Limits...
Telomeric ORFs (TLOs) in Candida spp. Encode mediator subunits that regulate distinct virulence traits.

Haran J, Boyle H, Hokamp K, Yeomans T, Liu Z, Church M, Fleming AB, Anderson MZ, Berman J, Myers LC, Sullivan DJ, Moran GP - PLoS Genet. (2014)

Bottom Line: Complementation with TLO1 also had a greater effect on doubling times in galactose broth.The different abilities of TLO1 and TLO2 to restore wild-type functions was supported by transcript profiling studies that showed that only TLO1 restored expression of hypha-specific genes (UME6, SOD5) and galactose utilisation genes (GAL1 and GAL10), whereas TLO2 restored repression of starvation-induced gene transcription.Thus, Tlo/Med2 paralogs encoding Mediator subunits regulate different virulence properties in Candida spp. and their expansion may account for the increased adaptability of C. albicans relative to other Candida species.

View Article: PubMed Central - PubMed

Affiliation: Division of Oral Biosciences, Dublin Dental University Hospital, University of Dublin, Trinity College Dublin, Dublin, Ireland.

ABSTRACT
The TLO genes are a family of telomere-associated ORFs in the fungal pathogens Candida albicans and C. dubliniensis that encode a subunit of the Mediator complex with homology to Med2. The more virulent pathogen C. albicans has 15 copies of the gene whereas the less pathogenic species C. dubliniensis has only two (CdTLO1 and CdTLO2). In this study we used C. dubliniensis as a model to investigate the role of TLO genes in regulating virulence and also to determine whether TLO paralogs have evolved to regulate distinct functions. A C. dubliniensis tlo1Δ/tlo2Δ mutant is unable to form true hyphae, has longer doubling times in galactose broth, is more susceptible to oxidative stress and forms increased levels of biofilm. Transcript profiling of the tlo1Δ/tlo2Δ mutant revealed increased expression of starvation responses in rich medium and retarded expression of hypha-induced transcripts in serum. ChIP studies indicated that Tlo1 binds to many ORFs including genes that exhibit high and low expression levels under the conditions analyzed. The altered expression of these genes in the tlo1Δ/tlo2Δ mutant indicates roles for Tlo proteins in transcriptional activation and repression. Complementation of the tlo1Δ/tlo2Δ mutant with TLO1, but not TLO2, restored wild-type filamentous growth, whereas only TLO2 fully suppressed biofilm growth. Complementation with TLO1 also had a greater effect on doubling times in galactose broth. The different abilities of TLO1 and TLO2 to restore wild-type functions was supported by transcript profiling studies that showed that only TLO1 restored expression of hypha-specific genes (UME6, SOD5) and galactose utilisation genes (GAL1 and GAL10), whereas TLO2 restored repression of starvation-induced gene transcription. Thus, Tlo/Med2 paralogs encoding Mediator subunits regulate different virulence properties in Candida spp. and their expansion may account for the increased adaptability of C. albicans relative to other Candida species.

Show MeSH

Related in: MedlinePlus

Phenotypic analysis of C. dubliniensis tloΔ and med3Δ mutants.The rate of formation of true hyphae in water supplemented with 10% serum was measured in the tlo1Δ, tlo2Δ and tlo1Δ/tlo2Δ (tloΔΔ) mutants relative to Wü284 (A), in the TLO1 and TLO2 reintegrants (tloΔΔ+TLO1/2)(B) and in the med3Δ mutant (C). Measurements were taken over a period of 5 h by counting the number of cells producing unconstricted germ-tubes and expressing this value as a percentage of the whole population. (D) Cellular morphology of Wü284, the tlo1Δ/tlo2Δ (tloΔΔ) mutant and TLO1 and TLO2 reintegrated strains in 10% serum following staining with calcofluor white. (E) Oxidative stress susceptibility in tloΔ mutants. Susceptibility to oxidative stress was assessed by spotting 20 µl aliquots of 10-fold serially diluted suspensions (106 to 103 cells/ml) of the indicated strains on YEPD agar plates containing 7 mM H2O2 or 100 mM menadione. Plates were incubated for 48 h at 37°C.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4214616&req=5

pgen-1004658-g003: Phenotypic analysis of C. dubliniensis tloΔ and med3Δ mutants.The rate of formation of true hyphae in water supplemented with 10% serum was measured in the tlo1Δ, tlo2Δ and tlo1Δ/tlo2Δ (tloΔΔ) mutants relative to Wü284 (A), in the TLO1 and TLO2 reintegrants (tloΔΔ+TLO1/2)(B) and in the med3Δ mutant (C). Measurements were taken over a period of 5 h by counting the number of cells producing unconstricted germ-tubes and expressing this value as a percentage of the whole population. (D) Cellular morphology of Wü284, the tlo1Δ/tlo2Δ (tloΔΔ) mutant and TLO1 and TLO2 reintegrated strains in 10% serum following staining with calcofluor white. (E) Oxidative stress susceptibility in tloΔ mutants. Susceptibility to oxidative stress was assessed by spotting 20 µl aliquots of 10-fold serially diluted suspensions (106 to 103 cells/ml) of the indicated strains on YEPD agar plates containing 7 mM H2O2 or 100 mM menadione. Plates were incubated for 48 h at 37°C.

Mentions: Deletion of TLO2 did not reduce filamentous growth significantly (Figure 3A), while deletion of TLO1 resulted in reduced hyphal production (Figure 3A), as reported previously [14]. However, the double tlo1Δ/tlo2Δ mutant (tloΔΔ) had a more severe filamentation defect than the TLO1 deletion alone, suggesting that TLO2 partly compensates for the deletion of TLO1 in the single mutant (Figure 3A, 3D). The cellular morphology of the tlo1Δ/tlo2Δ mutant in 10% serum was characteristically pseudohyphal (Figure 3D).


Telomeric ORFs (TLOs) in Candida spp. Encode mediator subunits that regulate distinct virulence traits.

Haran J, Boyle H, Hokamp K, Yeomans T, Liu Z, Church M, Fleming AB, Anderson MZ, Berman J, Myers LC, Sullivan DJ, Moran GP - PLoS Genet. (2014)

Phenotypic analysis of C. dubliniensis tloΔ and med3Δ mutants.The rate of formation of true hyphae in water supplemented with 10% serum was measured in the tlo1Δ, tlo2Δ and tlo1Δ/tlo2Δ (tloΔΔ) mutants relative to Wü284 (A), in the TLO1 and TLO2 reintegrants (tloΔΔ+TLO1/2)(B) and in the med3Δ mutant (C). Measurements were taken over a period of 5 h by counting the number of cells producing unconstricted germ-tubes and expressing this value as a percentage of the whole population. (D) Cellular morphology of Wü284, the tlo1Δ/tlo2Δ (tloΔΔ) mutant and TLO1 and TLO2 reintegrated strains in 10% serum following staining with calcofluor white. (E) Oxidative stress susceptibility in tloΔ mutants. Susceptibility to oxidative stress was assessed by spotting 20 µl aliquots of 10-fold serially diluted suspensions (106 to 103 cells/ml) of the indicated strains on YEPD agar plates containing 7 mM H2O2 or 100 mM menadione. Plates were incubated for 48 h at 37°C.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4214616&req=5

pgen-1004658-g003: Phenotypic analysis of C. dubliniensis tloΔ and med3Δ mutants.The rate of formation of true hyphae in water supplemented with 10% serum was measured in the tlo1Δ, tlo2Δ and tlo1Δ/tlo2Δ (tloΔΔ) mutants relative to Wü284 (A), in the TLO1 and TLO2 reintegrants (tloΔΔ+TLO1/2)(B) and in the med3Δ mutant (C). Measurements were taken over a period of 5 h by counting the number of cells producing unconstricted germ-tubes and expressing this value as a percentage of the whole population. (D) Cellular morphology of Wü284, the tlo1Δ/tlo2Δ (tloΔΔ) mutant and TLO1 and TLO2 reintegrated strains in 10% serum following staining with calcofluor white. (E) Oxidative stress susceptibility in tloΔ mutants. Susceptibility to oxidative stress was assessed by spotting 20 µl aliquots of 10-fold serially diluted suspensions (106 to 103 cells/ml) of the indicated strains on YEPD agar plates containing 7 mM H2O2 or 100 mM menadione. Plates were incubated for 48 h at 37°C.
Mentions: Deletion of TLO2 did not reduce filamentous growth significantly (Figure 3A), while deletion of TLO1 resulted in reduced hyphal production (Figure 3A), as reported previously [14]. However, the double tlo1Δ/tlo2Δ mutant (tloΔΔ) had a more severe filamentation defect than the TLO1 deletion alone, suggesting that TLO2 partly compensates for the deletion of TLO1 in the single mutant (Figure 3A, 3D). The cellular morphology of the tlo1Δ/tlo2Δ mutant in 10% serum was characteristically pseudohyphal (Figure 3D).

Bottom Line: Complementation with TLO1 also had a greater effect on doubling times in galactose broth.The different abilities of TLO1 and TLO2 to restore wild-type functions was supported by transcript profiling studies that showed that only TLO1 restored expression of hypha-specific genes (UME6, SOD5) and galactose utilisation genes (GAL1 and GAL10), whereas TLO2 restored repression of starvation-induced gene transcription.Thus, Tlo/Med2 paralogs encoding Mediator subunits regulate different virulence properties in Candida spp. and their expansion may account for the increased adaptability of C. albicans relative to other Candida species.

View Article: PubMed Central - PubMed

Affiliation: Division of Oral Biosciences, Dublin Dental University Hospital, University of Dublin, Trinity College Dublin, Dublin, Ireland.

ABSTRACT
The TLO genes are a family of telomere-associated ORFs in the fungal pathogens Candida albicans and C. dubliniensis that encode a subunit of the Mediator complex with homology to Med2. The more virulent pathogen C. albicans has 15 copies of the gene whereas the less pathogenic species C. dubliniensis has only two (CdTLO1 and CdTLO2). In this study we used C. dubliniensis as a model to investigate the role of TLO genes in regulating virulence and also to determine whether TLO paralogs have evolved to regulate distinct functions. A C. dubliniensis tlo1Δ/tlo2Δ mutant is unable to form true hyphae, has longer doubling times in galactose broth, is more susceptible to oxidative stress and forms increased levels of biofilm. Transcript profiling of the tlo1Δ/tlo2Δ mutant revealed increased expression of starvation responses in rich medium and retarded expression of hypha-induced transcripts in serum. ChIP studies indicated that Tlo1 binds to many ORFs including genes that exhibit high and low expression levels under the conditions analyzed. The altered expression of these genes in the tlo1Δ/tlo2Δ mutant indicates roles for Tlo proteins in transcriptional activation and repression. Complementation of the tlo1Δ/tlo2Δ mutant with TLO1, but not TLO2, restored wild-type filamentous growth, whereas only TLO2 fully suppressed biofilm growth. Complementation with TLO1 also had a greater effect on doubling times in galactose broth. The different abilities of TLO1 and TLO2 to restore wild-type functions was supported by transcript profiling studies that showed that only TLO1 restored expression of hypha-specific genes (UME6, SOD5) and galactose utilisation genes (GAL1 and GAL10), whereas TLO2 restored repression of starvation-induced gene transcription. Thus, Tlo/Med2 paralogs encoding Mediator subunits regulate different virulence properties in Candida spp. and their expansion may account for the increased adaptability of C. albicans relative to other Candida species.

Show MeSH
Related in: MedlinePlus