Limits...
The septins function in G1 pathways that influence the pattern of cell growth in budding yeast.

Egelhofer TA, Villén J, McCusker D, Gygi SP, Kellogg DR - PLoS ONE (2008)

Bottom Line: However, Shs1 phosphorylation site mutants do not show genetic interactions with the G1 cyclins or obvious defects early in the cell cycle.Shs1 phosphorylation mutants also show defects in interaction with the Gin4 kinase, which associates with the septins during G2/M and plays a role in regulating inhibitory phosphorylation of Cdk1.Phosphorylation of Shs1 by G1 cyclin-dependent kinases plays a role in events that influence Cdk1 inhibitory phosphorylation.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular, Cell and Developmental Biology, University of California Santa Cruz, Santa Cruz, California, United States of America.

ABSTRACT
The septins are a conserved family of proteins that have been proposed to carry out diverse functions. In budding yeast, the septins become localized to the site of bud emergence in G1 but have not been thought to carry out important functions at this stage of the cell cycle. We show here that the septins function in redundant mechanisms that are required for formation of the bud neck and for the normal pattern of cell growth early in the cell cycle. The Shs1 septin shows strong genetic interactions with G1 cyclins and is directly phosphorylated by G1 cyclin-dependent kinases, consistent with a role in early cell cycle events. However, Shs1 phosphorylation site mutants do not show genetic interactions with the G1 cyclins or obvious defects early in the cell cycle. Rather, they cause an increased cell size and aberrant cell morphology that are dependent upon inhibitory phosphorylation of Cdk1 at the G2/M transition. Shs1 phosphorylation mutants also show defects in interaction with the Gin4 kinase, which associates with the septins during G2/M and plays a role in regulating inhibitory phosphorylation of Cdk1. Phosphorylation of Shs1 by G1 cyclin-dependent kinases plays a role in events that influence Cdk1 inhibitory phosphorylation.

Show MeSH

Related in: MedlinePlus

Loss of Cdc12 or Shs1 in cln1Δ cln2Δ cells causes defects in formation of the bud neck and the pattern of growth.(A) cdc12-6, cln1Δ cln2Δ, and cdc12-6 cln1Δ cln2Δ cells were synchronized by centrifugal elutriation and released into YPD media at 34°C, the restrictive temperature for the cdc12-6 allele. Micrographs were taken at the indicated timepoints after release. Bar, 5 µm for all panels (B) Cells of the indicated genotypes were grown to log phase in YP media containing galactose and transferred to YPD media at 30°C. Micrographs were taken 4.5 hours after release into YPD media. Bar, 5 µm for both panels.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2291192&req=5

pone-0002022-g002: Loss of Cdc12 or Shs1 in cln1Δ cln2Δ cells causes defects in formation of the bud neck and the pattern of growth.(A) cdc12-6, cln1Δ cln2Δ, and cdc12-6 cln1Δ cln2Δ cells were synchronized by centrifugal elutriation and released into YPD media at 34°C, the restrictive temperature for the cdc12-6 allele. Micrographs were taken at the indicated timepoints after release. Bar, 5 µm for all panels (B) Cells of the indicated genotypes were grown to log phase in YP media containing galactose and transferred to YPD media at 30°C. Micrographs were taken 4.5 hours after release into YPD media. Bar, 5 µm for both panels.

Mentions: We used the cdc12-6 cln1Δ cln2Δ cells and the shs1Δ cln1Δ GAL1-CLN2 cells to determine the consequences of a loss of septin function in cells that lack Cln1 and Cln2. We first used centrifugal elutriation to synchronize cdc12-6, cln1Δ cln2Δ, and cdc12-6 cln1Δ cln2Δ cells in early G1 and then released them at the restrictive temperature for the cdc12-6 allele (34°C). The cdc12-6 cln1Δ cln2Δ cells were unable to form buds with normal morphology and largely failed to direct growth to the daughter bud (Figure 2A). The cells were also unable to form a normal bud neck with a well-defined constriction between the mother and daughter cell.


The septins function in G1 pathways that influence the pattern of cell growth in budding yeast.

Egelhofer TA, Villén J, McCusker D, Gygi SP, Kellogg DR - PLoS ONE (2008)

Loss of Cdc12 or Shs1 in cln1Δ cln2Δ cells causes defects in formation of the bud neck and the pattern of growth.(A) cdc12-6, cln1Δ cln2Δ, and cdc12-6 cln1Δ cln2Δ cells were synchronized by centrifugal elutriation and released into YPD media at 34°C, the restrictive temperature for the cdc12-6 allele. Micrographs were taken at the indicated timepoints after release. Bar, 5 µm for all panels (B) Cells of the indicated genotypes were grown to log phase in YP media containing galactose and transferred to YPD media at 30°C. Micrographs were taken 4.5 hours after release into YPD media. Bar, 5 µm for both panels.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2291192&req=5

pone-0002022-g002: Loss of Cdc12 or Shs1 in cln1Δ cln2Δ cells causes defects in formation of the bud neck and the pattern of growth.(A) cdc12-6, cln1Δ cln2Δ, and cdc12-6 cln1Δ cln2Δ cells were synchronized by centrifugal elutriation and released into YPD media at 34°C, the restrictive temperature for the cdc12-6 allele. Micrographs were taken at the indicated timepoints after release. Bar, 5 µm for all panels (B) Cells of the indicated genotypes were grown to log phase in YP media containing galactose and transferred to YPD media at 30°C. Micrographs were taken 4.5 hours after release into YPD media. Bar, 5 µm for both panels.
Mentions: We used the cdc12-6 cln1Δ cln2Δ cells and the shs1Δ cln1Δ GAL1-CLN2 cells to determine the consequences of a loss of septin function in cells that lack Cln1 and Cln2. We first used centrifugal elutriation to synchronize cdc12-6, cln1Δ cln2Δ, and cdc12-6 cln1Δ cln2Δ cells in early G1 and then released them at the restrictive temperature for the cdc12-6 allele (34°C). The cdc12-6 cln1Δ cln2Δ cells were unable to form buds with normal morphology and largely failed to direct growth to the daughter bud (Figure 2A). The cells were also unable to form a normal bud neck with a well-defined constriction between the mother and daughter cell.

Bottom Line: However, Shs1 phosphorylation site mutants do not show genetic interactions with the G1 cyclins or obvious defects early in the cell cycle.Shs1 phosphorylation mutants also show defects in interaction with the Gin4 kinase, which associates with the septins during G2/M and plays a role in regulating inhibitory phosphorylation of Cdk1.Phosphorylation of Shs1 by G1 cyclin-dependent kinases plays a role in events that influence Cdk1 inhibitory phosphorylation.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular, Cell and Developmental Biology, University of California Santa Cruz, Santa Cruz, California, United States of America.

ABSTRACT
The septins are a conserved family of proteins that have been proposed to carry out diverse functions. In budding yeast, the septins become localized to the site of bud emergence in G1 but have not been thought to carry out important functions at this stage of the cell cycle. We show here that the septins function in redundant mechanisms that are required for formation of the bud neck and for the normal pattern of cell growth early in the cell cycle. The Shs1 septin shows strong genetic interactions with G1 cyclins and is directly phosphorylated by G1 cyclin-dependent kinases, consistent with a role in early cell cycle events. However, Shs1 phosphorylation site mutants do not show genetic interactions with the G1 cyclins or obvious defects early in the cell cycle. Rather, they cause an increased cell size and aberrant cell morphology that are dependent upon inhibitory phosphorylation of Cdk1 at the G2/M transition. Shs1 phosphorylation mutants also show defects in interaction with the Gin4 kinase, which associates with the septins during G2/M and plays a role in regulating inhibitory phosphorylation of Cdk1. Phosphorylation of Shs1 by G1 cyclin-dependent kinases plays a role in events that influence Cdk1 inhibitory phosphorylation.

Show MeSH
Related in: MedlinePlus