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Updated: Oct 1, 2026
Spatiotemporal Analysis of Cytokinetic Events in Fission Yeast
Published on: February 20, 2017
The spindle pole body protein Cdc11p links Sid4p to the fission yeast septation initiation network
Gregory C Tomlin1, Jennifer L Morrell, Kathleen L Gould
1HHMI and Department of Cell Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232.
Insights
Cdc11p links the septation initiation network (SIN) to cell division signaling in Schizosaccharomyces pombe. This protein localizes SIN components to the spindle pole body (SPB), connecting Sid4p and Spg1p pathways for proper cell division.
Area of Science:
- Cell biology
- Molecular genetics
- Fission yeast research
Background:
- The septation initiation network (SIN) regulates cell division in Schizosaccharomyces pombe.
- SIN component localization to the spindle pole body (SPB) is crucial for cytokinesis.
- Sid4p is a constitutive SPB resident, but its direct interaction with other SIN components is unknown.
Purpose of the Study:
- To investigate the role of a novel SPB protein, Cdc11p, in the SIN.
- To elucidate the mechanism linking Sid4p to other SIN components.
- To understand how Cdc11p integrates into the Spg1p signaling pathway.
Main Methods:
- Characterization of the S. pombe Nud1p homolog, Cdc11p.
- Analysis of Cdc11p localization and function at the SPB.
- Demonstration of direct protein-protein interactions using biochemical assays.
Main Results:
- Cdc11p is a constitutively present SPB component essential for the localization of most SIN proteins.
- The C terminus of Cdc11p mediates SPB localization dependent on Sid4p.
- A direct interaction between Cdc11p and Sid4p was confirmed.
- The N terminus of Cdc11p is required for Spg1p binding to the SPB.
Conclusions:
- Cdc11p acts as a crucial scaffold protein within the S. pombe SIN.
- Cdc11p physically connects the Sid4p-dependent SPB localization mechanism with the Spg1p signaling cascade.
- This interaction is vital for the proper initiation of cell division.
Abstract:
The Schizosaccharomyces pombe septation initiation network (SIN) signals the onset of cell division from the spindle pole body (SPB) and is regulated by the small GTPase Spg1p. The localization of SIN components including Spg1p to the SPB is required for cytokinesis and is dependent on Sid4p, a constitutive resident of SPBs. However, a direct interaction between Sid4p and other members of the SIN has not been detected. To understand how Sid4p is linked to other SIN components, we have begun to characterize an S. pombe homolog of the Saccharomyces cerevisiae SPB protein Nud1p. We have determined that this S. pombe Nud1p homolog corresponds to Cdc11p, a previously uncharacterized SIN element. We report that Cdc11p is present constitutively at SPBs and that its function appears to be required for the localization of all other SIN components to SPBs with the exception of Sid4p. The Cdc11p C terminus localizes the protein to SPBs in a Sid4p-dependent manner, and we demonstrate a direct Cdc11p-Sid4p interaction. The N-terminus of Cdc11p is required for Spg1p binding to SPBs. Our studies indicate that Cdc11p provides a physical link between Sid4p and the Spg1p signaling pathway.
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