Phosphorylation at Thr167 is required for Schizosaccharomyces pombe p34cdc2 function

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Eukaryotic cell cycle progression depends on regulated protein kinase activity.
• The fission yeast cdc2+ gene encodes a key protein-serine/threonine kinase, p34cdc2.
• p34cdc2 activity is modulated by phosphorylation, including at Tyr15, which regulates mitosis initiation.

Purpose of the Study:

• To identify the second phosphorylation site on fission yeast p34cdc2.
• To elucidate the regulatory role of this second phosphorylation site in p34cdc2 kinase activity.
• To investigate the involvement of Thr167 phosphorylation in p34cdc2 interactions and cell cycle progression.

Main Methods:

• Analysis of fission yeast cell phenotypes expressing mutations at position 167 of p34cdc2.
• In vitro biochemical experiments to assess p34cdc2 kinase activity and protein associations.
• Identification of Thr167 as a novel phosphorylation site on p34cdc2.

Main Results:

• Thr167 was identified as the second major phosphorylation site on p34cdc2.
• Phosphorylation of Thr167 is crucial for p34cdc2 kinase activity during mitosis.
• Thr167 phosphorylation is involved in the association of p34cdc2 with cyclin B.

Conclusions:

• The phosphorylation state of Thr167 is a critical regulator of p34cdc2 kinase activity.
• Thr167 phosphorylation plays a key role in controlling entry into mitosis.
• Dephosphorylation of Thr167 may also be involved in the exit from mitosis.