The<i>Schizosaccharomyces pombe</i>Syntaxin 1 Homolog, Psy1, Is Essential in the Development of the Forespore Membrane

Maeda, Yukari; Kashiwazaki, Jun; Shimoda, Chikashi; Nakamura, Taro

doi:10.1271/bbb.80575

Cited by 27 publications

(37 citation statements)

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“…The present study, together with our previous work (6,7,40), shows that all of the fission yeast PM SNARE components play a critical role in sporulation. Unlike S. cerevisiae, S. pombe has a sole gene encoding each of the PM SNARE components.…”

Section: Discussionsupporting

confidence: 79%

“…As a result, it has been suggested that spore wall materials are transported by secretory vesicles. Because the sporulation-deficient sec9-10 and psy1-S1 mutant cells form no spores, possibly due to severe defects in FSM formation, we could not examine whether the PM SNAREs are indeed required for spore wall formation (7,40). Compared with sec9-10 and psy1-S1, syb1-S1 exhibited a milder phenotype, and most of the syb1-S1 spores germinated.…”

Section: Discussionmentioning

confidence: 99%

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The Fission Yeast Synaptobrevin Ortholog Syb1 Plays an Important Role in Forespore Membrane Formation and Spore Maturation

et al. 2013

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Synaptobrevin, also called vesicle-associated membrane protein (VAMP), is a component of the plasma membrane N-methylmaleimide-sensitive factor attachment protein receptor (SNARE) complex, which plays a key role in intracellular membrane fusion. Previous studies have revealed that, similar to synaptobrevin in other organisms, the fission yeast synaptobrevin ortholog Syb1 associates with post-Golgi secretory vesicles and is essential for cytokinesis and cell elongation. Here, we report that Syb1 has a role in sporulation. After nitrogen starvation, green fluorescent protein (GFP)-Syb1 is found in intracellular dots. As meiosis proceeds, GFP-Syb1 accumulates around the nucleus and then localizes at the forespore membrane (FSM). We isolated a syb-S1 mutant, which exhibits a defect in sporulation. In syb1-S1 mutants, the FSM begins to form but fails to develop a normal morphology. Electron microscopy shows that an abnormal spore wall is often formed in syb1-S1 mutant spores. Although most syb1-S1 mutant spores are germinated, they are less tolerant to ethanol than wild-type spores. The syb1-S1 allele carries a missense mutation, resulting in replacement of a conserved cysteine residue adjacent to the transmembrane domain, which reduces the stability and abundance of the Syb1 protein. Taken together, these results indicate that Syb1 plays an important role in both FSM assembly and spore wall formation. Members of the soluble N-methylmaleimide-sensitive factor attachment protein receptor (SNARE) family contribute to transport specificity by regulating interactions between membrane vesicles and their appropriate target membranes (1). SNARE proteins exist as complementary sets of v-SNAREs, found on vesicle membranes, and t-SNAREs, found on target membranes. Recent classification, however, takes into account the structural features of SNARE proteins, subdividing them into RSNAREs and Q-SNAREs (2).There are approximately 40 SNAREs in an animal cell, and each associates with a particular organelle in the biosyntheticsecretory or endocytic pathway (3). A v-SNARE is a single polypeptide chain, whereas a t-SNARE complex is composed of two or three proteins. The v-SNAREs and t-SNAREs have characteristic helical domains, and when a v-SNARE interacts with a t-SNARE, the helical domains of one wrap around the helical domains of the other to form a stable four-helix bundle. The resulting trans-SNARE complex locks the two membranes together.SNAREs have been well characterized in neurons, where they mediate the docking and fusion of synaptic vesicles at the nerve terminal's plasma membrane (PM) during the process of neurotransmitter release. The SNARE complex responsible for docking synaptic vesicles at the PM of nerve terminals consists of three proteins. The transmembrane proteins v-SNARE synaptobrevin (also called vesicle-associated membrane protein [VAMP]) and t-SNARE syntaxin each contribute one ␣-helix to the complex (4, 5), whereas the peripheral membrane protein t-SNARE SNAP-25 contributes two ␣-helices to the four-helix bun...

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Section: Discussionsupporting

confidence: 79%

Section: Discussionmentioning

confidence: 99%

The Fission Yeast Synaptobrevin Ortholog Syb1 Plays an Important Role in Forespore Membrane Formation and Spore Maturation

et al. 2013

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“…Psy1 is a plasma membrane-resident t-SNARE protein that is homologous to budding yeast Sso1 and Sso2 (1) and human syntaxin-1 (2). The gfp-psy1 fusion gene was integrated at the ade6 locus on chromosome III (14).…”

Section: Methodsmentioning

confidence: 99%

Schizosaccharomyces pombe Calmodulin, Cam1, Plays a Crucial Role in Sporulation by Recruiting and Stabilizing the Spindle Pole Body Components Responsible for Assembly of the Forespore Membrane

et al. 2010

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Calmodulin in Schizosaccharomyces pombe is encoded by the cam1؉ gene, which is indispensable for both vegetative growth and sporulation. Here, we report how Cam1 functions in spore formation. We found that Cam1 preferentially localized to the spindle pole body (SPB) during meiosis and sporulation. Formation of the forespore membrane, a precursor of the plasma membrane in spores, was blocked in a missense cam1 mutant, which was viable but unable to sporulate. Three SPB proteins necessary for the onset of forespore membrane formation, Spo2, Spo13, and Spo15, were unable to localize to the SPB in the cam1 mutant although five core SPB components that were tested were present. Recruitment of Spo2 and Spo13 is known to require the presence of Spo15 in the SPB. Notably, Spo15 was unstable in the cam1 mutant, and as a result, SPB localization of Spo2 and Spo13 was lost. Overexpression of Spo15 partially alleviated the sporulation defect in the cam1 mutant. These results indicate that calmodulin plays an essential role in forespore membrane formation by stably maintaining Spo15, and thus Spo2 and Spo13, at the SPB in meiotic cells.

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“…A candidate could be the forespore membrane, which is a precursor of the spore plasma membrane that surrounds nuclei during MII 24 . The forespore membrane was visualized with the GFPtagged tSNARE protein Psy1/Syntaxin 1 (GFPPsy1) 25 . As reported previously 26 , the forespore membrane started to assemble around the SPBs in a crescent shape after they were separated by ipMTs (15 min; Fig.…”

Section: Normal Chromosome Segregation In Absence Of Ipmts In MIImentioning

confidence: 99%

Interpolar microtubules are dispensable in fission yeast meiosis II

2012

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The mitotic spindle consists of two types of microtubules. Dynamic kinetochore microtubules capture kinetochores, whereas stable interpolar microtubules serve as the structural backbone that connects the two spindle poles. Both have been believed to be indispensable for cell division in eukaryotes. Here we demonstrate that interpolar microtubules are dispensable for the second division of meiosis in fission yeast. Even when interpolar microtubules are disrupted by a microtubule-depolymerizing drug, spindle poles separate and chromosomes segregate poleward in second division of meiosis in most zygotes, producing viable spores. The forespore membrane, which encapsulates the nucleus in second division of meiosis and is guided by septins and the leading-edge proteins, is responsible for carrying out meiotic events in the absence of interpolar microtubules. Furthermore, during physiological second division of meiosis without microtubule perturbation, the forespore membrane assembly contributes structurally to spindle pole separation and nuclear division, generating sufficient force for spindle pole separation and subsequent events independently of interpolar microtubules.

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TheSchizosaccharomyces pombeSyntaxin 1 Homolog, Psy1, Is Essential in the Development of the Forespore Membrane

Cited by 27 publications

References 1 publication

The Fission Yeast Synaptobrevin Ortholog Syb1 Plays an Important Role in Forespore Membrane Formation and Spore Maturation

The Fission Yeast Synaptobrevin Ortholog Syb1 Plays an Important Role in Forespore Membrane Formation and Spore Maturation

Schizosaccharomyces pombe Calmodulin, Cam1, Plays a Crucial Role in Sporulation by Recruiting and Stabilizing the Spindle Pole Body Components Responsible for Assembly of the Forespore Membrane

Interpolar microtubules are dispensable in fission yeast meiosis II

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