Cloning, sequencing, expression and allelic sequence diversity of ERG3 (C-5 sterol desaturase gene) in Candida albicans

Infections with fluconazole-resistant Candida albicans isolate have rarely been described in clinical settings other than oropharyngeal candidiasis in patients with late-stage AIDS. We report on two patients with leukemia who developed fungemia caused by fluconazole-resistant C. albicans after receiving fluconazole prophylaxis (400 mg/day) and empiric amphotericin B therapy (0.5 mg/kg of body weight per day). The fluconazole MICs for the isolates were > or = 64 micrograms/ml, and the isolates were resistant to other azoles and had membrane sterol changes consistent with a mutation in the delta 5,6-sterol desaturase gene. The lack of ergosterol in the cytoplasmic membrane of the fluconazole-resistant strains also imparted resistance to amphotericin B. Both patients were successfully treated with high-dose amphotericin B (1 to 1.25 mg/kg/day) and flucytosine (150 mg/kg/day).

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Molecular and population genetic analysis of allelic sequence diversity at the human beta-globin locus.

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.91.5.1805 ◽

1994 ◽

Vol 91 (5) ◽

pp. 1805-1809 ◽

Cited By ~ 56

Author(s):

S. M. Fullerton ◽

R. M. Harding ◽

A. J. Boyce ◽

J. B. Clegg

Keyword(s):

Genetic Analysis ◽

Population Genetic ◽

Sequence Diversity ◽

Beta Globin ◽

Population Genetic Analysis ◽

Allelic Sequence

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Allelic sequence diversity at the human β-globin locus

Molecular Biology and Human Diversity ◽

10.1017/cbo9780511525643.017 ◽

1996 ◽

pp. 225-241

Author(s):

S. M. Fullerton

Keyword(s):

Sequence Diversity ◽

Allelic Sequence

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Construction and functional analysis of fatty acid desaturase gene disruptants in Candida albicans

Microbiology ◽

10.1099/mic.0.28751-0 ◽

2006 ◽

Vol 152 (5) ◽

pp. 1551-1558 ◽

Cited By ~ 21

Author(s):

Somay Yamagata Murayama ◽

Yumiko Negishi ◽

Takashi Umeyama ◽

Aki Kaneko ◽

Takahiro Oura ◽

...

Keyword(s):

Fatty Acids ◽

Candida Albicans ◽

Fatty Acid ◽

Palmitoleic Acid ◽

Culture Media ◽

Fatty Acid Desaturase ◽

Monounsaturated Fatty Acids ◽

Fatty Acid Desaturases ◽

Desaturase Gene ◽

Phenotypic Analysis

Polyunsaturated fatty acids (PUFAs), including linoleic acid (C18 : 2) and α-linolenic acid (C18 : 3), are major components of membranes. PUFAs are produced from monounsaturated fatty acids by several fatty acid desaturases (FADs) in many fungi, but Saccharomyces cerevisiae, Schizosaccharomyces pombe and humans do not have these enzymes. Although the fungal pathogen Candida albicans produces C18 : 2 and C18 : 3, the enzymes that synthesize them have not yet been investigated. In this report, two ORFs, CaFAD2 and CaFAD3, were identified based on their homology to other yeast FADs, and CaFAD2 and CaFAD3 gene disruptants were constructed. Cafad2Δ and Cafad3Δ lost their ability to produce C18 : 2 and C18 : 3, respectively. Furthermore, S. cerevisiae cells expressing CaFad2p converted palmitoleic acid (C16 : 1) and C18 : 1 to hexadecadienoic acid (C16 : 2) and C18 : 2, respectively, and CaFad3p-expressing cells converted C18 : 2 to C18 : 3. These results strongly supported that CaFAD2 encodes the Δ12 FAD and that CaFAD3 encodes the ω3 FAD. However, phenotypic analysis demonstrated that the presence of these PUFAs did not affect the virulence to mice, or morphogenesis in the culture media used to induce morphological change of C. albicans.

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Disruption of the sphingolipid Δ8-desaturase gene causes a delay in morphological changes in Candida albicans

Microbiology ◽

10.1099/mic.0.2008/018788-0 ◽

2008 ◽

Vol 154 (12) ◽

pp. 3795-3803 ◽

Cited By ~ 39

Author(s):

Takahiro Oura ◽

Susumu Kajiwara

Keyword(s):

Candida Albicans ◽

Morphological Changes ◽

Desaturase Gene

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Allelic variation in the contiguous loci encoding Candida albicans ALS5, ALS1 and ALS9

Microbiology ◽

10.1099/mic.0.26495-0 ◽

2003 ◽

Vol 149 (10) ◽

pp. 2947-2960 ◽

Cited By ~ 51

Author(s):

Xiaomin Zhao ◽

Claude Pujol ◽

David R. Soll ◽

Lois L. Hoyer

Keyword(s):

Candida Albicans ◽

Allelic Variation ◽

Sequence Divergence ◽

Repeated Sequences ◽

Pcr Analysis ◽

Sequencing Project ◽

Double Deletion ◽

Variable Block ◽

Allelic Sequence ◽

Genes Encoding

The ALS gene family of Candida albicans consists of eight genes (ALS1 to ALS7 and ALS9) that encode cell-wall glycoproteins involved in adhesion to host surfaces. Considerable allelic sequence variability has been documented for regions of ALS genes encoding repeated sequences. Although regions of ALS genes encoding non-repeated sequences tend to be more conserved, some sequence divergence has been noted, particularly for alleles of ALS5. Data from the C. albicans genome sequencing project provided the first indication that strain SC5314 encoded two divergent ALS9-like sequences and that three of the ALS genes (ALS5, ALS1 and ALS9) were contiguous on chromosome 6. Data from PCR analysis and construction of both single and double deletion mutants indicated that the divergent sequences were alleles of ALS9, and located downstream of ALS5 and ALS1. Sequences within the 5′ domain of ALS9-1 and ALS9-2 varied by 11 %. Within the 3′ domain of each allele, extra nucleotides were present in two regions of ALS9-2, designated Variable Block 1 (VB1) and Variable Block 2 (VB2). Analysis of strains from the five major C. albicans genetic clades showed that both ALS9 alleles are widespread among these strains, that the sequences of ALS9-1 and ALS9-2 are conserved among diverse strains and that recombinant ALS9 alleles have been generated during C. albicans evolution. Phylogenetic analysis showed that, although divergent in sequence, ALS9 alleles are more similar to each other than to any other ALS genes. The degree of sequence divergence for ALS9 greatly exceeds that observed previously for other ALS genes and may result in functional differences for the proteins encoded by the two alleles.

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