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Mid2p stabilizes septin rings during cytokinesis in fission yeast.

Berlin A, Paoletti A, Chang F - J. Cell Biol. (2003)

Bottom Line: In wild-type cells, septins assembled first during mitosis in a single ring and during septation developed into double rings that did not contract.No genetic interactions were found between mid2 and the related gene mid1.Thus, these studies identify a new factor responsible for the proper stability and function of septins during cytokinesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.

ABSTRACT
Septins are filament-forming proteins with a conserved role in cytokinesis. In the fission yeast Schizosaccharomyces pombe, septin rings appear to be involved primarily in cell-cell separation, a late stage in cytokinesis. Here, we identified a protein Mid2p on the basis of its sequence similarity to S. pombe Mid1p, Saccharomyces cerevisiae Bud4p, and Candida albicans Int1p. Like septin mutants, mid2delta mutants had delays in cell-cell separation. mid2delta mutants were defective in septin organization but not contractile ring closure or septum formation. In wild-type cells, septins assembled first during mitosis in a single ring and during septation developed into double rings that did not contract. In mid2delta cells, septins initially assembled in a single ring but during septation appeared in the cleavage furrow, forming a washer or disc structure. FRAP studies showed that septins are stable in wild-type cells but exchange 30-fold more rapidly in mid2delta cells. Mid2p colocalized with septins and required septins for its localization. A COOH-terminal pleckstrin homology domain of Mid2p was required for its localization and function. No genetic interactions were found between mid2 and the related gene mid1. Thus, these studies identify a new factor responsible for the proper stability and function of septins during cytokinesis.

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Mid2p is similar to Mid1p, Bud4p, and Int1p. Multiprotein alignment of the homologous COOH-terminal regions. Boxed region indicates the PH domains.
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fig1: Mid2p is similar to Mid1p, Bud4p, and Int1p. Multiprotein alignment of the homologous COOH-terminal regions. Boxed region indicates the PH domains.

Mentions: Mid2p was identified in a BLAST search of the S. pombe genome databases (Sanger Centre, Cambridge, UK) on the basis of its significant amino acid similarity to S. pombe Mid1p (19% identical residues, 37% similar, expect value 2e−05) (Altschul et al., 1990; Sohrmann et al., 1996; Tatusova and Madden, 1999). Mid2p also possess significant homology to S. cerevisiae Bud4p (20% identical, 38% similar, expect value 7e−13), and C. albicans Int1p (25% identical, 47% similar in the COOH-terminal 336 aa, expect value 4e−24) (Gale et al., 1996; Sanders and Herskowitz, 1996). All of these proteins possess a pleckstrin homology (PH)* domain at their very COOH terminus and share similarity in an adjacent region at the COOH terminus (Fig. 1). Mid1p and Bud4p also share homology through the entire length of Mid2p.


Mid2p stabilizes septin rings during cytokinesis in fission yeast.

Berlin A, Paoletti A, Chang F - J. Cell Biol. (2003)

Mid2p is similar to Mid1p, Bud4p, and Int1p. Multiprotein alignment of the homologous COOH-terminal regions. Boxed region indicates the PH domains.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172768&req=5

fig1: Mid2p is similar to Mid1p, Bud4p, and Int1p. Multiprotein alignment of the homologous COOH-terminal regions. Boxed region indicates the PH domains.
Mentions: Mid2p was identified in a BLAST search of the S. pombe genome databases (Sanger Centre, Cambridge, UK) on the basis of its significant amino acid similarity to S. pombe Mid1p (19% identical residues, 37% similar, expect value 2e−05) (Altschul et al., 1990; Sohrmann et al., 1996; Tatusova and Madden, 1999). Mid2p also possess significant homology to S. cerevisiae Bud4p (20% identical, 38% similar, expect value 7e−13), and C. albicans Int1p (25% identical, 47% similar in the COOH-terminal 336 aa, expect value 4e−24) (Gale et al., 1996; Sanders and Herskowitz, 1996). All of these proteins possess a pleckstrin homology (PH)* domain at their very COOH terminus and share similarity in an adjacent region at the COOH terminus (Fig. 1). Mid1p and Bud4p also share homology through the entire length of Mid2p.

Bottom Line: In wild-type cells, septins assembled first during mitosis in a single ring and during septation developed into double rings that did not contract.No genetic interactions were found between mid2 and the related gene mid1.Thus, these studies identify a new factor responsible for the proper stability and function of septins during cytokinesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.

ABSTRACT
Septins are filament-forming proteins with a conserved role in cytokinesis. In the fission yeast Schizosaccharomyces pombe, septin rings appear to be involved primarily in cell-cell separation, a late stage in cytokinesis. Here, we identified a protein Mid2p on the basis of its sequence similarity to S. pombe Mid1p, Saccharomyces cerevisiae Bud4p, and Candida albicans Int1p. Like septin mutants, mid2delta mutants had delays in cell-cell separation. mid2delta mutants were defective in septin organization but not contractile ring closure or septum formation. In wild-type cells, septins assembled first during mitosis in a single ring and during septation developed into double rings that did not contract. In mid2delta cells, septins initially assembled in a single ring but during septation appeared in the cleavage furrow, forming a washer or disc structure. FRAP studies showed that septins are stable in wild-type cells but exchange 30-fold more rapidly in mid2delta cells. Mid2p colocalized with septins and required septins for its localization. A COOH-terminal pleckstrin homology domain of Mid2p was required for its localization and function. No genetic interactions were found between mid2 and the related gene mid1. Thus, these studies identify a new factor responsible for the proper stability and function of septins during cytokinesis.

Show MeSH
Related in: MedlinePlus