Isolation of the Candida albicans gene for orotidine-5′-phosphate decarboxylase by complementation of S. cerevisiae ura3 and E. coli pyrF mutations

Gillum, Amanda M.; Tsay, Emma Y. H.; Kirsch, Donald R.

doi:10.1007/bf00328721

Cited by 1,146 publications

(580 citation statements)

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“…Isolates were identified to the species level by the standard mycological methods of germ tube formation in serum, carbohydrate assimilation tests using the API 20C kit (bioMérieux, Inc., Hazelwood, MO) (29), and morphology on cornmeal agar. C. albicans SC5314 and C. parapsilosis ATCC 22019 were used as controls throughout (13). In addition, we analyzed well-characterized mutant C. albicans isolates created by the Ura-Blaster and SAT-flipper methods (1,2,14), along with their respective parental strains C. albicans SC5314 and CAI-12.…”

Section: Methodsmentioning

confidence: 99%

Paradoxical Effect of Caspofungin against Candida Bloodstream Isolates Is Mediated by Multiple Pathways but Eliminated in Human Serum

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et al. 2011

Antimicrob Agents Chemother

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Paradoxical growth of Candida in vitro at echinocandin concentrations exceeding the MIC is well described, but the clinical relevance is unknown. We assessed echinocandin paradoxical effects against Candida bloodstream isolates (BSI) in the presence or absence of human serum and investigated regulatory mechanisms. As determined by broth microdilution, a paradoxical effect was evident for 60% (18/30), 23% (7/30), and 13% (4/30) of Candida albicans BSI exposed to caspofungin, anidulafungin, and micafungin, respectively, at achievable human serum concentrations (<8 g/ml). A paradoxical effect was not evident among 34 C. glabrata BSI and was observed only for caspofungin against C. parapsilosis (4%, 1/23). As determined in time-kill studies, a caspofungin paradoxical effect was demonstrated by C. albicans (2/3), C. glabrata (1/3), and C. parapsilosis (1/3), including BSI that were determined to be negative by microdilution. In 50% human serum, a paradoxical effect was eliminated at caspofungin concentrations up to 64 g/ml for 100% (8/8) of the C. albicans BSI. A caspofungin paradoxical effect was also eliminated by chitin synthase inhibitor nikkomycin Z and at achievable concentrations of calcineurin pathway inhibitors, tacrolimus and cyclosporine. Moreover, these agents were synergistic with caspofungin against 100, 100, and 88% (7/8) of C. albicans, respectively, and exerted their own paradoxical effects. Finally, paradoxical growth was eliminated in C. albicans irs4-and inp51-null mutants, which lack phosphatidylinositol-(4,5)-bisphosphate 5 -phosphatase. Our findings suggest that the paradoxical effect is unlikely to be important in vivo but remains an important tool to study cell wall stress responses. We implicate the Irs4-Inp51 phosphatidylinositol-(4,5)-bisphosphate 5 -phosphatase as a novel regulator of paradoxical growth.The echinocandins have emerged as frontline agents for the treatment of invasive candidiasis (20). These agents exert concentration-dependent fungicidal effects through noncompetitive inhibition of ␤-1-3-glucan synthase, an enzyme that produces a major constituent of the fungal cell wall. Echinocandins are well tolerated in humans at up to three times the standard doses (4), a circumstance that has created interest in exploring the use of high-dose regimens to maximize clinical efficacy. Along these lines, concerns have been expressed about the possible therapeutic implications of an in vitro paradoxical effect, in which certain Candida isolates exhibit increased growth in the presence of echinocandin concentrations above the minimum inhibitory concentration (MIC). Although the paradoxical effect is typically apparent in vitro at concentrations that are achievable in human serum with conventional dosing strategies, the clinical relevance of the phenomenon in the treatment of patients with candidiasis is unproven.To date, paradoxical effects have been demonstrated against Candida albicans, C. parapsilosis, C. krusei, C. tropicalis, and C. dubliniensis isolates (3,5,10,16,23,25,28). Moreover...

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Section: Methodsmentioning

confidence: 99%

Paradoxical Effect of Caspofungin against Candida Bloodstream Isolates Is Mediated by Multiple Pathways but Eliminated in Human Serum

Shields

Press

et al. 2011

Antimicrob Agents Chemother

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“…On: Sun, 13 May 2018 00:01:43 template DNA purified from the wild-type strain SC5314 (Gillum et al, 1984). The amplified fragment was then digested with SalI and introduced into the equivalent site in pGEM-HIS1.…”

Section: Methodsmentioning

confidence: 99%

The CaCTR1 gene is required for high-affinity iron uptake and is transcriptionally controlled by a copper-sensing transactivator encoded by CaMAC1

Marvin

Cashmore

2004

Microbiology

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The ability of Candida albicans to acquire iron from the hostile environment of the host is known to be necessary for virulence and appears to be achieved using a similar system to that described for Saccharomyces cerevisiae. In S. cerevisiae, high-affinity iron uptake is dependent upon the acquisition of copper. The authors have previously identified a C. albicans gene (CaCTR1) that encodes a copper transporter. Deletion of this gene results in a mutant strain that grows predominantly as pseudohyphae and displays aberrant morphology in low-copper conditions. This paper demonstrates that invasive growth by C. albicans is induced by low-copper conditions and that this is augmented in a Cactr1-null strain. It also shows that deletion of CaCTR1 results in defective iron uptake. In S. cerevisiae, genes that facilitate high-affinity copper uptake are controlled by a copper-sensing transactivator, ScMac1p. The authors have now identified a C. albicans gene (CaMAC1) that encodes a copper-sensing transactivator. A Camac1-null mutant displays phenotypes similar to those of a Cactr1-null mutant and has no detectable CaCTR1 transcripts in low-copper conditions. It is proposed that high-affinity copper uptake by C. albicans is necessary for reductive iron uptake and is transcriptionally controlled by CaMac1p in a similar manner to that in S. cerevisiae.

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“…Wild-type C. albicans strain SC5134 was isolated from a systemic infection (Gillum et al, 1984). A C. albicans ctr1-null strain was generated from a derivative of this strain, BWP17 (ura3D : : limm434/ ura3D : : limm434; arg4 : : hisG/arg4 : : hisG; his1 : : hisG/his1 : : hisG), using PCR-directed mutagenesis (Wilson et al, 1999).…”

Section: Methodsmentioning

confidence: 99%

The Candida albicans CTR1 gene encodes a functional copper transporter

2003

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Copper and iron uptake in Saccharomyces cerevisiae are linked through a high-affinity ferric/cupric-reductive uptake system. Evidence suggests that a similar system operates in Candida albicans. The authors have identified a C. albicans gene that is able to rescue a S. cerevisiae ctr1/ctr3-null mutant defective in high-affinity copper uptake. The 756 bp ORF, designated CaCTR1, encodes a 251 amino acid protein with a molecular mass of 27·8 kDa. Comparisons between the deduced amino acid sequence of the C. albicans Ctr1p and S. cerevisiae Ctr1p indicated that they share 39·6 % similarity and 33·0 % identity over their entire length. Within the predicted protein product of CaCTR1 there are putative transmembrane regions and sequences that resemble copper-binding motifs. The promoter region of CaCTR1 contains four sequences with significant identity to S. cerevisiae copper response elements. CaCTR1 is transcriptionally regulated in S. cerevisiae in response to copper availability by the copper-sensing transactivator Mac1p. Transcription of CaCTR1 in C. albicans is also regulated in a copper-responsive manner. This raises the possibility that CaCTR1 may be regulated in C. albicans by a Mac1p-like transactivator. A C. albicans ctr1-null mutant displays phenotypes consistent with the lack of copper uptake including growth defects in low-copper and low-iron conditions, a respiratory deficiency and sensitivity to oxidative stress. Furthermore, changes in morphology were observed in the C. albicans ctr1-null mutant. It is proposed that CaCTR1 facilitates transport of copper into the cell.

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Isolation of the Candida albicans gene for orotidine-5′-phosphate decarboxylase by complementation of S. cerevisiae ura3 and E. coli pyrF mutations

Cited by 1,146 publications

References 20 publications

Paradoxical Effect of Caspofungin against Candida Bloodstream Isolates Is Mediated by Multiple Pathways but Eliminated in Human Serum

Paradoxical Effect of Caspofungin against Candida Bloodstream Isolates Is Mediated by Multiple Pathways but Eliminated in Human Serum

The CaCTR1 gene is required for high-affinity iron uptake and is transcriptionally controlled by a copper-sensing transactivator encoded by CaMAC1

The Candida albicans CTR1 gene encodes a functional copper transporter

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