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Mol Biol Cell. 2014 Sep 15;25(18):2735-49. doi: 10.1091/mbc.E13-11-0699. Epub 2014 Jul 16.

Regulation of spindle pole body assembly and cytokinesis by the centrin-binding protein Sfi1 in fission yeast.

Author information

1
Graduate Program of Molecular, Cellular, and Developmental Biology, The Ohio State University, Columbus, OH 43210 Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210.
2
Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210.
3
National Institute of Biological Sciences, Beijing 102206, China.
4
Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, United Kingdom.
5
Department of Molecular, Cellular, and Developmental Biology, University of Colorado-Boulder, Boulder, CO 80309.
6
Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305.
7
Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210 Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, OH 43210 wu.620@osu.edu.

Abstract

Centrosomes play critical roles in the cell division cycle and ciliogenesis. Sfi1 is a centrin-binding protein conserved from yeast to humans. Budding yeast Sfi1 is essential for the initiation of spindle pole body (SPB; yeast centrosome) duplication. However, the recruitment and partitioning of Sfi1 to centrosomal structures have never been fully investigated in any organism, and the presumed importance of the conserved tryptophans in the internal repeats of Sfi1 remains untested. Here we report that in fission yeast, instead of doubling abruptly at the initiation of SPB duplication and remaining at a constant level thereafter, Sfi1 is gradually recruited to SPBs throughout the cell cycle. Like an sfi1Δ mutant, a Trp-to-Arg mutant (sfi1-M46) forms monopolar spindles and exhibits mitosis and cytokinesis defects. Sfi1-M46 protein associates preferentially with one of the two daughter SPBs during mitosis, resulting in a failure of new SPB assembly in the SPB receiving insufficient Sfi1. Although all five conserved tryptophans tested are involved in Sfi1 partitioning, the importance of the individual repeats in Sfi1 differs. In summary, our results reveal a link between the conserved tryptophans and Sfi1 partitioning and suggest a revision of the model for SPB assembly.

PMID:
25031431
PMCID:
PMC4161509
DOI:
10.1091/mbc.E13-11-0699
[Indexed for MEDLINE]
Free PMC Article

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