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Multiple Ca2+/calmodulin-dependent protein kinase genes in a unicellular eukaryote
M H Pausch1, D Kaim, R Kunisawa
1Division of Biochemistry and Molecular Biology, University of California, Berkeley 94720.
The EMBO Journal
|June 1, 1991
Summary
Researchers identified two calcium/calmodulin-dependent protein kinase genes (CMK1 and CMK2) in Saccharomyces cerevisiae. Deleting these genes did not prove lethal, though CMK2 deletion impacted spore germination.
Area of Science:
- Molecular Biology
- Biochemistry
- Yeast Genetics
Background:
- Calcium/calmodulin-dependent protein kinases (CaM kinases) are crucial signaling enzymes in eukaryotes.
- Mammalian CaM kinases have well-characterized roles, but their counterparts in yeast are less understood.
- Investigating yeast CaM kinases can provide insights into conserved cellular functions.
Purpose of the Study:
- To identify and characterize CaM-dependent protein kinases in the yeast Saccharomyces cerevisiae.
- To determine the functional significance of these kinases in yeast cell growth and development.
Main Methods:
- Purification of a CaM kinase from yeast.
- Gene cloning using degenerate oligonucleotides and lambda gt11 screening.
- Homology analysis of the cloned gene with vertebrate CaM kinases.
- Gene deletion studies (cmk1 delta, cmk2 delta) and analysis of resulting phenotypes.
- Western blot analysis using specific antisera.
Main Results:
- A CaM kinase (CaM kinase) was purified from yeast, showing similarity to mammalian type II CaM kinases.
- The gene encoding the 55 kd subunit, CMK1, was cloned and found to be homologous to vertebrate CaM kinase II genes.
- Overexpression or deletion of CMK1 did not significantly affect yeast cell growth.
- Residual Ca2+/CaM-dependent protein kinase activity was observed in cmk1 delta cells.
- A second, highly similar gene, CMK2, was identified.
- Deletion of CMK2, or both CMK1 and CMK2, was not lethal, but CMK2 deletion slowed spore germination.
Conclusions:
- Saccharomyces cerevisiae possesses at least two CaM-dependent protein kinases, CMK1 and CMK2.
- These kinases are not essential for vegetative growth but play a role in spore germination (CMK2).
- The identified yeast CaM kinases share structural and functional similarities with their mammalian counterparts, suggesting conserved roles in cellular signaling.