Sequence of the<i>Candida albicans</i>gene encoding actin

Losberger, Christophe; Ernst, Joachim F.

doi:10.1093/nar/17.22.9488

Cited by 92 publications

(47 citation statements)

References 3 publications

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“…They include the gene which encodes actin (ACT) (34), the genes for ␤-tubulin (48), the calmodulin gene (44), and the peptide transport gene PTR2 (4). The 248-bp intron found in the C. albicans IMH3 gene has the hallmarks of S. cerevisiae introns as characterized by Kalogeropoulos (30).…”

Section: Discussionmentioning

confidence: 99%

Overexpression of a cloned IMP dehydrogenase gene of Candida albicans confers resistance to the specific inhibitor mycophenolic acid

1997

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An IMP dehydrogenase gene was isolated from Candida albicans on a ϳ2.9-kb XbaI genomic DNA fragment. The putative Candida IMP dehydrogenase gene (IMH3) encodes a protein of 521 amino acids with extensive sequence similarity to the IMP dehydrogenases of Saccharomyces cerevisiae and various other organisms. Like the S. cerevisiae IMH3 sequence characterized in the genome sequencing project, the open reading frame of the C. albicans IMH3 gene is interrupted by a small intron (248 bp) with typical exon-intron boundaries and a consensus S. cerevisiae branchpoint sequence. IMP dehydrogenase mRNAs are detected in both the yeast and hyphal forms of C. albicans as judged by Northern hybridization. Growth of wild-type (sensitive) C. albicans cells is inhibited at 1 g of mycophenolic acid (MPA), a specific inhibitor of IMP dehydrogenases, per ml, whereas transformants hosting a plasmid with the IMH3 gene are resistant to MPA levels of up to at least 40 g/ml. The resistance of cells to MPA is gene dosage dependent and suggests that IMH3 can be used as a dominant selection marker in C. albicans.IMP dehydrogenase (EC 1.1.1.205) is the key enzyme in the de novo biosynthesis of GMP, catalyzing the NAD-dependent oxidation of IMP to XMP. This conversion of IMP to XMP is the rate-limiting step in the biosynthetic pathway of guanine nucleotides, at least in mammals (26). While genes encoding IMP dehydrogenases have been isolated from archaea (11), protozoa (5, 54, 55), bacteria (2,3,16,31,36,47,49), plants (12), invertebrates (46), and mammals (10, 13, 39, 50), the only fungal sequences known are those encoding the putative IMP dehydrogenase genes sequenced in the Saccharomyces cerevisiae genome project (14,27,28). The polymorphic fungus Candida albicans is an opportunistic pathogen in immunocompromised individuals, causing oral and vaginal candidiasis as well as disseminated infections in neutropenic patients. Genetic manipulations of this diploid microorganism have been hampered by the apparent absence of a haploid phase and the dependence of marker systems on the spontaneous occurrence of auxotrophic mutants. Thus, the identification of the IMH3 gene in C. albicans suggested to us that mycophenolic acid (MPA), a specific inhibitor of IMP dehydrogenases, might be used to develop a dominant selectable marker system in Candida. In several other organisms, it has been shown that amplification of an IMP dehydrogenase gene can confer MPA resistance in a gene-dosage-dependent manner by overexpression of the enzyme (9,20,23,25,54). We report the cloning and sequencing of a DNA fragment of C. albicans with a coding region for a protein with high amino acid similarity and identity to known IMP dehydrogenases. Transformation of C.albicans by using a multicopy plasmid vector yielded transformants resistant to the specific IMP dehydrogenase inhibitor MPA. Culturing of transformant cells in the presence of MPA stabilized replicative plasmids, suggesting the feasibility of using IMH3 as a dominant selection marker for genetic studies in C. alb...

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Section: Discussionmentioning

confidence: 99%

Overexpression of a cloned IMP dehydrogenase gene of Candida albicans confers resistance to the specific inhibitor mycophenolic acid

1997

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“…The gene fragments were prepared by PCR amplification of a section of the coding region of the gene. The sections that were amplified and cloned were as follows (numbers represent positions in the GenBank sequences; GenBank accession numbers and references are given in parentheses): ERG11: position 164 to 1589 (X13296 [16]), MDR1: position 2885 to 3754 (X53823 [6]), CDR1: position 1210 to 2016 (X77589 [29]), and ACT1: position 1714 to 2515 (X16377, [18]). ACT1 is the gene encoding the actin gene and is used as a control in most of the experiments in this study.…”

Section: Methodsmentioning

confidence: 99%

Transcriptional Analyses of Antifungal Drug Resistance in Candida albicans

Lyons

White

2000

Antimicrob Agents Chemother

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Oral infections with the pathogenic yeast Candida albicans are one of the most frequent and earliest opportunistic infections in human immunodeficiency virus-infected patients. The widespread use of azole antifungal drugs has led to the development of drug-resistant isolates. Several molecular mechanisms that contribute to drug resistance have been identified, including increased mRNA levels for two types of efflux pump genes: the ATP binding cassette transporter CDRs (CDR1 and CDR2) and the major facilitator MDR1. Using Northern blot analyses, the expression patterns of these genes have been determined during logarithmic and stationary phases of cell growth and during growth in different carbon sources in a set of matched susceptible and fluconazole-resistant isolates that have been characterized previously. MDR1, CDR1, and CDR2 are expressed early during logarithmic growth, CDR4 is expressed late during logarithmic growth, and CDR1 is preferentially expressed in stationary-phase cells. There is a small decrease in expression of these genes when the cells are grown in carbon sources other than glucose. While increased mRNA levels of efflux pump genes are commonly associated with azole resistance, the causes of increased mRNA levels have not yet been resolved. Southern blot analysis demonstrates that the increased mRNA levels in these isolates are not the result of gene amplification. Nuclear run-on assays show that MDR1 and CDR mRNAs are transcriptionally overexpressed in the resistant isolate, suggesting that the antifungal drug resistance in this series is associated with the promoter and trans-acting factors of the CDR1, CDR2, and MDR1 genes.Candida albicans is a pathogenic yeast that causes oral, vaginal, and systemic infections (reviewed in reference 28). These infections are usually treated with antifungal drugs, including the polyene amphotericin B and the azoles, such as fluconazole. Azole-resistant strains of C. albicans are an increasing problem in human immunodeficiency virus-infected patients and other immunosuppressed individuals (37).

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“…Plasmid pED4 was digested with HindIII, XhoI, and XbaI resulting in three independent probes-namely, a 1.15-kb XhoI-HindIII fragment containing DAC1, a 1.33-kb HindIII-XbaI fragment containing NAG1, and a 1.42-kb XbaIHindIII fragment containing HXK1. The C. albicans ACT1 (22) probe used as control was derived from pCActin as a 1.5-kb SalI-EcoRI fragment. In case of the induction kinetics, the probes used were the 0.8-kb EcoRI fragment from the NAG1 cDNA clone (6), 0.925-kb BstNI-BstXI fragment from pED4 corresponding to DAC1, and a 444-bp NcoI-SalI fragment from pED4 corresponding to the HXK1.…”

Section: Methodsmentioning

confidence: 99%

The inducible N -acetylglucosamine catabolic pathway gene cluster in Candida albicans : Discrete N -acetylglucosamine-inducible factors interact at the promoter of NAG1

Kumar

Jamaluddin

Natarajan

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

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The catabolic pathway of N-acetylglucosamine (GlcNAc) in Candida albicans is an important facet of its pathogenicity. One of the pathway genes, encoding glucosamine-6-phosphate deaminase (NAG1) is transcriptionally regulated by GlcNAc. Sequence analysis of a 4-kb genomic clone containing NAG1 indicates that this gene is part of a cluster containing two other genes of the GlcNAc catabolic pathway, i.e., DAC1, GlcNAc-6-phosphate deacetylase, and HXK1, hexokinase. All three genes are temporally and coordinately induced by GlcNAc suggesting a common regulatory mechanism for these genes. The NAG1 promoter is up-regulated when induced by GlcNAc in C. albicans but not in Saccharomyces cerevisiae. In vivo analysis of the deletion constructs delineated the minimal promoter to ؊130 bp and mapped two regions at ؊200 and ؊400 bp upstream of ؉1 (ATG) responsible for GlcNAc induction. Gel mobility-shift assays and ''footprinting'' (DNase protection method) analyses revealed two regions, 5 -GGAGCAAAAAAATGT 3 (؊164 to ؊150, box A) and 5 -ACGGT-GAGTTG 3 (؊291 to ؊281, box B), that are recognized and bound by at least two inducible activator proteins directing the regulation of gene expression.

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Sequence of theCandida albicansgene encoding actin

Cited by 92 publications

References 3 publications

Overexpression of a cloned IMP dehydrogenase gene of Candida albicans confers resistance to the specific inhibitor mycophenolic acid

Overexpression of a cloned IMP dehydrogenase gene of Candida albicans confers resistance to the specific inhibitor mycophenolic acid

Transcriptional Analyses of Antifungal Drug Resistance in Candida albicans

The inducible N -acetylglucosamine catabolic pathway gene cluster in Candida albicans : Discrete N -acetylglucosamine-inducible factors interact at the promoter of NAG1

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