Characterization of a Putative F-box Motif in Ibd1p/Bfa1p, a Spindle Checkpoint Regulator of Budding Yeast Saccharomyces cerevisiae

Kyum Jung Lee, Hyung S. Hwang, Kiwon Song

Research output: Contribution to journalArticle

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Abstract

During mitosis, the proper segregation of duplicated chromosomes is coordinated by a spindle checkpoint. The bifurcated spindle checkpoint blocks cell cycle progression at metaphase by monitoring unattached kinetochores and inhibits mitotic exit in response to the misorientation of the mitotic spindle. Ibd1p/Bfa1p is a spindle checkpoint regulator of budding yeast in the Bub2p checkpoint pathway for mitotic exit and its disruption abolishes mitotic arrest when proper organization of the mitotic spindle is inhibited. Ibd1p/Bfa1p localizes to the spindle pole body, a microtubule-organizing center in yeast, and its overexpression arrests the cell cycle in 80% of cells with an enlarged bud at mitosis and in 20% of cells with multiple buds. In this study, we found that the C-terminus of Ibd1p/Bfa1p physically interacts with Skp1p, a key component of SCF (Skp1/cullin/F-box) complex for ubiquitin-mediated proteolysis of cell cycle regulators as well as an evolutionally conserved kinetochore protein for cell cycle progression. A putative F-box motif was found in the C-terminus of Ibd1p/Bfa1p and its function was investigated by making mutants of conserved residues in the motif. These Ibd1p/Bfa1p mutants of a putative F-box interacted with Skp1p in vitro by two-hybrid assays as wild type Ibd1p/Bfa1p. Also, these Ibd1p/Bfa1p mutants displayed the overexpression phenotypes of wild type Ibd1p, when overexpressed under inducible promoters. These results suggest that a putative F-box motif of Ibd1p/Bfa1p is not essential for the interaction with Skp1p and its function in mitotic exit and cytokinesis.

Original languageEnglish
Pages (from-to)286-292
Number of pages7
JournalJournal of Microbiology
Volume39
Issue number4
Publication statusPublished - 2001 Dec 1

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F-Box Motifs
Kinetochores
Spindle Apparatus
Saccharomycetales
Cell Cycle Checkpoints
Mitosis
Saccharomyces cerevisiae
Spindle Pole Bodies
Cullin Proteins
Microtubule-Organizing Center
M Phase Cell Cycle Checkpoints
Cell Cycle Proteins
Chromosome Segregation
Two-Hybrid System Techniques
Cytokinesis
Metaphase
Ubiquitin
Proteolysis
Cell Cycle
Yeasts

All Science Journal Classification (ASJC) codes

  • Applied Microbiology and Biotechnology
  • Microbiology

Cite this

@article{cfcee45153f44d0fb53d10b8a23fb4d6,
title = "Characterization of a Putative F-box Motif in Ibd1p/Bfa1p, a Spindle Checkpoint Regulator of Budding Yeast Saccharomyces cerevisiae",
abstract = "During mitosis, the proper segregation of duplicated chromosomes is coordinated by a spindle checkpoint. The bifurcated spindle checkpoint blocks cell cycle progression at metaphase by monitoring unattached kinetochores and inhibits mitotic exit in response to the misorientation of the mitotic spindle. Ibd1p/Bfa1p is a spindle checkpoint regulator of budding yeast in the Bub2p checkpoint pathway for mitotic exit and its disruption abolishes mitotic arrest when proper organization of the mitotic spindle is inhibited. Ibd1p/Bfa1p localizes to the spindle pole body, a microtubule-organizing center in yeast, and its overexpression arrests the cell cycle in 80{\%} of cells with an enlarged bud at mitosis and in 20{\%} of cells with multiple buds. In this study, we found that the C-terminus of Ibd1p/Bfa1p physically interacts with Skp1p, a key component of SCF (Skp1/cullin/F-box) complex for ubiquitin-mediated proteolysis of cell cycle regulators as well as an evolutionally conserved kinetochore protein for cell cycle progression. A putative F-box motif was found in the C-terminus of Ibd1p/Bfa1p and its function was investigated by making mutants of conserved residues in the motif. These Ibd1p/Bfa1p mutants of a putative F-box interacted with Skp1p in vitro by two-hybrid assays as wild type Ibd1p/Bfa1p. Also, these Ibd1p/Bfa1p mutants displayed the overexpression phenotypes of wild type Ibd1p, when overexpressed under inducible promoters. These results suggest that a putative F-box motif of Ibd1p/Bfa1p is not essential for the interaction with Skp1p and its function in mitotic exit and cytokinesis.",
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Characterization of a Putative F-box Motif in Ibd1p/Bfa1p, a Spindle Checkpoint Regulator of Budding Yeast Saccharomyces cerevisiae. / Lee, Kyum Jung; Hwang, Hyung S.; Song, Kiwon.

In: Journal of Microbiology, Vol. 39, No. 4, 01.12.2001, p. 286-292.

Research output: Contribution to journalArticle

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