Dataset Information

Core oxidative stress response in Aspergillus nidulans.

ABSTRACT: The b-Zip transcription factor AtfA plays a key role in regulating stress responses in the filamentous fungus Aspergillus nidulans. To identify the core regulons of AtfA, we examined genome-wide expression changes caused by various stresses in the presence/absence of AtfA using A. nidulans microarrays. We also intended to address the intriguing question regarding the existence of core environmental stress response in this important model eukaryote.Examination of the genome wide expression changes caused by five different oxidative stress conditions in wild type and the atfA null mutant has identified a significant number of stereotypically regulated genes (Core Oxidative Stress Response genes). The deletion of atfA increased the oxidative stress sensitivity of A. nidulans and affected mRNA accumulation of several genes under both unstressed and stressed conditions. The numbers of genes under the AtfA control appear to be specific to a stress-type. We also found that both oxidative and salt stresses induced expression of some secondary metabolite gene clusters and the deletion of atfA enhanced the stress responsiveness of additional clusters. Moreover, certain clusters were down-regulated by the stresses tested.Our data suggest that the observed co-regulations were most likely consequences of the overlapping physiological effects of the stressors and not of the existence of a general environmental stress response. The function of AtfA in governing various stress responses is much smaller than anticipated and/or other regulators may play a redundant or overlapping role with AtfA. Both stress inducible and stress repressive regulations of secondary metabolism seem to be frequent features in A. nidulans.

SUBMITTER: Emri T

PROVIDER: S-EPMC4482186 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Core oxidative stress response in Aspergillus nidulans.

Emri Tamás T Szarvas Vera V Orosz Erzsébet E Antal Károly K Park HeeSoo H Han Kap-Hoon KH Yu Jae-Hyuk JH Pócsi István I

BMC genomics 20150627

<h4>Background</h4>The b-Zip transcription factor AtfA plays a key role in regulating stress responses in the filamentous fungus Aspergillus nidulans. To identify the core regulons of AtfA, we examined genome-wide expression changes caused by various stresses in the presence/absence of AtfA using A. nidulans microarrays. We also intended to address the intriguing question regarding the existence of core environmental stress response in this important model eukaryote.<h4>Results</h4>Examination o ...[more]

PMID: 26115917

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Project description:Genome wide transcriptional changes induced by various types of oxidative stresses as well as salt stress were studied in a DatfA mutant and the appropriate control A. nidulans strains. Although a significant number of stereotypically regulated genes was identified (Core Oxidative Stress Response or COSR genes) when the global transcriptional effects of five different oxidative stress conditions were compared the number of co-regulated genes decreased to 13 when NaCl stress was included into the analyses. The appearance of only a few co-regulated genes and the great number of genes regulated merely by one certain type of stress do not support the existence of a S. cerevisiae-type Environmental Stress Response in A. nidulans. Deletion of atfA, a true functional ortholog of fission yeast’s “all-purpose” stress response transcription factor, increased the oxidative stress sensitivity of A. nidulans and affected the transcription of several genes under both unstressed and stressed conditions. The number of genes under AtfA control was quite stress-type dependent; e.g. deletion of atfA altered the transcription of a wide spectrum of genes under menadione sodium bisulfite stress but had only a minor effect on the transcriptome profiles when A. nidulans cultures were exposed to H2O2, tBOOH, NaCl and, especially, to diamide stress. These observations suggest that the function of AtfA in the regulation of various stress responses is much smaller than we thought before or other transcription factors can take over a number of AtfA’s functions when the atfA gene is deleted. It is noteworthy that both oxidative and salt stress induced the transcription of some secondary metabolite gene clusters and the deletion of atfA enhanced the stress responsiveness of further clusters. Surprisingly, certain clusters were down-regulated by the stress conditions tested and the majority of them were not stress-responsive at all. Therefore, stress dependent regulation seems to be a frequent but far not a general feature of the regulation of secondary metabolism in A. nidulans.

Project description:Genome wide transcriptional changes induced by various types of oxidative stresses as well as salt stress were studied in a DatfA mutant and the appropriate control A. nidulans strains. Although a significant number of stereotypically regulated genes was identified (Core Oxidative Stress Response or COSR genes) when the global transcriptional effects of five different oxidative stress conditions were compared the number of co-regulated genes decreased to 13 when NaCl stress was included into the analyses. The appearance of only a few co-regulated genes and the great number of genes regulated merely by one certain type of stress do not support the existence of a S. cerevisiae-type Environmental Stress Response in A. nidulans. Deletion of atfA, a true functional ortholog of fission yeastâs âall-purposeâ stress response transcription factor, increased the oxidative stress sensitivity of A. nidulans and affected the transcription of several genes under both unstressed and stressed conditions. The number of genes under AtfA control was quite stress-type dependent; e.g. deletion of atfA altered the transcription of a wide spectrum of genes under menadione sodium bisulfite stress but had only a minor effect on the transcriptome profiles when A. nidulans cultures were exposed to H2O2, tBOOH, NaCl and, especially, to diamide stress. These observations suggest that the function of AtfA in the regulation of various stress responses is much smaller than we thought before or other transcription factors can take over a number of AtfAâs functions when the atfA gene is deleted. It is noteworthy that both oxidative and salt stress induced the transcription of some secondary metabolite gene clusters and the deletion of atfA enhanced the stress responsiveness of further clusters. Surprisingly, certain clusters were down-regulated by the stress conditions tested and the majority of them were not stress-responsive at all. Therefore, stress dependent regulation seems to be a frequent but far not a general feature of the regulation of secondary metabolism in A. nidulans. 14 samples, 7 with the control strain and 7 with an DatfA strain (each series contains samples from untreated as well as menadione, low concentration hidrogen-peroxide, high concentration hidrogen-peroxide, tert-butylhydroperoxide, diamide and NaCl treated cultures)

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Core oxidative stress response in Aspergillus nidulans.

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Core oxidative stress response in Aspergillus nidulans.

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