Limits...
Vesicle docking to the spindle pole body is necessary to recruit the exocyst during membrane formation in Saccharomyces cerevisiae.

Mathieson EM, Suda Y, Nickas M, Snydsman B, Davis TN, Muller EG, Neiman AM - Mol. Biol. Cell (2010)

Bottom Line: During meiosis II in Saccharomyces cerevisiae, the cytoplasmic face of the spindle pole body, referred to as the meiosis II outer plaque (MOP), is modified in both composition and structure to become the initiation site for de novo formation of a membrane called the prospore membrane.The N-termini of two proteins, Mpc54p and Spo21p, were oriented toward the outer surface of the structure.Mutations in the N-terminus of Mpc54p resulted in a unique phenotype: precursor vesicles loosely tethered to the MOP but did not contact its surface.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA.

ABSTRACT
During meiosis II in Saccharomyces cerevisiae, the cytoplasmic face of the spindle pole body, referred to as the meiosis II outer plaque (MOP), is modified in both composition and structure to become the initiation site for de novo formation of a membrane called the prospore membrane. The MOP serves as a docking complex for precursor vesicles that are targeted to its surface. Using fluorescence resonance energy transfer analysis, the orientation of coiled-coil proteins within the MOP has been determined. The N-termini of two proteins, Mpc54p and Spo21p, were oriented toward the outer surface of the structure. Mutations in the N-terminus of Mpc54p resulted in a unique phenotype: precursor vesicles loosely tethered to the MOP but did not contact its surface. Thus, these mpc54 mutants separate the steps of vesicle association and docking. Using these mpc54 mutants, we determined that recruitment of the Rab GTPase Sec4p, as well as the exocyst components Sec3p and Sec8p, to the precursor vesicles requires vesicle docking to the MOP. This suggests that the MOP promotes membrane formation both by localization of precursor vesicles to a particular site and by recruitment of a second tethering complex, the exocyst, that stimulates downstream events of fusion.

Show MeSH

Related in: MedlinePlus

Mpc54p plays a role in vesicle docking. Representative examples of TEM images of the MOP in single sections of meiosis II spindle pole bodies. Vesicles flush against the surface of the MOP are indicated with a red arrow. Loosely tethered vesicles are indicated with a blue arrow. Electron-dense projections between the MOP and tethered vesicles are indicated with a yellow arrow. Scale bars for whole cell images, 500 nm. Scale bars for higher magnification images, 100 nm.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2965686&req=5

Figure 6: Mpc54p plays a role in vesicle docking. Representative examples of TEM images of the MOP in single sections of meiosis II spindle pole bodies. Vesicles flush against the surface of the MOP are indicated with a red arrow. Loosely tethered vesicles are indicated with a blue arrow. Electron-dense projections between the MOP and tethered vesicles are indicated with a yellow arrow. Scale bars for whole cell images, 500 nm. Scale bars for higher magnification images, 100 nm.

Mentions: The fluorescence data suggested that the composition of the MOP was not disrupted by the mpc54 point mutations (Figure 4B). To examine this possibility more closely, thin-section TEM analysis was used to analyze the structure of the MOP as well as the stages of prospore membrane formation in fine detail. Analysis of cells expressing the mpc54 mutants revealed that the MOPs displayed the distinct, layered morphology of wild-type MOPs (Figure 6). This clearly defined MOP structure was absent in the mpc54Δ mutant (Figure 6). These results support the finding that mpc54 mutant alleles maintain the composition of the MOP by recruiting Spo21p and Spo74p (Figure 4B). Taken together, these data suggest that the Mpc54p mutations maintain the composition and the ultrastructure of the MOP complex.


Vesicle docking to the spindle pole body is necessary to recruit the exocyst during membrane formation in Saccharomyces cerevisiae.

Mathieson EM, Suda Y, Nickas M, Snydsman B, Davis TN, Muller EG, Neiman AM - Mol. Biol. Cell (2010)

Mpc54p plays a role in vesicle docking. Representative examples of TEM images of the MOP in single sections of meiosis II spindle pole bodies. Vesicles flush against the surface of the MOP are indicated with a red arrow. Loosely tethered vesicles are indicated with a blue arrow. Electron-dense projections between the MOP and tethered vesicles are indicated with a yellow arrow. Scale bars for whole cell images, 500 nm. Scale bars for higher magnification images, 100 nm.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2965686&req=5

Figure 6: Mpc54p plays a role in vesicle docking. Representative examples of TEM images of the MOP in single sections of meiosis II spindle pole bodies. Vesicles flush against the surface of the MOP are indicated with a red arrow. Loosely tethered vesicles are indicated with a blue arrow. Electron-dense projections between the MOP and tethered vesicles are indicated with a yellow arrow. Scale bars for whole cell images, 500 nm. Scale bars for higher magnification images, 100 nm.
Mentions: The fluorescence data suggested that the composition of the MOP was not disrupted by the mpc54 point mutations (Figure 4B). To examine this possibility more closely, thin-section TEM analysis was used to analyze the structure of the MOP as well as the stages of prospore membrane formation in fine detail. Analysis of cells expressing the mpc54 mutants revealed that the MOPs displayed the distinct, layered morphology of wild-type MOPs (Figure 6). This clearly defined MOP structure was absent in the mpc54Δ mutant (Figure 6). These results support the finding that mpc54 mutant alleles maintain the composition of the MOP by recruiting Spo21p and Spo74p (Figure 4B). Taken together, these data suggest that the Mpc54p mutations maintain the composition and the ultrastructure of the MOP complex.

Bottom Line: During meiosis II in Saccharomyces cerevisiae, the cytoplasmic face of the spindle pole body, referred to as the meiosis II outer plaque (MOP), is modified in both composition and structure to become the initiation site for de novo formation of a membrane called the prospore membrane.The N-termini of two proteins, Mpc54p and Spo21p, were oriented toward the outer surface of the structure.Mutations in the N-terminus of Mpc54p resulted in a unique phenotype: precursor vesicles loosely tethered to the MOP but did not contact its surface.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA.

ABSTRACT
During meiosis II in Saccharomyces cerevisiae, the cytoplasmic face of the spindle pole body, referred to as the meiosis II outer plaque (MOP), is modified in both composition and structure to become the initiation site for de novo formation of a membrane called the prospore membrane. The MOP serves as a docking complex for precursor vesicles that are targeted to its surface. Using fluorescence resonance energy transfer analysis, the orientation of coiled-coil proteins within the MOP has been determined. The N-termini of two proteins, Mpc54p and Spo21p, were oriented toward the outer surface of the structure. Mutations in the N-terminus of Mpc54p resulted in a unique phenotype: precursor vesicles loosely tethered to the MOP but did not contact its surface. Thus, these mpc54 mutants separate the steps of vesicle association and docking. Using these mpc54 mutants, we determined that recruitment of the Rab GTPase Sec4p, as well as the exocyst components Sec3p and Sec8p, to the precursor vesicles requires vesicle docking to the MOP. This suggests that the MOP promotes membrane formation both by localization of precursor vesicles to a particular site and by recruitment of a second tethering complex, the exocyst, that stimulates downstream events of fusion.

Show MeSH
Related in: MedlinePlus