Proteolytic activation of both components of the cation-stress responsive Slt pathway in Aspergillus nidulans
File(s)
Published version
Author(s)
Arst, HN
Mellado, L
Espeso, EA
Type
Journal Article
Abstract
Tolerance of Aspergillus nidulans to alkalinity and elevated cation concentrations requires both SltA and SltB. Transcription factor SltA and the putative pseudo-kinase/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 auto-proteolysis and the proteolytic cleavage of SltA. The pseudo-kinase domain might modulate the protease activity of SltB. Three forms of the SltA transcription factor coexist in cells, a full-length 78kDa version and a processed 32kDa 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.
Date Issued
2016-08-15
Date Acceptance
2016-06-11
Citation
Molecular Biology of the Cell, 2016, 27 (16), pp.2598-2612
ISSN
1939-4586
Publisher
American Society for Cell Biology
Start Page
2598
End Page
2612
Journal / Book Title
Molecular Biology of the Cell
Volume
27
Issue
16
Copyright Statement
© 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)
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)
License URL
Sponsor
Anonymous Donor
Grant Number
RX0007RFD
Subjects
Developmental Biology
06 Biological Sciences
11 Medical And Health Sciences
Publication Status
Published