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Ca2+-calmodulin antagonists interfere with xylanase formation and secretion in Trichoderma reesei
R L Mach1, S Zeilinger, D Kristufek
1Abteilung für Mikrobielle Biochemie, Institut für Biochemische Technologie und Mikrobiologie, TU Wien, Getreidemarkt 9/172-5, A-1060 Vienna, Austria.
Biochimica Et Biophysica Acta
|August 1, 1998
Summary
Calcium ions and calmodulin are essential for xylanase II formation in Trichoderma reesei. These factors regulate xylanase gene expression and protein processing through phosphorylation, impacting the secretory pathway.
Area of Science:
- Biochemistry
- Molecular Biology
- Mycology
Background:
- Xylanase enzymes are crucial for breaking down xylan, a major component of plant cell walls.
- The regulation of xylanase production in fungi like Trichoderma reesei is complex and involves various cellular signaling pathways.
- Calcium ions (Ca2+) and calmodulin are known to play roles in diverse cellular processes, including gene expression and protein secretion.
Purpose of the Study:
- To investigate the role of calcium ions (Ca2+) and calmodulin in the formation of xylanase II in Trichoderma reesei.
- To elucidate the specific mechanisms by which Ca2+ and calmodulin influence xylanase II production at transcriptional and post-transcriptional levels.
- To identify potential Ca2+-calmodulin-dependent phosphorylation events involved in xylanase II secretion.
Main Methods:
- Inhibition studies using Ca2+ antagonists, ionophores, and complexing agents.
- Application of calmodulin inhibitors (trifluoroperazine, chlorpromazine, quinacrine).
- Analysis of xyn2 transcript levels using Northern blotting or similar techniques.
- Gene fusion assays to study regulatory elements.
- Subcellular fractionation to localize protein accumulation.
- Investigation of protein phosphorylation in cell-free extracts.
Main Results:
- Calcium ions (Ca2+) and calmodulin are essential for xylanase II formation in Trichoderma reesei.
- Inhibition of calmodulin disrupted both xyn2 gene transcription and post-Golgi protein processing.
- Ca2+-calmodulin signaling appears to regulate xylanase II production at both transcriptional and secretory pathway stages.
- Evidence suggests Ca2+-calmodulin-dependent phosphorylation of a 20-kDa protein is involved.
Conclusions:
- Calmodulin is indispensable for xylanase II formation in T. reesei, acting at both transcriptional and post-Golgi secretory pathway levels.
- Ca2+-calmodulin signaling regulates xylanase II production through transcriptional control and post-translational modifications.
- Ca2+-calmodulin-dependent phosphorylation may mediate these regulatory steps, impacting enzyme secretion.