Interconnections between the Cation/Alkaline pH-Responsive Slt and the Ambient pH Response of PacC/Pal Pathways in <i>Aspergillus nidulans</i>
In the filamentous ascomycete <i>Aspergillus nidulans</i>, at least three high hierarchy transcription factors are required for growth at extracellular alkaline pH: SltA, PacC and CrzA. Transcriptomic profiles depending on alkaline pH and SltA function showed that <i>pacC</i>...
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MDPI AG
2024-04-01
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| Series: | Cells |
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| Online Access: | https://www.mdpi.com/2073-4409/13/7/651 |
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| author | Irene Picazo Eduardo A. Espeso |
| author_facet | Irene Picazo Eduardo A. Espeso |
| author_sort | Irene Picazo |
| collection | DOAJ |
| description | In the filamentous ascomycete <i>Aspergillus nidulans</i>, at least three high hierarchy transcription factors are required for growth at extracellular alkaline pH: SltA, PacC and CrzA. Transcriptomic profiles depending on alkaline pH and SltA function showed that <i>pacC</i> expression might be under SltA regulation. Additional transcriptional studies of PacC and the only pH-regulated <i>pal</i> gene, <i>palF</i>, confirmed both the strong dependence on ambient pH and the function of SltA. The regulation of <i>pacC</i> expression is dependent on the activity of the zinc binuclear (C6) cluster transcription factor PacX. However, we found that the ablation of <i>sltA</i> in the <i>pacX<sup>−</sup></i> mutant background specifically prevents the increase in <i>pacC</i> expression levels without affecting PacC protein levels, showing a novel specific function of the PacX factor. The loss of <i>sltA</i> function causes the anomalous proteolytic processing of PacC and a reduction in the post-translational modifications of PalF. At alkaline pH, in a null <i>sltA</i> background, PacC<sup>72kDa</sup> accumulates, detection of the intermediate PacC<sup>53kDa</sup> form is extremely low and the final processed form of 27 kDa shows altered electrophoretic mobility. Constitutive ubiquitination of PalF or the presence of alkalinity-mimicking mutations in <i>pacC</i>, such as <i>pacC<sup>c</sup>14</i> and <i>pacC<sup>c</sup>700</i>, resembling PacC<sup>53kDa</sup> and PacC<sup>27kDa</sup>, respectively, allowed the normal processing of PacC but did not rescue the alkaline pH-sensitive phenotype caused by the null <i>sltA</i> allele. Overall, data show that Slt and PacC/Pal pathways are interconnected, but the transcription factor SltA is on a higher hierarchical level than PacC on regulating the tolerance to the ambient alkalinity in <i>A. nidulans</i>. |
| first_indexed | 2024-04-24T10:48:04Z |
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| institution | Directory Open Access Journal |
| issn | 2073-4409 |
| language | English |
| last_indexed | 2024-04-24T10:48:04Z |
| publishDate | 2024-04-01 |
| publisher | MDPI AG |
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| spelling | doaj.art-a5393000e9ed4de5a9ff365a25cb1eb52024-04-12T13:16:38ZengMDPI AGCells2073-44092024-04-0113765110.3390/cells13070651Interconnections between the Cation/Alkaline pH-Responsive Slt and the Ambient pH Response of PacC/Pal Pathways in <i>Aspergillus nidulans</i>Irene Picazo0Eduardo A. Espeso1Department of Molecular and Cellular Biology, Centro de Investigaciones Biológicas (CIB) Margarita Salas, Spanish Research Council (CSIC), Ramiro de Maeztu, 9, 28040 Madrid, SpainDepartment of Molecular and Cellular Biology, Centro de Investigaciones Biológicas (CIB) Margarita Salas, Spanish Research Council (CSIC), Ramiro de Maeztu, 9, 28040 Madrid, SpainIn the filamentous ascomycete <i>Aspergillus nidulans</i>, at least three high hierarchy transcription factors are required for growth at extracellular alkaline pH: SltA, PacC and CrzA. Transcriptomic profiles depending on alkaline pH and SltA function showed that <i>pacC</i> expression might be under SltA regulation. Additional transcriptional studies of PacC and the only pH-regulated <i>pal</i> gene, <i>palF</i>, confirmed both the strong dependence on ambient pH and the function of SltA. The regulation of <i>pacC</i> expression is dependent on the activity of the zinc binuclear (C6) cluster transcription factor PacX. However, we found that the ablation of <i>sltA</i> in the <i>pacX<sup>−</sup></i> mutant background specifically prevents the increase in <i>pacC</i> expression levels without affecting PacC protein levels, showing a novel specific function of the PacX factor. The loss of <i>sltA</i> function causes the anomalous proteolytic processing of PacC and a reduction in the post-translational modifications of PalF. At alkaline pH, in a null <i>sltA</i> background, PacC<sup>72kDa</sup> accumulates, detection of the intermediate PacC<sup>53kDa</sup> form is extremely low and the final processed form of 27 kDa shows altered electrophoretic mobility. Constitutive ubiquitination of PalF or the presence of alkalinity-mimicking mutations in <i>pacC</i>, such as <i>pacC<sup>c</sup>14</i> and <i>pacC<sup>c</sup>700</i>, resembling PacC<sup>53kDa</sup> and PacC<sup>27kDa</sup>, respectively, allowed the normal processing of PacC but did not rescue the alkaline pH-sensitive phenotype caused by the null <i>sltA</i> allele. Overall, data show that Slt and PacC/Pal pathways are interconnected, but the transcription factor SltA is on a higher hierarchical level than PacC on regulating the tolerance to the ambient alkalinity in <i>A. nidulans</i>.https://www.mdpi.com/2073-4409/13/7/651signallingpost-translational modificationstranscriptional factorscross regulationabiotic stress |
| spellingShingle | Irene Picazo Eduardo A. Espeso Interconnections between the Cation/Alkaline pH-Responsive Slt and the Ambient pH Response of PacC/Pal Pathways in <i>Aspergillus nidulans</i> Cells signalling post-translational modifications transcriptional factors cross regulation abiotic stress |
| title | Interconnections between the Cation/Alkaline pH-Responsive Slt and the Ambient pH Response of PacC/Pal Pathways in <i>Aspergillus nidulans</i> |
| title_full | Interconnections between the Cation/Alkaline pH-Responsive Slt and the Ambient pH Response of PacC/Pal Pathways in <i>Aspergillus nidulans</i> |
| title_fullStr | Interconnections between the Cation/Alkaline pH-Responsive Slt and the Ambient pH Response of PacC/Pal Pathways in <i>Aspergillus nidulans</i> |
| title_full_unstemmed | Interconnections between the Cation/Alkaline pH-Responsive Slt and the Ambient pH Response of PacC/Pal Pathways in <i>Aspergillus nidulans</i> |
| title_short | Interconnections between the Cation/Alkaline pH-Responsive Slt and the Ambient pH Response of PacC/Pal Pathways in <i>Aspergillus nidulans</i> |
| title_sort | interconnections between the cation alkaline ph responsive slt and the ambient ph response of pacc pal pathways in i aspergillus nidulans i |
| topic | signalling post-translational modifications transcriptional factors cross regulation abiotic stress |
| url | https://www.mdpi.com/2073-4409/13/7/651 |
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