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The Candida albicans Histone Acetyltransferase Hat1 Regulates Stress Resistance and Virulence via Distinct Chromatin Assembly Pathways.

Tscherner M, Zwolanek F, Je S, Sedlazeck FJ, Petryshyn A, Frohner IE, Mavrianos J, Chauhan N, von Haeseler A, Kuchler K - PLoS Pathog. (2015)

Bottom Line: Hydrogen peroxide resistance in cells lacking Hat1 results from higher induction rates of oxidative stress gene expression, accompanied by reduced histone density as well as subsequent increased RNA polymerase recruitment.Remarkably, the oxidative stress phenotype of hat1Δ/Δ cells is a species-specific trait only found in C. albicans and members of the CTG clade.The reduced azole susceptibility appears to be conserved in a wider range of fungi.

View Article: PubMed Central - PubMed

Affiliation: Department for Medical Biochemistry, Medical University of Vienna, Max F. Perutz Laboratories, Campus Vienna Biocenter, Vienna, Austria.

ABSTRACT
Human fungal pathogens like Candida albicans respond to host immune surveillance by rapidly adapting their transcriptional programs. Chromatin assembly factors are involved in the regulation of stress genes by modulating the histone density at these loci. Here, we report a novel role for the chromatin assembly-associated histone acetyltransferase complex NuB4 in regulating oxidative stress resistance, antifungal drug tolerance and virulence in C. albicans. Strikingly, depletion of the NuB4 catalytic subunit, the histone acetyltransferase Hat1, markedly increases resistance to oxidative stress and tolerance to azole antifungals. Hydrogen peroxide resistance in cells lacking Hat1 results from higher induction rates of oxidative stress gene expression, accompanied by reduced histone density as well as subsequent increased RNA polymerase recruitment. Furthermore, hat1Δ/Δ cells, despite showing growth defects in vitro, display reduced susceptibility to reactive oxygen-mediated killing by innate immune cells. Thus, clearance from infected mice is delayed although cells lacking Hat1 are severely compromised in killing the host. Interestingly, increased oxidative stress resistance and azole tolerance are phenocopied by the loss of histone chaperone complexes CAF-1 and HIR, respectively, suggesting a central role for NuB4 in the delivery of histones destined for chromatin assembly via distinct pathways. Remarkably, the oxidative stress phenotype of hat1Δ/Δ cells is a species-specific trait only found in C. albicans and members of the CTG clade. The reduced azole susceptibility appears to be conserved in a wider range of fungi. Thus, our work demonstrates how highly conserved chromatin assembly pathways can acquire new functions in pathogenic fungi during coevolution with the host.

No MeSH data available.


Resistance phenotypes caused by loss of Hat1 are specific for C. albicans.(A) Deletion of HAT1 in S. cerevisiae (a), C. glabrata (b) and S. pombe (c) has no effect on H2O2 resistance. Exponentially growing cells were treated with 5 mM (a), 50 mM (b) or 20 mM (c) H2O2 for 2 hours. Cells were plated and colonies counted after 3 days of incubation on YPD plates at 30°C to determine viability. Data are shown as mean + SD from three independent experiments. (B) Lack of Hat1 in S. cerevisiae (a) and C. glabrata (b) does not increase azole tolerance. Deletion of Hat1 in S. pombe reduces susceptibility to voriconazole (c). Logarithmically growing cells were diluted into medium containing 150 ng/ml (a), 1000 ng/ml (b) or 800 ng/ml (c) voriconazole and incubated at 30°C for 24 hours. OD600 was determined and growth inhibition relative to untreated samples was calculated. Data are shown as mean + SD from three independent experiments. (C) C. parapsilosis (a) and C. tropicalis (b) hat1Δ/Δ cells show increased resistance to H2O2. Experiment was performed as described in (A). H2O2 concentrations were 50 mM (a) and 20 mM (b). (D) Loss of Hat1 in C. parapsilosis (a) and C. tropicalis (b) reduces susceptibility to voriconazole. Experiment was performed as described in (B). For C. parapsilosis cells were incubated for 41 hours prior to OD600 measurement. Voriconazole concentrations were 50 ng/ml (a) and 200 ng/ml (b). (A-D) *P<0.05, **P<0.01 and ***P<0.001 relative to the corresponding wild-type (Student's t-test).
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ppat.1005218.g003: Resistance phenotypes caused by loss of Hat1 are specific for C. albicans.(A) Deletion of HAT1 in S. cerevisiae (a), C. glabrata (b) and S. pombe (c) has no effect on H2O2 resistance. Exponentially growing cells were treated with 5 mM (a), 50 mM (b) or 20 mM (c) H2O2 for 2 hours. Cells were plated and colonies counted after 3 days of incubation on YPD plates at 30°C to determine viability. Data are shown as mean + SD from three independent experiments. (B) Lack of Hat1 in S. cerevisiae (a) and C. glabrata (b) does not increase azole tolerance. Deletion of Hat1 in S. pombe reduces susceptibility to voriconazole (c). Logarithmically growing cells were diluted into medium containing 150 ng/ml (a), 1000 ng/ml (b) or 800 ng/ml (c) voriconazole and incubated at 30°C for 24 hours. OD600 was determined and growth inhibition relative to untreated samples was calculated. Data are shown as mean + SD from three independent experiments. (C) C. parapsilosis (a) and C. tropicalis (b) hat1Δ/Δ cells show increased resistance to H2O2. Experiment was performed as described in (A). H2O2 concentrations were 50 mM (a) and 20 mM (b). (D) Loss of Hat1 in C. parapsilosis (a) and C. tropicalis (b) reduces susceptibility to voriconazole. Experiment was performed as described in (B). For C. parapsilosis cells were incubated for 41 hours prior to OD600 measurement. Voriconazole concentrations were 50 ng/ml (a) and 200 ng/ml (b). (A-D) *P<0.05, **P<0.01 and ***P<0.001 relative to the corresponding wild-type (Student's t-test).

Mentions: Next, we wanted to determine if the role of Hat1 in the regulation of oxidative stress resistance and azole tolerance is conserved in other fungal species. Therefore, we analyzed the effect of HAT1 deletion on H2O2 and voriconazole susceptibility in the distantly related fungi Saccharomyces cerevisiae, Candida glabrata and Schizosaccharomyces pombe. However, loss of Hat1 did not lead to increased resistance to H2O2 in any of these species (Fig 3A). Furthermore, lack of Hat1 failed to lower voriconazole sensitivity in S. cerevisiae and C. glabrata (Fig 3B), but increased azole tolerance in S. pombe (Fig 3Bc).


The Candida albicans Histone Acetyltransferase Hat1 Regulates Stress Resistance and Virulence via Distinct Chromatin Assembly Pathways.

Tscherner M, Zwolanek F, Je S, Sedlazeck FJ, Petryshyn A, Frohner IE, Mavrianos J, Chauhan N, von Haeseler A, Kuchler K - PLoS Pathog. (2015)

Resistance phenotypes caused by loss of Hat1 are specific for C. albicans.(A) Deletion of HAT1 in S. cerevisiae (a), C. glabrata (b) and S. pombe (c) has no effect on H2O2 resistance. Exponentially growing cells were treated with 5 mM (a), 50 mM (b) or 20 mM (c) H2O2 for 2 hours. Cells were plated and colonies counted after 3 days of incubation on YPD plates at 30°C to determine viability. Data are shown as mean + SD from three independent experiments. (B) Lack of Hat1 in S. cerevisiae (a) and C. glabrata (b) does not increase azole tolerance. Deletion of Hat1 in S. pombe reduces susceptibility to voriconazole (c). Logarithmically growing cells were diluted into medium containing 150 ng/ml (a), 1000 ng/ml (b) or 800 ng/ml (c) voriconazole and incubated at 30°C for 24 hours. OD600 was determined and growth inhibition relative to untreated samples was calculated. Data are shown as mean + SD from three independent experiments. (C) C. parapsilosis (a) and C. tropicalis (b) hat1Δ/Δ cells show increased resistance to H2O2. Experiment was performed as described in (A). H2O2 concentrations were 50 mM (a) and 20 mM (b). (D) Loss of Hat1 in C. parapsilosis (a) and C. tropicalis (b) reduces susceptibility to voriconazole. Experiment was performed as described in (B). For C. parapsilosis cells were incubated for 41 hours prior to OD600 measurement. Voriconazole concentrations were 50 ng/ml (a) and 200 ng/ml (b). (A-D) *P<0.05, **P<0.01 and ***P<0.001 relative to the corresponding wild-type (Student's t-test).
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Related In: Results  -  Collection

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ppat.1005218.g003: Resistance phenotypes caused by loss of Hat1 are specific for C. albicans.(A) Deletion of HAT1 in S. cerevisiae (a), C. glabrata (b) and S. pombe (c) has no effect on H2O2 resistance. Exponentially growing cells were treated with 5 mM (a), 50 mM (b) or 20 mM (c) H2O2 for 2 hours. Cells were plated and colonies counted after 3 days of incubation on YPD plates at 30°C to determine viability. Data are shown as mean + SD from three independent experiments. (B) Lack of Hat1 in S. cerevisiae (a) and C. glabrata (b) does not increase azole tolerance. Deletion of Hat1 in S. pombe reduces susceptibility to voriconazole (c). Logarithmically growing cells were diluted into medium containing 150 ng/ml (a), 1000 ng/ml (b) or 800 ng/ml (c) voriconazole and incubated at 30°C for 24 hours. OD600 was determined and growth inhibition relative to untreated samples was calculated. Data are shown as mean + SD from three independent experiments. (C) C. parapsilosis (a) and C. tropicalis (b) hat1Δ/Δ cells show increased resistance to H2O2. Experiment was performed as described in (A). H2O2 concentrations were 50 mM (a) and 20 mM (b). (D) Loss of Hat1 in C. parapsilosis (a) and C. tropicalis (b) reduces susceptibility to voriconazole. Experiment was performed as described in (B). For C. parapsilosis cells were incubated for 41 hours prior to OD600 measurement. Voriconazole concentrations were 50 ng/ml (a) and 200 ng/ml (b). (A-D) *P<0.05, **P<0.01 and ***P<0.001 relative to the corresponding wild-type (Student's t-test).
Mentions: Next, we wanted to determine if the role of Hat1 in the regulation of oxidative stress resistance and azole tolerance is conserved in other fungal species. Therefore, we analyzed the effect of HAT1 deletion on H2O2 and voriconazole susceptibility in the distantly related fungi Saccharomyces cerevisiae, Candida glabrata and Schizosaccharomyces pombe. However, loss of Hat1 did not lead to increased resistance to H2O2 in any of these species (Fig 3A). Furthermore, lack of Hat1 failed to lower voriconazole sensitivity in S. cerevisiae and C. glabrata (Fig 3B), but increased azole tolerance in S. pombe (Fig 3Bc).

Bottom Line: Hydrogen peroxide resistance in cells lacking Hat1 results from higher induction rates of oxidative stress gene expression, accompanied by reduced histone density as well as subsequent increased RNA polymerase recruitment.Remarkably, the oxidative stress phenotype of hat1Δ/Δ cells is a species-specific trait only found in C. albicans and members of the CTG clade.The reduced azole susceptibility appears to be conserved in a wider range of fungi.

View Article: PubMed Central - PubMed

Affiliation: Department for Medical Biochemistry, Medical University of Vienna, Max F. Perutz Laboratories, Campus Vienna Biocenter, Vienna, Austria.

ABSTRACT
Human fungal pathogens like Candida albicans respond to host immune surveillance by rapidly adapting their transcriptional programs. Chromatin assembly factors are involved in the regulation of stress genes by modulating the histone density at these loci. Here, we report a novel role for the chromatin assembly-associated histone acetyltransferase complex NuB4 in regulating oxidative stress resistance, antifungal drug tolerance and virulence in C. albicans. Strikingly, depletion of the NuB4 catalytic subunit, the histone acetyltransferase Hat1, markedly increases resistance to oxidative stress and tolerance to azole antifungals. Hydrogen peroxide resistance in cells lacking Hat1 results from higher induction rates of oxidative stress gene expression, accompanied by reduced histone density as well as subsequent increased RNA polymerase recruitment. Furthermore, hat1Δ/Δ cells, despite showing growth defects in vitro, display reduced susceptibility to reactive oxygen-mediated killing by innate immune cells. Thus, clearance from infected mice is delayed although cells lacking Hat1 are severely compromised in killing the host. Interestingly, increased oxidative stress resistance and azole tolerance are phenocopied by the loss of histone chaperone complexes CAF-1 and HIR, respectively, suggesting a central role for NuB4 in the delivery of histones destined for chromatin assembly via distinct pathways. Remarkably, the oxidative stress phenotype of hat1Δ/Δ cells is a species-specific trait only found in C. albicans and members of the CTG clade. The reduced azole susceptibility appears to be conserved in a wider range of fungi. Thus, our work demonstrates how highly conserved chromatin assembly pathways can acquire new functions in pathogenic fungi during coevolution with the host.

No MeSH data available.