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Calcáneo-Hernández G, Rojas-Espinosa E, Landeros-Jaime F, Cervantes-Chávez JA, Esquivel-Naranjo EU. An efficient transformation system for Trichoderma atroviride using the pyr4 gene as a selectable marker. Braz J Microbiol 2020; 51:1631-1643. [PMID: 32627116 DOI: 10.1007/s42770-020-00329-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 06/25/2020] [Indexed: 10/23/2022] Open
Abstract
The development of an efficient transformation system is essential to enrich the genetic understanding of Trichoderma atroviride. To acquire an additional homologous selectable marker, uracil auxotrophic mutants were generated. First, the pyr4 gene encoding OMP decarboxylase was replaced by the hph marker gene, encoding a hygromycin phosphotransferase. Then, uracil auxotrophs were employed to determine that 5 mM uracil restores their growth and conidia production, and 1 mg ml-1 is the lethal dose of 5-fluoroorotic acid in T. atroviride. Subsequently, uracil auxotrophic strains, free of a drug-selectable marker, were selected by 5-fluoroorotic acid resistance. Two different deletions in pyr4 were mapped in four auxotrophs, encoding a protein with frameshifts at the 310 and 335 amino acids in their COOH-terminal. Six auxotrophs did not have changes in the pyr4 ORF even though a specific cassette to delete the pyr4 was used, suggesting that 5-FOA could have mutagenic activity. The Ura-1 strain was selected as a genetic background to knock out the MAPKK Pbs2, MAPK Tmk3, and the blue light receptors Blr1/Blr2, using a short version of pyr4 as a homologous marker. The ∆tmk3 and ∆pbs2 mutants selected with pyr4 or hph marker were phenotypically identical, highly sensitive to different stressors, and affected in photoconidiation. The ∆blr1 and ∆blr2 mutants were not responsive to light, and complementation of uracil biosynthesis did not interfere in the expression of blu1, grg2, phr1, and env1 genes upregulated by blue light. Overall, uracil metabolism can be used as a tool for genetic manipulation in T. atroviride.
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Affiliation(s)
- Gabriela Calcáneo-Hernández
- Unit for Basic and Applied Microbiology, School of Natural Sciences, Autonomous University of Queretaro, 76140, Queretaro, Mexico
| | - Erick Rojas-Espinosa
- Unit for Basic and Applied Microbiology, School of Natural Sciences, Autonomous University of Queretaro, 76140, Queretaro, Mexico
| | - Fidel Landeros-Jaime
- Unit for Basic and Applied Microbiology, School of Natural Sciences, Autonomous University of Queretaro, 76140, Queretaro, Mexico
| | - José Antonio Cervantes-Chávez
- Unit for Basic and Applied Microbiology, School of Natural Sciences, Autonomous University of Queretaro, 76140, Queretaro, Mexico
| | - Edgardo Ulises Esquivel-Naranjo
- Unit for Basic and Applied Microbiology, School of Natural Sciences, Autonomous University of Queretaro, 76140, Queretaro, Mexico.
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Motaung T, Albertyn J, Pohl C, Köhler G. Candida albicans mutant construction and characterization of selected virulence determinants. J Microbiol Methods 2015; 115:153-65. [DOI: 10.1016/j.mimet.2015.06.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 06/09/2015] [Accepted: 06/10/2015] [Indexed: 11/22/2022]
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Löffler M, Carrey EA, Zameitat E. Orotic Acid, More Than Just an Intermediate of Pyrimidine de novo Synthesis. J Genet Genomics 2015; 42:207-19. [DOI: 10.1016/j.jgg.2015.04.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 04/04/2015] [Accepted: 04/09/2015] [Indexed: 01/21/2023]
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Delmas S, Llanos A, Parrou JL, Kokolski M, Pullan ST, Shunburne L, Archer DB. Development of an unmarked gene deletion system for the filamentous fungi Aspergillus niger and Talaromyces versatilis. Appl Environ Microbiol 2014; 80:3484-7. [PMID: 24682295 DOI: 10.1128/AEM.00625-14] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In this article, we present a method to delete genes in filamentous fungi that allows recycling of the selection marker and is efficient in a nonhomologous end-joining (NHEJ)-proficient strain. We exemplify the approach by deletion of the gene encoding the transcriptional regulator XlnR in the fungus Aspergillus niger. To show the efficiency and advantages of the method, we deleted 8 other genes and constructed a double mutant in this species. Moreover, we showed that the same principle also functions in a different genus of filamentous fungus (Talaromyces versatilis, basionym Penicillium funiculosum). This technique will increase the versatility of the toolboxes for genome manipulation of model and industrially relevant fungi.
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Abstract
In the United States, candidemia is one of the most common hospital-acquired infections and is estimated to cause 10,000 deaths per year. The species Candida albicans is responsible for the majority of these cases. As C. albicans is capable of developing resistance against the currently available drugs, understanding the molecular basis of drug resistance, finding new cellular targets, and further understanding the overall mechanism of C. albicans pathogenesis are important goals. To study this pathogen it is advantageous to manipulate its genome. Numerous strategies of C. albicans gene manipulation have been introduced. This review evaluates a majority of these strategies and should be a helpful guide for researchers to identify gene targeting strategies to suit their requirements.
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Affiliation(s)
- Dhanushki P Samaranayake
- Department of Biomedical Sciences, School of Public Health, State University of New York, Albany, NY 12208, USA.
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Qian W, Song H, Liu Y, Zhang C, Niu Z, Wang H, Qiu B. Improved gene disruption method and Cre-loxP mutant system for multiple gene disruptions in Hansenula polymorpha. J Microbiol Methods 2009; 79:253-9. [PMID: 19765620 DOI: 10.1016/j.mimet.2009.09.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2009] [Revised: 08/17/2009] [Accepted: 09/02/2009] [Indexed: 11/27/2022]
Abstract
In H. polymorpha, there is still a lack of a highly efficient gene disruption method. To help address this issue, we presented a simple and efficient method for both single and multiple gene disruptions in H. polymorpha. The knockout system combined a variation of sticky-end polymerase chain reaction method (SEP), split marker deletion method, co-transformation of single-stranded DNA and mutant Cre-loxP system. Using a slightly modified LiAc/SS-DNA/PEG procedure, the co-transformation double-stranded split marker constructs together with single-stranded split marker constructs resulted in at least 70% homologous recombination events when the homologous genomic DNA fragment had a size of approximately 500bp. Our evidence suggested that single-stranded DNA may be responsible for the increased gene disruption efficiency. We demonstrated the effectiveness of the method for gene disruption by constructing both single and double gene disruptions at the ALG3 and URA5 loci in the same genetic background. The method described here presents an improved strategy for gene disruption and a potential application for investigation of biological processes in other yeast strains.
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Affiliation(s)
- Weidong Qian
- Center for Agricultural Biotechnology, Institute of Microbiology, Chinese Academy of Sciences, No. 1 West Beichen Road, Beijing 100101, People's Republic of China
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Gomes AC, Miranda I, Silva RM, Moura GR, Thomas B, Akoulitchev A, Santos MAS. A genetic code alteration generates a proteome of high diversity in the human pathogen Candida albicans. Genome Biol 2008; 8:R206. [PMID: 17916231 PMCID: PMC2246281 DOI: 10.1186/gb-2007-8-10-r206] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Revised: 07/31/2007] [Accepted: 10/04/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Genetic code alterations have been reported in mitochondrial, prokaryotic, and eukaryotic cytoplasmic translation systems, but their evolution and how organisms cope and survive such dramatic genetic events are not understood. RESULTS Here we used an unusual decoding of leucine CUG codons as serine in the main human fungal pathogen Candida albicans to elucidate the global impact of genetic code alterations on the proteome. We show that C. albicans decodes CUG codons ambiguously and tolerates partial reversion of their identity from serine back to leucine on a genome-wide scale. CONCLUSION Such codon ambiguity expands the proteome of this human pathogen exponentially and is used to generate important phenotypic diversity. This study highlights novel features of C. albicans biology and unanticipated roles for codon ambiguity in the evolution of the genetic code.
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Affiliation(s)
- Ana C Gomes
- CESAM & Department of Biology, University of Aveiro, 3810-193 Aveiro, Portugal.
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Abstract
Candida albicans is a species of fungus that typically resides in the gastrointestinal tracts of humans and other warm-blooded animals. It is also the most common human fungal pathogen, causing a variety of skin and soft tissue infections in healthy people and more virulent invasive and disseminated diseases in patients with compromised immune systems. How this microorganism manages to persist in healthy hosts but also to cause a spectrum of disease states in the immunocompromised host are questions of significant biological interest as well as major clinical and economic importance. In this review, we describe recent developments in population genetics, the mating process, and gene disruption technology that are providing much needed experimental insights into the biology of C. albicans.
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Affiliation(s)
- Suzanne M Noble
- Department of Microbiology and Immunology, University of California-San Francisco, CA 94143-2200, USA.
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Legrand M, Forche A, Selmecki A, Chan C, Kirkpatrick DT, Berman J. Haplotype mapping of a diploid non-meiotic organism using existing and induced aneuploidies. PLoS Genet 2007; 4:e1. [PMID: 18179283 PMCID: PMC2174976 DOI: 10.1371/journal.pgen.0040001] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2007] [Accepted: 11/19/2007] [Indexed: 11/18/2022] Open
Abstract
Haplotype maps (HapMaps) reveal underlying sequence variation and facilitate the study of recombination and genetic diversity. In general, HapMaps are produced by analysis of Single-Nucleotide Polymorphism (SNP) segregation in large numbers of meiotic progeny. Candida albicans, the most common human fungal pathogen, is an obligate diploid that does not appear to undergo meiosis. Thus, standard methods for haplotype mapping cannot be used. We exploited naturally occurring aneuploid strains to determine the haplotypes of the eight chromosome pairs in the C. albicans laboratory strain SC5314 and in a clinical isolate. Comparison of the maps revealed that the clinical strain had undergone a significant amount of genome rearrangement, consisting primarily of crossover or gene conversion recombination events. SNP map haplotyping revealed that insertion and activation of the UAU1 cassette in essential and non-essential genes can result in whole chromosome aneuploidy. UAU1 is often used to construct homozygous deletions of targeted genes in C. albicans; the exact mechanism (trisomy followed by chromosome loss versus gene conversion) has not been determined. UAU1 insertion into the essential ORC1 gene resulted in a large proportion of trisomic strains, while gene conversion events predominated when UAU1 was inserted into the non-essential LRO1 gene. Therefore, induced aneuploidies can be used to generate HapMaps, which are essential for analyzing genome alterations and mitotic recombination events in this clonal organism. Candida albicans, a heterozygous diploid yeast, is the most prevalent fungal pathogen. It often acquires resistance to anti-fungal drugs via genome-altering recombination events. In many organisms, recombination events are analyzed using Haplotype Maps (HapMaps), which show the location of different alleles on each chromosomal homolog. Conventional HapMaps are constructed by following allelic markers as they segregate in meiotic progeny. Because C. albicans has not been shown to undergo meiosis, construction of a Candida HapMap has not been possible. We exploited the presence of whole chromosome aneuploidies in mitotic progeny of C. albicans to detect skewed ratios of different alleles, thereby determining the relationships between these alleles on each chromosomal homolog. This facilitated the construction of a HapMap for the most commonly used C. albicans laboratory strain. We then used this HapMap to identify all of the recombination events in a clinical isolate relative to the laboratory reference strain. Finally, we used this mapping approach to investigate the molecular mechanisms that affect the C. albicans genome when it is subjected to a common gene disruption technique. Our rapid HapMap construction method is generally applicable to any organism for which whole-chromosome aneuploidy events can be identified.
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Affiliation(s)
- Melanie Legrand
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Anja Forche
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Anna Selmecki
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Christine Chan
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - David T Kirkpatrick
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, United States of America
- * To whom correspondence should be addressed. E-mail: (DTK), (JB)
| | - Judith Berman
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, United States of America
- * To whom correspondence should be addressed. E-mail: (DTK), (JB)
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Nielsen ML, de Jongh WA, Meijer SL, Nielsen J, Mortensen UH. Transient marker system for iterative gene targeting of a prototrophic fungus. Appl Environ Microbiol 2007; 73:7240-5. [PMID: 17921280 DOI: 10.1128/AEM.01839-07] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Auxotrophic microorganisms are often used for genetic engineering, because their biosynthetic deficiency can be complemented by the transforming DNA and allows selection for transformants that have become prototrophic. However, when complementation is obtained by ectopic expression this may lead to unpredictable side effects on the phenotype and, consequently, misinterpretation of experimental data. There are various ways to overcome the problem of auxotrophy, but the most reliable is to restore the function of the defective biosynthetic gene at the native genomic locus. This can be done by either sexual crossing or further genetic engineering. For fungal species lacking a perfect state or situations in which gene targeting is generally cumbersome we have developed a concept that allows transient disruption of pyrG. When the gene is in the disrupted state, multiple rounds of gene targeting can be performed with the strain. Once the desired genome engineering is completed, pyrG function can be rapidly returned to wild type by a simple selection scheme.
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