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Proteolytic activation of both components of the cation stress–responsive Slt pathway in Aspergillus nidulans

Tolerance of Aspergillus nidulans to alkalinity and elevated cation concentrations requires both SltA and SltB. Transcription factor SltA and the putative pseudokinase/protease signaling protein SltB comprise a regulatory pathway specific to filamentous fungi. In vivo, SltB is proteolytically cleave...

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Autores principales: Mellado, Laura, Arst, Herbert N., Espeso, Eduardo A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The American Society for Cell Biology 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4985261/
https://www.ncbi.nlm.nih.gov/pubmed/27307585
http://dx.doi.org/10.1091/mbc.E16-01-0049
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author Mellado, Laura
Arst, Herbert N.
Espeso, Eduardo A.
author_facet Mellado, Laura
Arst, Herbert N.
Espeso, Eduardo A.
author_sort Mellado, Laura
collection PubMed
description Tolerance of Aspergillus nidulans to alkalinity and elevated cation concentrations requires both SltA and SltB. Transcription factor SltA and the putative pseudokinase/protease signaling protein SltB comprise a regulatory pathway specific to filamentous fungi. In vivo, SltB is proteolytically cleaved into its two principal domains. Mutational analysis defines a chymotrypsin-like serine protease domain that mediates SltB autoproteolysis and proteolytic cleavage of SltA. The pseudokinase domain might modulate the protease activity of SltB. Three forms of the SltA transcription factor coexist in cells: a full-length, 78-kDa version and a processed, 32-kDa form, which is found in phosphorylated and unphosphorylated states. The SltA32kDa version mediates transcriptional regulation of sltB and, putatively, genes required for tolerance to cation stress and alkalinity. The full-length form, SltA78kDa, apparently has no transcriptional function. In the absence of SltB, only the primary product of SltA is detectable, and its level equals that of SltA78kDa. Mutations in sltB selected as suppressors of null vps alleles and resulting in cation/alkalinity sensitivity either reduced or eliminated SltA proteolysis. There is no evidence for cation or alkalinity regulation of SltB cleavage, but activation of sltB expression requires SltA. This work identifies the molecular mechanisms governing the Slt pathway.
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spelling pubmed-49852612016-10-30 Proteolytic activation of both components of the cation stress–responsive Slt pathway in Aspergillus nidulans Mellado, Laura Arst, Herbert N. Espeso, Eduardo A. Mol Biol Cell Articles Tolerance of Aspergillus nidulans to alkalinity and elevated cation concentrations requires both SltA and SltB. Transcription factor SltA and the putative pseudokinase/protease signaling protein SltB comprise a regulatory pathway specific to filamentous fungi. In vivo, SltB is proteolytically cleaved into its two principal domains. Mutational analysis defines a chymotrypsin-like serine protease domain that mediates SltB autoproteolysis and proteolytic cleavage of SltA. The pseudokinase domain might modulate the protease activity of SltB. Three forms of the SltA transcription factor coexist in cells: a full-length, 78-kDa version and a processed, 32-kDa form, which is found in phosphorylated and unphosphorylated states. The SltA32kDa version mediates transcriptional regulation of sltB and, putatively, genes required for tolerance to cation stress and alkalinity. The full-length form, SltA78kDa, apparently has no transcriptional function. In the absence of SltB, only the primary product of SltA is detectable, and its level equals that of SltA78kDa. Mutations in sltB selected as suppressors of null vps alleles and resulting in cation/alkalinity sensitivity either reduced or eliminated SltA proteolysis. There is no evidence for cation or alkalinity regulation of SltB cleavage, but activation of sltB expression requires SltA. This work identifies the molecular mechanisms governing the Slt pathway. The American Society for Cell Biology 2016-08-15 /pmc/articles/PMC4985261/ /pubmed/27307585 http://dx.doi.org/10.1091/mbc.E16-01-0049 Text en © 2016 Mellado et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0). “ASCB®,” “The American Society for Cell Biology®,” and “Molecular Biology of the Cell®” are registered trademarks of The American Society for Cell Biology.
spellingShingle Articles
Mellado, Laura
Arst, Herbert N.
Espeso, Eduardo A.
Proteolytic activation of both components of the cation stress–responsive Slt pathway in Aspergillus nidulans
title Proteolytic activation of both components of the cation stress–responsive Slt pathway in Aspergillus nidulans
title_full Proteolytic activation of both components of the cation stress–responsive Slt pathway in Aspergillus nidulans
title_fullStr Proteolytic activation of both components of the cation stress–responsive Slt pathway in Aspergillus nidulans
title_full_unstemmed Proteolytic activation of both components of the cation stress–responsive Slt pathway in Aspergillus nidulans
title_short Proteolytic activation of both components of the cation stress–responsive Slt pathway in Aspergillus nidulans
title_sort proteolytic activation of both components of the cation stress–responsive slt pathway in aspergillus nidulans
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4985261/
https://www.ncbi.nlm.nih.gov/pubmed/27307585
http://dx.doi.org/10.1091/mbc.E16-01-0049
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