virulence in relation to a particular gene or pathway of interest, a selected range of infection models may need to be utilized.
Collapse
Affiliation(s)
- Hallie S Rane
- a Division of Infectious Diseases ; University of New Mexico Health Science Center ; Albuquerque , NM USA
| | | | | | | | | | | |
Collapse
|
9
|
Zhang Z, Qin G, Li B, Tian S. Knocking out Bcsas1 in Botrytis cinerea impacts growth, development, and secretion of extracellular proteins, which decreases virulence. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2014; 27:590-600. [PMID: 24520899 DOI: 10.1094/mpmi-10-13-0314-r] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Pathogenic fungi usually secrete a series of virulence factors to the extracellular environment to facilitate infection. Rab GTPases play a central role in the secretory pathway. To explore the function of Rab/GTPase in filamentous fungi, we knocked out a Rab/GTPase family gene, Bcsas1, in Botrytis cinerea, an aggressive fungal pathogen that infects more than 200 plant species. A detailed analysis was conducted on the virulence and the secretory capability of the mutants. The results indicated that knockout of Bcsas1 inhibited hyphal development and reduced sporulation of B. cinerea on potato dextrose agar plates resulting in reduced virulence on various fruit hosts. Knocking out the Bcsas1 gene led to an accumulation of transport vesicles at the hyphal tip, significantly reduced extracellular protein content, and lowered the activity of polygalacturonase and xylanase in the extracellular medium. However, mutation of Bcsas1 did not affect the expression of genes encoding polygalacturonase and xylanase, suggesting the secretion of these two family enzymes was suppressed in the mutant. Moreover, a comparative analysis of the secretome provided further evidence that the disruption of Bcsas1 in mutant strains significantly depressed the secretion of polysaccharide hydrolases and proteases. The results indicate that Bcsas1, the Rab8/SEC4-like gene, plays a crucial role in development, protein secretion, and virulence of B. cinerea.
Collapse
|
10
|
Powers-Fletcher MV, Feng X, Krishnan K, Askew DS. Deletion of the sec4 homolog srgA from Aspergillus fumigatus is associated with an impaired stress response, attenuated virulence and phenotypic heterogeneity. PLoS One 2013; 8:e66741. [PMID: 23785510 PMCID: PMC3681910 DOI: 10.1371/journal.pone.0066741] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 05/10/2013] [Indexed: 01/04/2023] Open
Abstract
Small GTPases of the Rab family are master regulators of membrane trafficking, responsible for coordinating the sorting, packaging and delivery of membrane-bound vesicles to specific sites within eukaryotic cells. The contribution of these proteins to the biology of the human pathogenic fungus Aspergillus fumigatus has not been explored. In this study, we characterized the srgA gene, encoding a Rab GTPase closely related to Sec4. We found that a GFP-SrgA fusion protein accumulated preferentially at hyphal tips and mature condiophores. The radial growth of a ΔsrgA mutant was impaired on both rich and minimal medium, consistent with a role for SrgA in filamentous growth. In addition, the ΔsrgA mutant revealed dysmorphic conidiophores that produced conidia with heterogeneous morphology. The ΔsrgA mutant was hypersensitive to brefeldin A-mediated inhibition of vesicular trafficking and showed increased temperature sensitivity relative to wild type A. fumigatus. However, the most striking phenotype of this mutant was its phenotypic heterogeneity. Individual colonies isolated from the original ΔsrgA mutant showed variable morphology with colony sectoring. In addition, each isolate of the ΔsrgA mutant displayed divergent phenotypes with respect to thermotolerance, in vitro stress response and virulence in a Galleria mellonella infection model. Taken together, these results indicate that SrgA contributes to the asexual development and filamentous growth of A. fumigatus. However, the discordant phenotypes observed among individual isolates of the ΔsrgA mutant suggest that the absence of srgA exerts selective pressure for the acquisition of compensatory changes, such as second-site suppressor mutations.
Collapse
Affiliation(s)
- Margaret V. Powers-Fletcher
- Department of Pathology & Laboratory Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Xizhi Feng
- Department of Pathology & Laboratory Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Karthik Krishnan
- Department of Pathology & Laboratory Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - David S. Askew
- Department of Pathology & Laboratory Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
- * E-mail:
| |
Collapse
|
11
|
Rostagno L, Prodi A, Turina M. Cpkk1, MAPKK of Cryphonectria parasitica, is necessary for virulence on chestnut. PHYTOPATHOLOGY 2010; 100:1100-1110. [PMID: 20839945 DOI: 10.1094/phyto-02-10-0044] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
ABSTRACT The role of Cpkk1, a mitogen-activated protein kinase from Cryphonectria parasitica, was investigated by generating a number of mutant strains that overexpress, under the control of the cryparin promoter, both the wild-type protein and its allele with an extensive deletion in the catalytic domain. Furthermore, a hairpin construct was built and expressed to cause specific silencing of Cpkk1 mRNA transcripts. Specific mRNA silencing or overexpression was confirmed on both Northern and Western blot analysis. Selected C. parasitica strains with Cpkk1 either silenced or overexpressed were evaluated for their biological characteristics, including virulence on European chestnut, growth on different substrates, conidial sporulation, and resistance to cell-wall-degrading enzymes. Silencing of Cpkk1 and the overexpression of a defective Cpkk1 correlated with a marked reduction in virulence on 3-year-old chestnut trees, with no statistically significant effect on fungal growth in the various conditions tested.
Collapse
|
12
|
The Candida albicans Kar2 protein is essential and functions during the translocation of proteins into the endoplasmic reticulum. Curr Genet 2010; 57:25-37. [PMID: 20886215 DOI: 10.1007/s00294-010-0323-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 09/10/2010] [Accepted: 09/12/2010] [Indexed: 01/12/2023]
Abstract
Since the secretory pathway is essential for Candida albicans to transition from a commensal organism to a pathogen, an understanding of how this pathway functions may be beneficial for identifying novel drug targets to prevent candidiasis. We have cloned the C. albicans KAR2 gene, which performs many roles during the translocation of proteins into the endoplasmic reticulum (ER) during the first committed step of the secretory pathway in many eukaryotes. Our results show that C. albicans KAR2 is essential, and that the encoded protein rescues a temperature-sensitive growth defect found in a Saccharomyces cerevisiae strain harboring a mutant form of the Kar2 protein. Additionally, S. cerevisiae containing CaKAR2 as the sole copy of this essential gene are viable, and ER microsomes prepared from this strain exhibit wild-type levels of post-translational translocation during in vitro translocation assays. Finally, ER microsomes isolated from a C. albicans strain expressing reduced amounts of KAR2 mRNA are defective for in vitro translocation of a secreted substrate protein, establishing a new method to study ER translocation in this organism. Together, these results suggest that C. albicans Kar2p functions during the translocation of proteins into the ER during the first step of the secretory pathway.
Collapse
|
13
|
Basso LR, Bartiss A, Mao Y, Gast CE, Coelho PSR, Snyder M, Wong B. Transformation of Candida albicans with a synthetic hygromycin B resistance gene. Yeast 2010; 27:1039-48. [PMID: 20737428 DOI: 10.1002/yea.1813] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Accepted: 07/11/2010] [Indexed: 11/07/2022] Open
Abstract
Synthetic genes that confer resistance to the antibiotic nourseothricin in the pathogenic fungus Candida albicans are available, but genes conferring resistance to other antibiotics are not. We found that multiple C. albicans strains were inhibited by hygromycin B, so we designed a 1026 bp gene (CaHygB) that encodes Escherichia coli hygromycin B phosphotransferase with C. albicans codons. CaHygB conferred hygromycin B resistance in C. albicans transformed with ars2-containing plasmids or single-copy integrating vectors. Since CaHygB did not confer nourseothricin resistance and since the nourseothricin resistance marker SAT-1 did not confer hygromycin B resistance, we reasoned that these two markers could be used for homologous gene disruptions in wild-type C. albicans. We used PCR to fuse CaHygB or SAT-1 to approximately 1 kb of 5' and 3' noncoding DNA from C. albicans ARG4, HIS1 and LEU2, and introduced the resulting amplicons into six wild-type C. albicans strains. Homologous targeting frequencies were approximately 50-70%, and disruption of ARG4, HIS1 and LEU2 alleles was verified by the respective transformants' inabilities to grow without arginine, histidine and leucine. CaHygB should be a useful tool for genetic manipulation of different C. albicans strains, including clinical isolates.
Collapse
Affiliation(s)
- Luiz R Basso
- Division of Infectious Diseases, Department of Medicine, Oregon Health and Science University, Portland, OR 97239-0398, USA
| | | | | | | | | | | | | |
Collapse
|
14
|
Fluconazole transport into Candida albicans secretory vesicles by the membrane proteins Cdr1p, Cdr2p, and Mdr1p. EUKARYOTIC CELL 2010; 9:960-70. [PMID: 20348384 DOI: 10.1128/ec.00355-09] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A major cause of azole resistance in Candida albicans is overexpression of CDR1, CDR2, and/or MDR1, which encode plasma membrane efflux pumps. To analyze the catalytic properties of these pumps, we used ACT1- and GAL1-regulated expression plasmids to overexpress CDR1, CDR2, or MDR1 in a C. albicans cdr1 cdr2 mdr1-null mutant. When the genes of interest were expressed, the resulting transformants were more resistant to multiple azole antifungals, and accumulated less [(3)H]fluconazole intracellularly, than empty-vector controls. Next, we used a GAL1-regulated dominant negative sec4 allele to cause cytoplasmic accumulation of post-Golgi secretory vesicles (PGVs), and we found that PGVs isolated from CDR1-, CDR2-, or MDR1-overexpressing cells accumulated much more [(3)H]fluconazole than did PGVs from empty-vector controls. The K(m)s (expressed in micromolar concentrations) and V(max)s (expressed in picomoles per milligram of protein per minute), respectively, for [(3)H]fluconazole transport were 0.8 and 0.91 for Cdr1p, 4.3 and 0.52 for Cdr2p, and 3.5 and 0.59 for Mdr1p. [(3)H]fluconazole transport by Cdr1p and Cdr2p required ATP and was unaffected by carbonyl cyanide 3-chlorophenylhydrazone (CCCP), whereas [(3)H]fluconazole transport by Mdr1p did not require ATP and was inhibited by CCCP. [(3)H]fluconazole uptake by all 3 pumps was inhibited by all other azoles tested, with 50% inhibitory concentrations (IC(50)s; expressed as proportions of the [(3)H]fluconazole concentration) of 0.2 to 5.6 for Cdr1p, 0.3 to 3.1 for Cdr2p, and 0.3 to 3.1 for Mdr1p. The methods used in this study may also be useful for studying other plasma membrane transporters in C. albicans and other medically important fungi.
Collapse
|
15
|
|
16
|
Candida albicans VPS4 is required for secretion of aspartyl proteases and in vivo virulence. Mycopathologia 2008; 167:55-63. [PMID: 18814053 DOI: 10.1007/s11046-008-9155-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Accepted: 09/02/2008] [Indexed: 11/27/2022]
Abstract
Candida albicans secretes aspartyl proteases (Saps) during infection. Although Saps are secretory proteins, little is known about the intracellular trafficking and secretion of these proteins. We previously cloned and analyzed the C. albicans pre-vacuolar protein sorting gene VPS4, and demonstrated that extracellular Sap2p is absent in the culture supernatants of the vps4delta null mutant. We therefore investigated the role of the C. albicans pre-vacuolar secretion pathway in the trafficking of Sap4-6p and in vivo virulence. The C. albicans vps4delta mutant failed to produce extracellular Sap4-6p. Next, when tested in a mouse model of disseminated candidiasis, the vps4delta mutant was greatly attenuated in virulence. Histopathological analysis indicated that infection with the vps4delta mutant did not cause renal microabscess formation, in contrast to the wild-type strain. Our results imply that VPS4 is required for extracellular secretion of Sap4-6p, and that C. albicans requires an intact pre-vacuolar secretory pathway for wild-type virulence in vivo.
Collapse
|
17
|
Yoneda A, Doering TL. A eukaryotic capsular polysaccharide is synthesized intracellularly and secreted via exocytosis. Mol Biol Cell 2006; 17:5131-40. [PMID: 17021252 PMCID: PMC1679678 DOI: 10.1091/mbc.e06-08-0701] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Cryptococcus neoformans, which causes fatal infection in immunocompromised individuals, has an elaborate polysaccharide capsule surrounding its cell wall. The cryptococcal capsule is the major virulence factor of this fungal organism, but its biosynthetic pathways are virtually unknown. Extracellular polysaccharides of eukaryotes may be made at the cell membrane or within the secretory pathway. To test these possibilities for cryptococcal capsule synthesis, we generated a secretion mutant in C. neoformans by mutating a Sec4/Rab8 GTPase homolog. At a restrictive temperature, the mutant displayed reduced growth and protein secretion, and accumulated approximately 100-nm vesicles in a polarized manner. These vesicles were not endocytic, as shown by their continued accumulation in the absence of polymerized actin, and could be labeled with anti-capsular antibodies as visualized by immunoelectron microscopy. These results indicate that glucuronoxylomannan, the major cryptococcal capsule polysaccharide, is trafficked within post-Golgi secretory vesicles. This strongly supports the conclusion that cryptococcal capsule is synthesized intracellularly and secreted via exocytosis.
Collapse
Affiliation(s)
- Aki Yoneda
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Tamara L. Doering
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110
| |
Collapse
|
18
|
Lee SA, Khalique Z, Gale CA, Wong B. Intracellular trafficking of fluorescently tagged proteins associated with pathogenesis in Candida albicans. Med Mycol 2005; 43:423-30. [PMID: 16178371 DOI: 10.1080/13693780400013340] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Proteins that enter the secretory pathway play important roles in virulence and pathogenesis in Candida albicans, but our understanding of the trafficking of these proteins is in its early stages. In Saccharomyces cerevisiae, dominant negative alleles of YPT1 and SEC4 interrupt secretory traffic at pre- and post-Golgi steps, respectively. We therefore used a dominant negative genetic approach to examine the intracellular trafficking of several proteins associated with virulence or azole resistance. When the dominant negative ypt1(N121I) allele of C. albicans was overexpressed, yellow-fluorescent protein (YFP) tagged forms of two plasma membrane transporters (Cdrlp and Ftrlp) and the vacuolar membrane ABC transporter Mltlp accumulated in intracellular structures that appeared related to the ER, but localization of Cdc10p and Int1p was unaffected. When the dominant negative sec4(S28N) allele of C. albicans was overexpressed, Cdrlp and Ftrlp accumulated intracellularly, and localization of Mltlp, Cdc10p and Int1p was unaffected. These results imply that (i) Cdrlp and Ftrlp are transported to the plasma membrane by the general secretory pathway, (ii) Mlt1p enters the secretory pathway but is diverted to the vacuole at an early post-Golgi step, and (iii) like Cdc10p, Int1p does not enter the general secretory pathway.
Collapse
Affiliation(s)
- Samuel A Lee
- Infectious Diseases Section, Yale University School of Medicine, New Haven, Connecticut, USA
| | | | | | | |
Collapse
|
19
|
Liu SH, Chou WI, Lin SC, Sheu CC, Chang MDT. Molecular genetic manipulation of Pichia pastoris SEC4 governs cell growth and glucoamylase secretion. Biochem Biophys Res Commun 2005; 336:1172-80. [PMID: 16176807 DOI: 10.1016/j.bbrc.2005.08.234] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2005] [Accepted: 08/29/2005] [Indexed: 11/28/2022]
Abstract
We have previously engineered a recombinant Pichia pastoris GS115 transformant, MSPGA-7, harboring seven copies of glucoamylase (GA) fused with modified signal peptide. High yield secretion of GA was achieved as an extra copy of SEC4 was integrated to the transformant. To elucidate the physiological role of SEC4, a dominant-negative mutant of SEC4, SEC4(S28N), was overexpressed under the control of alchohol oxidase 1 (AOX1) promoter in P. pastoris strain MSPGA-7 as well as a set of host cells harboring multi-copy of wild type SEC4. We found that SEC4(S28N) mutation in the key guanine nucleotide binding domain reduced guanine nucleotide binding affinity, hence it blocked the transport of vesicles required for targeting and fusion to the plasma membrane. The inhibitory levels of cell growth and GA secretion were correlated with the dosage of SEC4(S28N) gene. In addition, overexpression of SEC4 driven by AOX1 promoter in MSPGA-7 improved the secretory production of GA, but demonstrated the delay of cell growth by increased gene dosage of SEC4. Interestingly, a limited level of Sec4p did not disturb the cell growth. It was because expression of only one copy of SEC4 resulted in delay of cell growth at an early stage while still maintaining high level Sec4p at long-term incubation. Accordingly, as glyceraldehyde-3-phosphate dehydrogenase promoter was used to substitute AOX1 promoter to drive the SEC4 expression, enhanced GA secretion but not inhibition of cell growth was achieved. Taken together, our results demonstrate that SEC4 is essential for P. pastoris in regulating cell growth and heterologous protein secretion in a dosage-dependent manner.
Collapse
Affiliation(s)
- Shi-Hwei Liu
- Institute of Molecular and Cellular Biology, Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan 30013, ROC
| | | | | | | | | |
Collapse
|
20
|
Siriputthaiwan P, Jauneau A, Herbert C, Garcin D, Dumas B. Functional analysis of CLPT1, a Rab/GTPase required for protein secretion and pathogenesis in the plant fungal pathogen Colletotrichum lindemuthianum. J Cell Sci 2004; 118:323-9. [PMID: 15615776 DOI: 10.1242/jcs.01616] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In eukaryotic cells, Rab/GTPases are major regulators of vesicular trafficking and are involved in essential processes including exocytosis, endocytosis and cellular differentiation. To investigate the role of these proteins in fungal pathogenicity, a dominant-negative mutant allele of CLPT1, a Rab/GTPase of the bean pathogen Colletotrichum lindemuthianum, was expressed in transgenic strains. This mutated gene encodes the amino-acid substitution N123I analogous to the N133I substitution in a known trans-dominant inhibitor of the Sec4 Rab/GTPase from Saccharomyces cerevisiae. A pectinase gene promoter was used to drive the CLPT1(N123I) allele in C. lindemuthianum, allowing the expression of the foreign gene on pectin medium and during pathogenesis, but not on glucose. The same strategy was used to overexpress the wild-type CLPT1 allele. During growth on pectin medium, production of extracellular pectinases was strongly impaired only in CLPT1(N123I)-expressing strains. Cytological analysis revealed that CLPT1(N123I) strains accumulated intracellular aggregates only on pectin, resulting from the fusion of vesicles containing polysaccharides or glycoproteins. Moreover, these strains showed a severe reduction of pathogenesis and were unable to penetrate the host cells. These results indicated that the Rab/GTPase CLPT1 is essential for fungal pathogenesis by regulating the intracellular transport of secretory vesicles involved in the delivery of proteins to the extracellular medium and differentiation of infectious structures.
Collapse
|
21
|
de la Rosa JM, Ruiz T, Fonzi WA, Rodríguez L. Analysis of heterologous expression of Candida albicans SEC61 gene reveals differences in Sec61p homologues related to species-specific functionality. Fungal Genet Biol 2004; 41:941-53. [PMID: 15341916 DOI: 10.1016/j.fgb.2004.07.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2004] [Accepted: 07/13/2004] [Indexed: 10/26/2022]
Abstract
The protein secretory pathway has not been studied in depth in Candida albicans despite its essential role in the secretion of enzymes and cell surface components related to the ability of the fungus to colonize the human host. To gain further insight into the elements that participate in the first stages of the secretory process in this fungal pathogen we have isolated and characterized the C. albicans ortholog of SEC61. In other species SEC61 has been shown to encode the core element of the protein translocation apparatus within the ER membrane. The cloned gene appears to be essential for cell viability and encodes a highly conserved protein, very similar to the Sec61p from other yeast species both in sequence and hydropathy profile. However, CaSec61p is not able to complement the thermosensitive-growth phenotype of a Saccharomyces cerevisiae sec61 mutant, even though it is expressed and correctly incorporated into the ER membrane of the transformant cells. We report results indicating that the lack of functional complementation could be related to differences in the primary structure of the cytosolic domain located between the fourth and fifth transmembrane domains of the accepted topological model of Sec61p.
Collapse
Affiliation(s)
- José M de la Rosa
- Departamento de Microbiología y Biología Celular, Facultad de Farmacia, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain
| | | | | | | |
Collapse
|
22
|
Mao Y, Zhang Z, Wong B. Use of green fluorescent protein fusions to analyse the N- and C-terminal signal peptides of GPI-anchored cell wall proteins in Candida albicans. Mol Microbiol 2004; 50:1617-28. [PMID: 14651643 DOI: 10.1046/j.1365-2958.2003.03794.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Glycophosphatidylinositol (GPI)-anchored proteins account for 26-35% of the Candida albicans cell wall. To understand the signals that regulate these proteins' cell surface localization, green fluorescent protein (GFP) was fused to the N- and C-termini of the C. albicans cell wall proteins (CWPs) Hwp1p, Als3p and Rbt5p. C. albicans expressing all three fusion proteins were fluorescent at the cell surface. GFP was released from membrane fractions by PI-PLC and from cell walls by beta-glucanase, which implied that GFP was GPI-anchored to the plasma membrane and then covalently attached to cell wall glucans. Twenty and 25 amino acids, respectively, from the N- and C-termini of Hwp1p were sufficient to target GFP to the cell surface. C-terminal substitutions that are permitted by the omega rules (G613D, G613N, G613S, G613A, G615S) did not interfere with GFP localization, whereas some non-permitted substitutions (G613E, G613Q, G613R, G613T and G615Q) caused GFP to accumulate in intracellular ER-like structures and others (G615C, G613N/G615C and G613D/G615C) did not. These results imply that (i) GFP fusions can be used to analyse the N- and C-terminal signal peptides of GPI-anchored CWPs, (ii) the omega amino acid in Hwp1p is G613, and (iii) C can function at the omega+2 position in C. albicans GPI-anchored proteins.
Collapse
Affiliation(s)
- Yuxin Mao
- Infectious Diseases Section, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA
| | | | | |
Collapse
|
23
|
Gupta GD, Free SJ, Levina NN, Keränen S, Heath IB. Two divergent plasma membrane syntaxin-like SNAREs, nsyn1 and nsyn2, contribute to hyphal tip growth and other developmental processes in Neurospora crassa. Fungal Genet Biol 2004; 40:271-86. [PMID: 14599895 DOI: 10.1016/s1087-1845(03)00109-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Highly polarized exocytosis of vesicles at hyphal apices is an essential requirement of tip growth. This requirement may be met by the localization and/or activation of an apical SNARE-based machinery. We have cloned nsyn1 and nsyn2, SNAREs predicted to function at the plasma membrane in Neurospora crassa. Transformation of extra copies of nsyn1 into wild-type strains displayed effects consistent with quelling of nsyn1 expression, which was lethal in most transformants. All surviving transformants grew slowly, conidiated poorly, and were male sterile. In addition, antisense nsyn1 strains grew slowly, with abnormal hyphal diameters and polarity and defective conidiation. For nsyn2, several repeat induced point mutation (RIP) crosses produced no, or poorly germinating ascospores. Those that germinated produced slow-growing hyphae with abnormal branching. The defects in nsyn1 and nsyn2 mutants are consistent with differential impaired vesicle fusion in hyphal tips and other developmental stages.
Collapse
Affiliation(s)
- Gagan D Gupta
- Department of Biology, York University, 4700 Keele Street, Ont., M3J1P3, Toronto, Canada.
| | | | | | | | | |
Collapse
|
24
|
Lee SA, Wormsley S, Kamoun S, Lee AFS, Joiner K, Wong B. An analysis of the Candida albicans genome database for soluble secreted proteins using computer-based prediction algorithms. Yeast 2003; 20:595-610. [PMID: 12734798 DOI: 10.1002/yea.988] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
We sought to identify all genes in the Candida albicans genome database whose deduced proteins would likely be soluble secreted proteins (the secretome). While certain C. albicans secretory proteins have been studied in detail, more data on the entire secretome is needed. One approach to rapidly predict the functions of an entire proteome is to utilize genomic database information and prediction algorithms. Thus, we used a set of prediction algorithms to computationally define a potential C. albicans secretome. We first assembled a validation set of 47 C. albicans proteins that are known to be secreted and 47 that are known not to be secreted. The presence or absence of an N-terminal signal peptide was correctly predicted by SignalP version 2.0 in 47 of 47 known secreted proteins and in 47 of 47 known non-secreted proteins. When all 6165 C. albicans ORFs from CandidaDB were analysed with SignalP, 495 ORFs were predicted to encode proteins with N-terminal signal peptides. In the set of 495 deduced proteins with N-terminal signal peptides, 350 were predicted to have no transmembrane domains (or a single transmembrane domain at the extreme N-terminus) and 300 of these were predicted not to be GPI-anchored. TargetP was used to eliminate proteins with mitochondrial targeting signals, and the final computationally-predicted C. albicans secretome was estimated to consist of up to 283 ORFs. The C. albicans secretome database is available at http://info.med.yale.edu/intmed/infdis/candida/
Collapse
Affiliation(s)
- Samuel A Lee
- Infectious Diseases Section, Department of Medicine, Yale University School of Medicine, New Haven, CT, USA.
| | | | | | | | | | | |
Collapse
|
25
|
Dumas B, Borel C, Herbert C, Maury J, Jacquet C, Balsse R, Esquerré-Tugayé MT. Molecular characterization of CLPT1, a SEC4-like Rab/GTPase of the phytopathogenic fungus Colletotrichum lindemuthianum which is regulated by the carbon source. Gene 2001; 272:219-25. [PMID: 11470528 DOI: 10.1016/s0378-1119(01)00536-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The gene CLPT1 (Colletotrichum lindemuthianum Protein Transport 1) encoding a Rab/GTPase was isolated from the filamentous fungus Colletotrichum lindemuthianum, the causal agent of bean anthracnose. At the amino acid level, CLPT1 shows between 54 and 80% identity to SEC4-like proteins, a class of molecules required for intracellular vesicular transport in yeasts. In particular, typical SEC4 domains involved in nucleotide binding and membrane attachment are present in the CLPT1 sequence. Functional identity of CLPT1 with SEC4 was confirmed by complementation of the Saccharomyces cerevisiae sec4-8 mutation. This is the first report of a gene involved in the control of intracellular vesicular trafficking in a phytopathogenic fungus. RNA blot analyses of CLPT1 expression were performed during in vitro growth of the fungus on synthetic media containing glucose or pectin, as single carbon source. The accumulation of CLPT1 mRNA was strongly increased on pectin, a plant cell wall polysaccharide that induces the production of extracellular pectinases, whereas the level of CLPT1 mRNA was below the detection threshold on glucose. These results suggest that CLPT1 is mainly involved in protein secretion and that the production of extracellular enzymes potentially involved in pathogenesis in filamentous fungi is sustained by induction of the genes involved in the secretory machinery.
Collapse
Affiliation(s)
- B Dumas
- UMR 5546 CNRS-Université Paul Sabatier, Pôle de Biotechnologie Végétale, 24 Chemin de Borde Rouge, BP17 Auzeville, 31326 Castanet-Tolosan, France.
| | | | | | | | | | | | | |
Collapse
|
26
|
Lee SA, Mao Y, Zhang Z, Wong B. Overexpression of a dominant-negative allele of YPT1 inhibits growth and aspartyl protease secretion in Candida albicans. MICROBIOLOGY (READING, ENGLAND) 2001; 147:1961-1970. [PMID: 11429473 DOI: 10.1099/00221287-147-7-1961] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
To investigate the pre-Golgi secretion pathway in the pathogenic yeast Candida albicans, we cloned the C. albicans homologue of the Saccharomyces cerevisiae protein secretion gene YPT1. The C. albicans YPT1 ORF contained a 624 bp intronless ORF encoding a deduced protein of 207 aa and 2.3 kDa. This deduced protein was 77% identical to S. cerevisiae Ypt1 protein (Ypt1p) and it contained GTP-binding domains that are conserved among all known ras-like GTPases. Multicopy plasmids containing C. albicans YPT1 complemented the temperature-sensitive S. cerevisiae ypt1 (A136D) mutation. One chromosomal YPT1 allele in C. albicans CAI4 was readily disrupted by homologous gene targeting, but attempts to disrupt the second allele yielded no viable null mutants. Since this suggested that C. albicans YPT1 may be essential, a mutant ypt1 allele was constructed encoding the amino acid substitution analogous to the N121I substitution in a known trans-dominant inhibitor of S. cerevisiae Ypt1p. Next, a GAL1-regulated plasmid was used to express the mutant ypt1(N121I) allele in C. albicans CAI4. Ten of 11 transformants tested grew normally in glucose and poorly in galactose, and plasmid curing restored growth to wild-type levels. When these transformants were incubated in galactose, secretion of aspartyl proteinase (Sap) was inhibited and membrane-bound secretory vesicles accumulated intracellularly. These results imply that C. albicans YPT1 is required for growth and protein secretion, and they confirm the feasibility of using inducible dominant-negative alleles to define the functions of essential genes in C. albicans.
Collapse
Affiliation(s)
- Samuel A Lee
- Infectious Diseases Section, VA Connecticut Healthcare System, 950 Campbell Ave, Bldg 8 (111-I), West Haven, CT 06516, USA2
- Infectious Diseases Section, Yale University School of Medicine, New Haven, CT 06520, USA1
| | - Yuxin Mao
- Infectious Diseases Section, Yale University School of Medicine, New Haven, CT 06520, USA1
| | - Zimei Zhang
- Infectious Diseases Section, Yale University School of Medicine, New Haven, CT 06520, USA1
| | - Brian Wong
- Infectious Diseases Section, VA Connecticut Healthcare System, 950 Campbell Ave, Bldg 8 (111-I), West Haven, CT 06516, USA2
- Infectious Diseases Section, Yale University School of Medicine, New Haven, CT 06520, USA1
| |
Collapse
|
27
|
Punt PJ, Seiboth B, Weenink XO, van Zeijl C, Lenders M, Konetschny C, Ram AF, Montijn R, Kubicek CP, van den Hondel CA. Identification and characterization of a family of secretion-related small GTPase-encoding genes from the filamentous fungus Aspergillus niger: a putative SEC4 homologue is not essential for growth. Mol Microbiol 2001; 41:513-25. [PMID: 11489135 DOI: 10.1046/j.1365-2958.2001.02541.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
DNA fragments containing genetic information for five secretion-related small GTPases of Aspergillus niger (srgA-E) were isolated and identified as members of different Rab/Ypt subfamilies. This isolation and the search for similar sequences in fungal genomic and EST databases showed that, in contrast to Saccharomyces cerevisiae, filamentous fungi also possess homologues of mammalian Rab2 GTPases. Multiple transcripts with unusually long 5' and 3' untranslated regions were found for all srg genes. Their level of expression was independent of the type of carbon source used for growth. Although the transcripts of srgA and srgB were abundant to the same extent throughout the cultivation, that of the other genes peaked during the early growth phase and then declined. Two genes, srgA and srgB, were characterized further. The protein encoded by srgA exhibited relatively low identity (58%) to its closest S. cerevisiae homologue SEC4, whereas the protein encoded by srgB showed 73% identity with S. cerevisiae YPT1. In contrast to other SEC4 homologues, srgA was unable to complement an S. cerevisiae sec4 mutant, and its disruption was not lethal in A. niger. SrgA mutants displayed a twofold increase in their hyphal diameter, unusual apical branching and strongly reduced protein secretion during growth on glucose.
Collapse
Affiliation(s)
- P J Punt
- Department of Applied Microbiology and Gene Technology, TNO Voeding, PO Box 360, 3700 AJ Zeist, The Netherlands.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Navarro-García F, Sánchez M, Nombela C, Pla J. Virulence genes in the pathogenic yeast Candida albicans. FEMS Microbiol Rev 2001; 25:245-68. [PMID: 11250036 DOI: 10.1111/j.1574-6976.2001.tb00577.x] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
In recent years, the incidence of fungal infections has been rising all over the world. Although the amount of research in the field of pathogenic fungi has also increased, there is still a need for the identification of reliable determinants of virulence. In this review, we focus on identified Candida albicans genes whose deletant strains have been tested in experimental virulence assays. We discuss the putative relationship of these genes to virulence and also outline the use of new different systems to examine the precise effect in virulence of different genes.
Collapse
Affiliation(s)
- F Navarro-García
- Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid, Spain
| | | | | | | |
Collapse
|
29
|
Huynh TT, Vad R, Kristensen T, Oyen TB. The genes of two G-proteins involved in protein transport in Pichia pastoris. Biochem Biophys Res Commun 2001; 280:454-9. [PMID: 11162538 DOI: 10.1006/bbrc.2000.4138] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Members of the Rab protein family play essential roles in vesicle fusion during protein secretion and represent highly conserved GTP binding proteins. The Saccharomyces cerevisiae Sec4p and Ypt1p, promoting vesicle fusion at the plasma membrane and in ER-Golgi transport, respectively, are among the best characterised yeast members. We have here cloned the Pichia pastoris SEC4 homologue using a S. cerevisiae SEC4 probe. In addition we isolated a crosshybridising clone encoding another Rab-/Ypt-like protein. The deduced full-length PpSec4p comprises 204 amino acid residues with an over all identity of 64% to the Sec4p from S. cerevisiae and 72% to the Candida albicans Sec4p. The YPT-like gene encodes a 216 amino acid residue protein showing highest similarity to the S. cerevisiae Ypt10p and Ypt53p. Both PpSec4p and the Ypt-like protein carry a -Cys-Cys C-terminus, indicating that these proteins are targets for geranyl-geranylation by a type II prenyltransferase.
Collapse
Affiliation(s)
- T T Huynh
- Department of Biochemistry, University of Oslo, Oslo, 0316, Norway
| | | | | | | |
Collapse
|
30
|
Weber Y, Santore UJ, Ernst JF, Swoboda RK. Divergence of eukaryotic secretory components: the Candida albicans homolog of the Saccharomyces cerevisiae ++Sec20 protein is N terminally truncated, and its levels determine antifungal drug resistance and growth. J Bacteriol 2001; 183:46-54. [PMID: 11114899 PMCID: PMC94848 DOI: 10.1128/jb.183.1.46-54.2001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sec20p is a component of the yeast Saccharomyces cerevisiae secretory pathway that does not have a close homolog in higher eukaryotic cells. To verify the function of Sec20p in other fungal species, we characterized the gene encoding a Sec20p homolog in the human fungal pathogen Candida albicans. The deduced protein has 27% identity with, but is missing about 100 N-terminal residues compared to S. cerevisiae Sec20p, which is part of the cytoplasmic tail interacting with the cytoplasmic protein Tip20p. Because a strain lacking both C. albicans SEC20 alleles could not be constructed, we placed SEC20 under transcriptional control of two regulatable promoters, MET3p and PCK1p. Repression of SEC20 expression in these strains prevented (MET3p-SEC20 allele) or retarded (PCK1p-SEC20 allele) growth and led to the appearance of extensive intracellular membranes, which frequently formed stacks. Reduced SEC20 expression in the PCK1p-SEC20 strain did not affect morphogenesis but led to a series of hypersensitivity phenotypes including supersensitivity to aminoglycoside antibiotics, to nystatin, to sodium dodecyl sulfate, and to cell wall inhibitors. These results demonstrate the occurrence and function of Sec20p in a fungal species other than S. cerevisiae, but the lack of the N-terminal domain and the apparent absence of a close TIP20 homolog in the C. albicans genome also indicate a considerable diversity in mechanisms of retrograde vesicle traffic in eukaryotes.
Collapse
Affiliation(s)
- Y Weber
- Institut für Mikrobiologie, Heinrich-Heine-Universität, D-40225 Düsseldorf, Germany
| | | | | | | |
Collapse
|
31
|
Backen AC, Broadbent ID, Fetherston RW, Rosamond JDC, Schnell NF, Stark MJR. Evaluation of theCaMAL2 promoter for regulated expression of genes inCandida albicans. Yeast 2000. [DOI: 10.1002/1097-0061(20000915)16:12%3c1121::aid-yea614%3e3.0.co;2-u] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
|
32
|
Backen AC, Broadbent ID, Fetherston RW, Rosamond JD, Schnell NF, Stark MJ. Evaluation of the CaMAL2 promoter for regulated expression of genes in Candida albicans. Yeast 2000; 16:1121-9. [PMID: 10953084 DOI: 10.1002/1097-0061(20000915)16:12<1121::aid-yea614>3.0.co;2-u] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
An expression vector (CIp10-MAL2p) for use in Candida albicans has been constructed in which a gene of interest can be placed under the control of the CaMAL2 maltase promoter and stably integrated at the CaRP10 locus. Using this vector to express the Candida URA3 gene from the CaMAL2 promoter, we have demonstrated tight regulation of CaURA3 expression by carbon source. Thus under conditions when the CaMAL2 promoter is not induced, expression of Candida URA3 was unable either to complement a C. albicans ura3 mutation or to confer sensitivity to 5-fluoroorotic acid, a compound which is highly toxic to URA3 strains. Since Candida albicans is an obligate diploid organism, analysis of gene function requires manipulation of both copies of any gene of interest. Our expression vector provides a strategy by which the remaining copy of a gene of interest can be placed under CaMAL2 promoter control in a strain where the first copy has been deleted, permitting analysis of gene function by manipulation of carbon source. CIp10-MAL2p should therefore provide a useful means for functional analysis of genes in C. albicans. We have used this strategy with C. albicans DPB2 to demonstrate that the gene is essential and that loss of function leads cells to adopt a hypha-like morphology as they cease proliferation.
Collapse
Affiliation(s)
- A C Backen
- University of Manchester, Stopford Building, Oxford Road, Manchester M13 9PT, UK
| | | | | | | | | | | |
Collapse
|