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Yeast chitin synthase 2 activity is modulated by proteolysis and phosphorylation
Fuensanta W Martínez-Rucobo1, Luise Eckhardt-Strelau, Anke C Terwisscha van Scheltinga
1Max Planck Institute of Biophysics, Department of Structural Biology, Max-von-Laue-Strasse 3, Frankfurt am Main, Germany.
The Biochemical Journal
|October 1, 2008
Summary
Saccharomyces cerevisiae Chs2 (chitin synthase 2) is regulated by a yeast protease and N-terminal phosphorylation. These mechanisms control its activity and stability, crucial for cell division and separation.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Saccharomyces cerevisiae Chs2 (chitin synthase 2) is vital for cell separation after mitosis.
- Chs2 activity is expected to be tightly regulated due to its essential role.
Purpose of the Study:
- To investigate the regulatory mechanisms of Saccharomyces cerevisiae Chs2.
- To identify factors influencing Chs2 activity and stability.
Main Methods:
- Expression and purification of active Chs2 and a mutant in Pichia pastoris.
- Biochemical analysis including pH, cation dependence, and trypsin treatment.
- LC-MS/MS for identification of phosphorylation sites and protease activity assays.
Main Results:
- Chs2 exhibits pH and cation dependence, with activity enhanced by trypsin.
- A soluble yeast protease hyperactivates Chs2, particularly during the exponential growth phase.
- LC-MS/MS identified 12 phosphorylation sites in the N-terminal domain, four matching the Cdk1 motif.
- N-terminal phosphorylation is crucial for Chs2 stability.
Conclusions:
- Chitin synthase 2 is regulated by both protease-mediated activation and phosphorylation.
- Protease activation is linked to cellular growth phases requiring Chs2 activity.
- Phosphorylation sites, particularly those targeted by Cdk1, likely mediate cell cycle-dependent degradation and influence enzyme stability, impacting cell division.
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