Dominant mutations affecting expression of pH-regulated genes inYarrowia lipolytica

Life, as we know it, is water based. Exposure to hydroxonium and hydroxide ions is constant and ubiquitous, and the evolutionary pressure to respond appropriately to these ions is likely to be intense. Fungi respond to their environments by tailoring their output of activities destined for the cell surface or beyond to the ambient pH. We are beginning to glimpse how they sense ambient pH and transmit this information to the transcription factor, whose roles ensure that a suitable collection of gene products will be made. Although relatively little is known about pH signal transduction itself, its consequences for the cognate transcription factor are much clearer. Intriguingly, homologues of components of this system mediating the regulation of fungal gene expression by ambient pH are to be found in the animal kingdom. The potential applied importance of this regulatory system lies in its key role in fungal pathogenicity of animals and plants and in its control of fungal production of toxins, antibiotics, and secreted enzymes

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“…This has been exploited by Gaillardin and colleagues to characterize the pHregulatory system of this dimorphic yeast (26,69,124).…”

Section: Regulation Of Protease Gene Expression By Ambient Phmentioning

confidence: 99%

Regulation of Gene Expression by Ambient pH in Filamentous Fungi and Yeasts

Peñalva

Arst

2002

Microbiol Mol Biol Rev

271

213

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“…have been identified and studied; the major mediator is the zinc finger transcription factor PacC, an activator for alkaline-expressed genes and a repressor for acid-expressed genes (10,14). Similarly, mutations affecting the expression of pH-regulated genes in Y. lipolytica have also been described (3). These studies should eventually lead to an understanding of how these organisms sense ambient pH.…”

mentioning

confidence: 99%

Ambient pH Is a Major Determinant in the Expression of Cuticle-Degrading Enzymes and Hydrophobin by Metarhizium anisopliae

Leger

Joshi

Roberts

1998

Appl Environ Microbiol

151

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Secretion of proteolytic and chitinolytic enzymes is a hallmark of infection processes of Metarhizium anisopliae in response to host (insect) cuticular signals. The regulation of these enzymes (subtilisin-like proteases [Pr1a and Pr1b], trypsin-like proteases [Pr2], metalloproteases, aspartyl proteases, aminopeptidase, and chitinases) and a hydrophobin was investigated by Northern analysis and/or enzyme assay. The production of each enzyme showed a differential expression pattern in response to ambient pH; enzymes were synthesized only at pHs at which they function effectively, irrespective of whether the medium contained an inductive cuticle substrate. Three aspartyl proteases (pH optimum, 3), and chitinase (pH optimum, 5) showed maximal accumulation at acidic pHs. The highest level of aminopeptidase (pH optimum, 7) was detected at pH 7. The highest levels of five metalloproteases (pH optima, ca. 7) were detected over the pH range 6 to 8. Two trypsins and several subtilisin-like Pr1 isoforms with pH optima of ca. 8 were produced only under alkaline conditions. Northern analysis of RNA species corresponding to seven cDNA sequences encoding proteases and chitinase confirmed that the ambient pH played a major role in gene expression of secreted proteins. Hydrophobin was expressed almost equally at pHs 5 and 8 but was not expressed at pH 3. During fungal penetration, the pH of infected cuticle rises from about 6.3 to 7.7. Consistent with pH regulation of enzyme production, serine and metalloproteases were produced in situ during infection, but no production of aspartyl proteases was found. We propose that the alkalinity of infected cuticle represents a physiological signal that triggers the production of virulence factors.

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Secretion and pH-dependent self-processing of the pro-form of the Yarrowia lipolytica acid extracellular protease

McEwen

Young

1998

Yeast

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Dominant mutations affecting expression of pH-regulated genes inYarrowia lipolytica

Cited by 7 publications

References 27 publications

Regulation of Gene Expression by Ambient pH in Filamentous Fungi and Yeasts

Regulation of Gene Expression by Ambient pH in Filamentous Fungi and Yeasts

Ambient pH Is a Major Determinant in the Expression of Cuticle-Degrading Enzymes and Hydrophobin by Metarhizium anisopliae

Secretion and pH-dependent self-processing of the pro-form of the Yarrowia lipolytica acid extracellular protease

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