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Day AW, Kumamoto CA. Selection of ethanol tolerant strains of Candida albicans by repeated ethanol exposure results in strains with reduced susceptibility to fluconazole. PLoS One 2024; 19:e0298724. [PMID: 38377103 PMCID: PMC10878505 DOI: 10.1371/journal.pone.0298724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 01/23/2024] [Indexed: 02/22/2024] Open
Abstract
Candida albicans is a commensal yeast that has important impacts on host metabolism and immune function, and can establish life-threatening infections in immunocompromised individuals. Previously, C. albicans colonization has been shown to contribute to the progression and severity of alcoholic liver disease. However, relatively little is known about how C. albicans responds to changing environmental conditions in the GI tract of individuals with alcohol use disorder, namely repeated exposure to ethanol. In this study, we repeatedly exposed C. albicans to high concentrations (10% vol/vol) of ethanol-a concentration that can be observed in the upper GI tract of humans following consumption of alcohol. Following this repeated exposure protocol, ethanol small colony (Esc) variants of C. albicans isolated from these populations exhibited increased ethanol tolerance, altered transcriptional responses to ethanol, and cross-resistance/tolerance to the frontline antifungal fluconazole. These Esc strains exhibited chromosomal copy number variations and carried polymorphisms in genes previously associated with the acquisition of fluconazole resistance during human infection. This study identifies a selective pressure that can result in evolution of fluconazole tolerance and resistance without previous exposure to the drug.
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Affiliation(s)
- Andrew W. Day
- Graduate School of Biomedical Sciences, Tufts University, Boston, Massachusetts, United States of America
- Department of Molecular Biology and Microbiology, Tufts University, Boston, Massachusetts, United States of America
| | - Carol A. Kumamoto
- Department of Molecular Biology and Microbiology, Tufts University, Boston, Massachusetts, United States of America
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Day AW, Kumamoto CA. Selection of Ethanol Tolerant Strains of Candida albicans by Repeated Ethanol Exposure Results in Strains with Reduced Susceptibility to Fluconazole. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.13.557677. [PMID: 37745460 PMCID: PMC10515905 DOI: 10.1101/2023.09.13.557677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
Candida albicans is a commensal yeast that has important impacts on host metabolism and immune function, and can establish life-threatening infections in immunocompromised individuals. Previously, C. albicans colonization has been shown to contribute to the progression and severity of alcoholic liver disease. However, relatively little is known about how C. albicans responds to changing environmental conditions in the GI tract of individuals with alcohol use disorder, namely repeated exposure to ethanol. In this study, we repeatedly exposed C. albicans to high concentrations (10% vol/vol) of ethanol-a concentration that can be observed in the upper GI tract of humans following consumption of alcohol. Following this repeated exposure protocol, ethanol small colony (Esc) variants of C. albicans isolated from these populations exhibited increased ethanol tolerance, altered transcriptional responses to ethanol, and cross-resistance/tolerance to the frontline antifungal fluconazole. These Esc strains exhibited chromosomal copy number variations and carried polymorphisms in genes previously associated with the acquisition of fluconazole resistance during human infection. This study identifies a selective pressure that can result in evolution of fluconazole tolerance and resistance without previous exposure to the drug.
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Affiliation(s)
- Andrew W. Day
- Graduate School of Biomedical Sciences, Tufts University, Boston, Massachusetts, 02111, USA
- Department of Molecular Biology and Microbiology, Tufts University, Boston, Massachusetts, 02111, USA
| | - Carol A. Kumamoto
- Department of Molecular Biology and Microbiology, Tufts University, Boston, Massachusetts, 02111, USA
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Sullivan DJ, Berman J, Myers LC, Moran GP. Telomeric ORFS in Candida albicans: does mediator tail wag the yeast? PLoS Pathog 2015; 11:e1004614. [PMID: 25675446 PMCID: PMC4335505 DOI: 10.1371/journal.ppat.1004614] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Derek J. Sullivan
- Division of Oral Biosciences, Dublin Dental School and Hospital, University of Dublin, Trinity College Dublin, Dublin, Ireland
| | - Judith Berman
- Department of Molecular Microbiology & Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel
| | - Lawrence C. Myers
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - Gary P. Moran
- Division of Oral Biosciences, Dublin Dental School and Hospital, University of Dublin, Trinity College Dublin, Dublin, Ireland
- * E-mail:
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Anderson MZ, Gerstein AC, Wigen L, Baller JA, Berman J. Silencing is noisy: population and cell level noise in telomere-adjacent genes is dependent on telomere position and sir2. PLoS Genet 2014; 10:e1004436. [PMID: 25057900 PMCID: PMC4109849 DOI: 10.1371/journal.pgen.1004436] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 04/27/2014] [Indexed: 11/18/2022] Open
Abstract
Cell-to-cell gene expression noise is thought to be an important mechanism for generating phenotypic diversity. Furthermore, telomeric regions are major sites for gene amplification, which is thought to drive genetic diversity. Here we found that individual subtelomeric TLO genes exhibit increased variation in transcript and protein levels at both the cell-to-cell level as well as at the population-level. The cell-to-cell variation, termed Telomere-Adjacent Gene Expression Noise (TAGEN) was largely intrinsic noise and was dependent upon genome position: noise was reduced when a TLO gene was expressed at an ectopic internal locus and noise was elevated when a non-telomeric gene was expressed at a telomere-adjacent locus. This position-dependent TAGEN also was dependent on Sir2p, an NAD+-dependent histone deacetylase. Finally, we found that telomere silencing and TAGEN are tightly linked and regulated in cis: selection for either silencing or activation of a TLO-adjacent URA3 gene resulted in reduced noise at the neighboring TLO but not at other TLO genes. This provides experimental support to computational predictions that the ability to shift between silent and active chromatin states has a major effect on cell-to-cell noise. Furthermore, it demonstrates that these shifts affect the degree of expression variation at each telomere individually.
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Affiliation(s)
- Matthew Z. Anderson
- Department of Genetics, Cell Biology and Development, University of Minnesota – Twin Cities, Minneapolis, Minnesota, United States of America
| | - Aleeza C. Gerstein
- Department of Genetics, Cell Biology and Development, University of Minnesota – Twin Cities, Minneapolis, Minnesota, United States of America
- Department of Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel
| | - Lauren Wigen
- Department of Genetics, Cell Biology and Development, University of Minnesota – Twin Cities, Minneapolis, Minnesota, United States of America
| | - Joshua A. Baller
- Department of Genetics, Cell Biology and Development, University of Minnesota – Twin Cities, Minneapolis, Minnesota, United States of America
| | - Judith Berman
- Department of Genetics, Cell Biology and Development, University of Minnesota – Twin Cities, Minneapolis, Minnesota, United States of America
- Department of Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel
- * E-mail:
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The three clades of the telomere-associated TLO gene family of Candida albicans have different splicing, localization, and expression features. EUKARYOTIC CELL 2012; 11:1268-75. [PMID: 22923044 DOI: 10.1128/ec.00230-12] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Candida albicans grows within a wide range of host niches, and this adaptability enhances its success as a commensal and as a pathogen. The telomere-associated TLO gene family underwent a recent expansion from one or two copies in other CUG clade members to 14 expressed copies in C. albicans. This correlates with increased virulence and clinical prevalence relative to those of other Candida clade species. The 14 expressed TLO gene family members have a conserved Med2 domain at the N terminus, suggesting a role in general transcription. The C-terminal half is more divergent, distinguishing three clades: clade α and clade β have no introns and encode proteins that localize primarily to the nucleus; clade γ sometimes undergoes splicing, and the gene products localize within the mitochondria as well as the nuclei. Additionally, TLOα genes are generally expressed at much higher levels than are TLOγ genes. We propose that expansion of the TLO gene family and the predicted role of Tlo proteins in transcription regulation provide C. albicans with the ability to adapt rapidly to the broad range of different environmental niches within the human host.
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Nicholls S, Leach MD, Priest CL, Brown AJP. Role of the heat shock transcription factor, Hsf1, in a major fungal pathogen that is obligately associated with warm-blooded animals. Mol Microbiol 2009; 74:844-61. [PMID: 19818013 PMCID: PMC3675641 DOI: 10.1111/j.1365-2958.2009.06883.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
All organisms have evolved mechanisms that protect them against environmental stress. The major fungal pathogen of humans, Candida albicans, has evolved robust stress responses that protect it against human immune defences and promote its pathogenicity. However, C. albicans is unlikely to be exposed to heat shock as it is obligatorily associated with warm-blooded animals. Therefore, we examined the role of the heat shock transcription factor (Hsf1) in this pathogen. We show that C. albicans expresses an evolutionarily conserved Hsf1 (orf19.4775) that is phosphorylated in response to heat shock, induces transcription via the heat shock element (HSE), contributes to the global transcriptional response to heat shock, and is essential for viability. Why has Hsf1 been conserved in this obligate animal saprophyte? We reasoned that Hsf1 might contribute to medically relevant stress responses. However, this is not the case, as an Hsf1-specific HSE-lacZ reporter is not activated by oxidative, osmotic, weak acid or pH stress. Rather, Hsf1 is required for the expression of essential chaperones in the absence of heat shock (e.g. Hsp104, Hsp90, Hsp70). Furthermore, Hsf1 regulates the expression of HSE-containing genes in response to growth temperature in C. albicans. Therefore, the main role of Hsf1 in this pathogen might be the homeostatic modulation of chaperone levels in response to growth temperature, rather than the activation of acute responses to sudden thermal transitions.
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Affiliation(s)
- Susan Nicholls
- Aberdeen Fungal Group, School of Medical Sciences, University of Aberdeen, Institute of Medical Sciences, Aberdeen AB25 2ZD, UK
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Jackson AP, Gamble JA, Yeomans T, Moran GP, Saunders D, Harris D, Aslett M, Barrell JF, Butler G, Citiulo F, Coleman DC, de Groot PWJ, Goodwin TJ, Quail MA, McQuillan J, Munro CA, Pain A, Poulter RT, Rajandream MA, Renauld H, Spiering MJ, Tivey A, Gow NAR, Barrell B, Sullivan DJ, Berriman M. Comparative genomics of the fungal pathogens Candida dubliniensis and Candida albicans. Genome Res 2009; 19:2231-44. [PMID: 19745113 DOI: 10.1101/gr.097501.109] [Citation(s) in RCA: 169] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Candida dubliniensis is the closest known relative of Candida albicans, the most pathogenic yeast species in humans. However, despite both species sharing many phenotypic characteristics, including the ability to form true hyphae, C. dubliniensis is a significantly less virulent and less versatile pathogen. Therefore, to identify C. albicans-specific genes that may be responsible for an increased capacity to cause disease, we have sequenced the C. dubliniensis genome and compared it with the known C. albicans genome sequence. Although the two genome sequences are highly similar and synteny is conserved throughout, 168 species-specific genes are identified, including some encoding known hyphal-specific virulence factors, such as the aspartyl proteinases Sap4 and Sap5 and the proposed invasin Als3. Among the 115 pseudogenes confirmed in C. dubliniensis are orthologs of several filamentous growth regulator (FGR) genes that also have suspected roles in pathogenesis. However, the principal differences in genomic repertoire concern expansion of the TLO gene family of putative transcription factors and the IFA family of putative transmembrane proteins in C. albicans, which represent novel candidate virulence-associated factors. The results suggest that the recent evolutionary histories of C. albicans and C. dubliniensis are quite different. While gene families instrumental in pathogenesis have been elaborated in C. albicans, C. dubliniensis has lost genomic capacity and key pathogenic functions. This could explain why C. albicans is a more potent pathogen in humans than C. dubliniensis.
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Affiliation(s)
- Andrew P Jackson
- Pathogen Genomics Group, Wellcome Trust Sanger Institute, Cambridge, United Kingdom.
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Teutschbein J, Schartl M, Meierjohann S. Interaction of Xiphophorus and murine Fyn with focal adhesion kinase. Comp Biochem Physiol C Toxicol Pharmacol 2009; 149:168-74. [PMID: 18930841 DOI: 10.1016/j.cbpc.2008.09.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2008] [Revised: 09/08/2008] [Accepted: 09/09/2008] [Indexed: 11/17/2022]
Abstract
The Src family kinase/Focal Adhesion Kinase (FAK) complex is a signaling platform playing a crucial role in transformation downstream of oncogenic growth factor receptors. In the case of melanoma in Xiphophorus fish, the oncogenic EGF receptor orthologue Xiphophorus melanoma receptor kinase (Xmrk) effects continuous activation of the Src family kinase Fyn, but not of the other family members Src or Yes. Here, Fyn is strongly involved in promoting many tumorigenic events. Although Fyn is expressed in most mammalian tissues, there are only few reports of its involvement in the development of solid tumors. To find out whether the prominent role of Xiphophorus Fyn is based on an altered binding to its important binding partner FAK when compared to its mammalian Fyn counterparts, we performed yeast-two-hybrid analyses. We compared Xiphophorus and murine Fyn with respect to their binding to full-length and truncated FAK constructs. We found that interaction with FAK occurs similarly for Xiphophorus and mouse Fyn. Both phosphorylated FAK residue Y397 and FAK proline-rich domain are involved in Fyn binding. We also found interaction of FAK and Fyn in human melanoma cell lines. These data suggest a possible, yet unrecognized role of Fyn in the tumorigenesis of human melanoma, too.
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Affiliation(s)
- Janka Teutschbein
- Physiological Chemistry I, University of Würzburg, Biocenter, Am Hubland, D-97074 Würzburg, Germany
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Bourbon HM. Comparative genomics supports a deep evolutionary origin for the large, four-module transcriptional mediator complex. Nucleic Acids Res 2008; 36:3993-4008. [PMID: 18515835 PMCID: PMC2475620 DOI: 10.1093/nar/gkn349] [Citation(s) in RCA: 254] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The multisubunit Mediator (MED) complex bridges DNA-bound transcriptional regulators to the RNA polymerase II (PolII) initiation machinery. In yeast, the 25 MED subunits are distributed within three core subcomplexes and a separable kinase module composed of Med12, Med13 and the Cdk8-CycC pair thought to control the reversible interaction between MED and PolII by phosphorylating repeated heptapeptides within the Rpb1 carboxyl-terminal domain (CTD). Here, MED conservation has been investigated across the eukaryotic kingdom. Saccharomyces cerevisiae Med2, Med3/Pgd1 and Med5/Nut1 subunits are apparent homologs of metazoan Med29/Intersex, Med27/Crsp34 and Med24/Trap100, respectively, and these and other 30 identified human MED subunits have detectable counterparts in the amoeba Dictyostelium discoideum, indicating that none is specific to metazoans. Indeed, animal/fungal subunits are also conserved in plants, green and red algae, entamoebids, oomycetes, diatoms, apicomplexans, ciliates and the 'deep-branching' protists Trichomonas vaginalis and Giardia lamblia. Surprisingly, although lacking CTD heptads, T. vaginalis displays 44 MED subunit homologs, including several CycC, Med12 and Med13 paralogs. Such observations have allowed the identification of a conserved 17-subunit framework around which peripheral subunits may be assembled, and support a very ancient eukaryotic origin for a large, four-module MED. The implications of this comprehensive work for MED structure-function relationships are discussed.
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Affiliation(s)
- Henri-Marc Bourbon
- Centre de Biologie du Développement, UMR5547 CNRS/Toulouse III, IFR109, Université Paul Sabatier, 31062 Toulouse, France.
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Divergent functions of three Candida albicans zinc-cluster transcription factors (CTA4, ASG1 and CTF1) complementing pleiotropic drug resistance in Saccharomyces cerevisiae. Microbiology (Reading) 2008; 154:1491-1501. [DOI: 10.1099/mic.0.2007/016063-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Chiranand W, McLeod I, Zhou H, Lynn JJ, Vega LA, Myers H, Yates JR, Lorenz MC, Gustin MC. CTA4 transcription factor mediates induction of nitrosative stress response in Candida albicans. EUKARYOTIC CELL 2008; 7:268-78. [PMID: 18083829 PMCID: PMC2238162 DOI: 10.1128/ec.00240-07] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Accepted: 11/28/2007] [Indexed: 12/22/2022]
Abstract
This work has identified regulatory elements in the major fungal pathogen Candida albicans that enable response to nitrosative stress. Nitric oxide (NO) is generated by macrophages of the host immune system and commensal bacteria, and the ability to resist its toxicity is one adaptation that promotes survival of C. albicans inside the human body. Exposing C. albicans to NO induces upregulation of the flavohemoglobin Yhb1p. This protein confers protection by enzymatically converting NO to harmless nitrate, but it is unknown how C. albicans is able to detect NO in its environment and thus initiate this defense only as needed. We analyzed this problem by incrementally mutating the YHB1 regulatory region to identify a nitric oxide-responsive element (NORE) that is required for NO sensitivity. Five transcription factor candidates of the Zn(II)2-Cys6 family were then isolated from crude whole-cell extracts by using magnetic beads coated with this DNA element. Of the five, only deletion of the CTA4 gene prevented induction of YHB1 transcription during nitrosative stress and caused growth sensitivity to the NO donor dipropylenetriamine NONOate; Cta4p associates in vivo with NORE DNA from the YHB1 regulatory region. Deletion of CTA4 caused a small but significant decrease in virulence. A CTA4-dependent putative sulfite transporter encoded by SSU1 is also implicated in NO response, but C. albicans ssu1 mutants were not sensitive to NO, in contrast to findings in Saccharomyces cerevisiae. Cta4p is the first protein found to be necessary for initiating NO response in C. albicans.
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Affiliation(s)
- Wiriya Chiranand
- Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77251-1892, USA
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van het Hoog M, Rast TJ, Martchenko M, Grindle S, Dignard D, Hogues H, Cuomo C, Berriman M, Scherer S, Magee BB, Whiteway M, Chibana H, Nantel A, Magee PT. Assembly of the Candida albicans genome into sixteen supercontigs aligned on the eight chromosomes. Genome Biol 2007; 8:R52. [PMID: 17419877 PMCID: PMC1896002 DOI: 10.1186/gb-2007-8-4-r52] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2006] [Revised: 02/28/2007] [Accepted: 04/09/2007] [Indexed: 11/10/2022] Open
Abstract
For Assembly 20 of the Candida albicans genome, the sequence of each of the eight chromosomes was determined, revealing new insights into gene family creation and dispersion, subtelomere organization, and chromosome evolution. Background The 10.9× genomic sequence of Candida albicans, the most important human fungal pathogen, was published in 2004. Assembly 19 consisted of 412 supercontigs, of which 266 were a haploid set, since this fungus is diploid and contains an extensive degree of heterozygosity but lacks a complete sexual cycle. However, sequences of specific chromosomes were not determined. Results Supercontigs from Assembly 19 (183, representing 98.4% of the sequence) were assigned to individual chromosomes purified by pulse-field gel electrophoresis and hybridized to DNA microarrays. Nine Assembly 19 supercontigs were found to contain markers from two different chromosomes. Assembly 21 contains the sequence of each of the eight chromosomes and was determined using a synteny analysis with preliminary versions of the Candida dubliniensis genome assembly, bioinformatics, a sequence tagged site (STS) map of overlapping fosmid clones, and an optical map. The orientation and order of the contigs on each chromosome, repeat regions too large to be covered by a sequence run, such as the ribosomal DNA cluster and the major repeat sequence, and telomere placement were determined using the STS map. Sequence gaps were closed by PCR and sequencing of the products. The overall assembly was compared to an optical map; this identified some misassembled contigs and gave a size estimate for each chromosome. Conclusion Assembly 21 reveals an ancient chromosome fusion, a number of small internal duplications followed by inversions, and a subtelomeric arrangement, including a new gene family, the TLO genes. Correlations of position with relatedness of gene families imply a novel method of dispersion. The sequence of the individual chromosomes of C. albicans raises interesting biological questions about gene family creation and dispersion, subtelomere organization, and chromosome evolution.
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Affiliation(s)
- Marco van het Hoog
- Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec, H4P 2R2, Canada
| | | | - Mikhail Martchenko
- Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec, H4P 2R2, Canada
| | | | - Daniel Dignard
- Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec, H4P 2R2, Canada
| | - Hervé Hogues
- Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec, H4P 2R2, Canada
| | | | | | | | - BB Magee
- University of Minnesota, Minneapolis, MN, 55455, USA
| | - Malcolm Whiteway
- Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec, H4P 2R2, Canada
| | - Hiroji Chibana
- Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, Chiba, 260-8673, Japan
| | - André Nantel
- Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec, H4P 2R2, Canada
| | - PT Magee
- University of Minnesota, Minneapolis, MN, 55455, USA
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Mojzita D, Hohmann S. Pdc2 coordinates expression of the THI regulon in the yeast Saccharomyces cerevisiae. Mol Genet Genomics 2006; 276:147-61. [PMID: 16850348 DOI: 10.1007/s00438-006-0130-z] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2006] [Accepted: 04/15/2006] [Indexed: 10/24/2022]
Abstract
Coordination of gene expression in response to different metabolic signals is crucial for cellular homeostasis. In this work, we addressed the role of Pdc2 in the coordinated control of biosynthesis and demand of an essential metabolic cofactor, thiaminediphosphate (ThDP). The DNA binding protein Pdc2 was initially identified as a regulator of the genes PDC1 and PDC5, which encode isoforms of the glycolytic enzyme pyruvate decarboxylase (Pdc). The Pdc2 has also been implicated as a regulator of genes encoding enzymes in ThDP metabolism. The ThDP is the cofactor of Pdc. Using global and gene-specific expression analysis, we show that Pdc2 is required for the upregulation of all genes controlled by thiamine availability. The Pdc2 seems to act together with Thi2, a known transcriptional regulator of THI genes. The requirement for these two factors differs in a gene-specific manner. While the Thi2, in conjunction with Thi3, seems to control expression of THI genes with respect to thiamine availability, the Pdc2 may link the ThDP demand to carbon source availability. Interestingly, the enzymes Pdc1 and Pdc5 are enriched in the nucleus. Both are known to affect gene expression in an autoregulatory mechanism and expression of both is regulated by glucose and Pdc2, further pointing to a role of Pdc2 in coordinating different metabolic signals. Our analysis helps to further define the THI regulon and hence the spectrum of genes/proteins involved in the ThDP homeostasis. In particular, we identify novel proteins putatively involved in thiamine and/or ThDP transport across the plasma and the mitochondrial membrane. In conclusion, the THI regulon is the most interesting system to study principles of genes expression and metabolic coordination and deserves further attention.
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Affiliation(s)
- Dominik Mojzita
- Department of Cell and Molecular Biology/Microbiology, Göteborg University, PO Box 462, 405 30, Goteborg, Sweden
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Eck R, Nguyen M, Günther J, Künkel W, Zipfel PF. The phosphatidylinositol 3-kinase Vps34p of the human pathogenic yeast Candida albicans is a multifunctional protein that interacts with the putative vacuolar H+ -ATPase subunit Vma7p. Int J Med Microbiol 2005; 295:57-66. [PMID: 15861817 DOI: 10.1016/j.ijmm.2004.12.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The phosphatidylinositol 3-kinase Vps34p of Candida albicans participates in protein transport and in virulence. In order to characterize the functional link between these two activities we searched for proteins interacting with C. albicans Vps34p and demonstrate physical interaction of Vps34p with the subunit of the vacuolar H+ -ATPase Vma7p. The interaction initially observed in a yeast two-hybrid system was confirmed in vitro with recombinant proteins. Functional assays show that the Vps34p protein is necessary for vacuolar acidification and growth at alkaline pH. In addition, the vps34 null mutant of C. albicans shows defective autophagocytosis. The relevance of these functions for virulence of C. albicans is discussed.
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Affiliation(s)
- Raimund Eck
- Department of Infection Biology, Hans-Knöll-Institute for Natural Products Research, Beutenbergstrasse 11, D-07745 Jena, Germany.
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Sutak R, Tachezy J, Kulda J, Hrdý I. Pyruvate decarboxylase, the target for omeprazole in metronidazole-resistant and iron-restricted Tritrichomonas foetus. Antimicrob Agents Chemother 2004; 48:2185-9. [PMID: 15155220 PMCID: PMC415579 DOI: 10.1128/aac.48.6.2185-2189.2004] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The substituted benzimidazole omeprazole, used for the treatment of human peptic ulcer disease, inhibits the growth of the metronidazole-resistant bovine pathogen Tritrichomonas foetus in vitro (MIC at which the growth of parasite cultures is inhibited by 50%, 22 microg/ml [63 microM]). The antitrichomonad activity appears to be due to the inhibition of pyruvate decarboxylase (PDC), which is the key enzyme responsible for ethanol production and which is strongly upregulated in metronidazole-resistant trichomonads. PDC was purified to homogeneity from the cytosol of metronidazole-resistant strain. The tetrameric enzyme of 60-kDa subunits is inhibited by omeprazole (50% inhibitory concentration, 16 microg/ml). Metronidazole-susceptible T. foetus, which expresses very little PDC, is only slightly affected. Omeprazole has the same inhibitory effect on T. foetus cells grown under iron-limited conditions. Similarly to metronidazole-resistant cells, T. foetus cells grown under iron-limited conditions have nonfunctional hydrogenosomal metabolism and rely on cytosolic PDC-mediated ethanol fermentation.
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Affiliation(s)
- Róbert Sutak
- Department of Parasitology, Charles University, Vinicná 7, 128 44 Prague 2, Czech Republic
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Flores CL, Rodríguez C, Petit T, Gancedo C. Carbohydrate and energy-yielding metabolism in non-conventional yeasts. FEMS Microbiol Rev 2000; 24:507-29. [PMID: 10978549 DOI: 10.1111/j.1574-6976.2000.tb00553.x] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Sugars are excellent carbon sources for all yeasts. Since a vast amount of information is available on the components of the pathways of sugar utilization in Saccharomyces cerevisiae it has been tacitly assumed that other yeasts use sugars in the same way. However, although the pathways of sugar utilization follow the same theme in all yeasts, important biochemical and genetic variations on it exist. Basically, in most non-conventional yeasts, in contrast to S. cerevisiae, respiration in the presence of oxygen is prominent for the use of sugars. This review provides comparative information on the different steps of the fundamental pathways of sugar utilization in non-conventional yeasts: glycolysis, fermentation, tricarboxylic acid cycle, pentose phosphate pathway and respiration. We consider also gluconeogenesis and, briefly, catabolite repression. We have centered our attention in the genera Kluyveromyces, Candida, Pichia, Yarrowia and Schizosaccharomyces, although occasional reference to other genera is made. The review shows that basic knowledge is missing on many components of these pathways and also that studies on regulation of critical steps are scarce. Information on these points would be important to generate genetically engineered yeast strains for certain industrial uses.
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Affiliation(s)
- C L Flores
- Instituto de Investigaciones Biomédicas Alberto Sols C.S.I.C.-UAM, Unidad de Bioquímica y Genética de Levaduras, 28029, Madrid, Spain
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