Activation of the Smk1 Mitogen-Activated Protein Kinase by Developmentally Regulated Autophosphorylation

Whinston, Elizabeth Rogers; Omerza, Gregory; Singh, Amrita; Tio, Chong Wai; Winter, Edward

doi:10.1128/mcb.00973-12

Cited by 23 publications

(48 citation statements)

References 68 publications

(111 reference statements)

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“…Since Sps1 is a serine/threonine kinase and is in complex with Ssp1, we tested whether SPS1 is required for Ssp1 phosphorylation. We assayed the 10-hr samples from Figure 8C for phosphorylation using a Phos-tag gel, which specifically retards the migration of phosphoproteins through the matrix, allowing resolution of multiple phosphorylation states (Kinoshita et al 2006;Whinston et al 2013). In WT cells, the Ssp1-13x-myc fusion protein migrates as several distinct bands on a Phos-tag gel, consistent with Ssp1 having multiple phosphorylation sites ( Figure 8H).…”

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Timely Closure of the Prospore Membrane Requires SPS1 and SPO77 in Saccharomyces cerevisiae

et al. 2016

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During sporulation in Saccharomyces cerevisiae, a double lipid bilayer called the prospore membrane is formed de novo, growing around each meiotic nucleus and ultimately closing to create four new cells within the mother cell. Here we show that SPS1, which encodes a kinase belonging to the germinal center kinase III family, is involved in prospore membrane development and is required for prospore membrane closure. We find that SPS1 genetically interacts with SPO77 and see that loss of either gene disrupts prospore membrane closure in a similar fashion. Specifically, cells lacking SPS1 and SPO77 produce hyperelongated prospore membranes from which the leading edge protein complex is not removed from the prospore membrane in a timely fashion. The SPS1/ SPO77 pathway is required for the proper phosphorylation and stability of Ssp1, a member of the leading edge protein complex that is removed and degraded when the prospore membrane closes. Genetic dissection of prospore membrane closure finds SPS1 and SPO77 act in parallel to a previously described pathway of prospore membrane closure that involves AMA1, an activator of the meiotic anaphase promoting complex.KEYWORDS prospore membrane; meiotic exit; anaphase promoting complex; sporulation; cytokinesis; germinal center kinase B IOLOGICAL membranes provide a barrier for inhibiting the flow of materials between a cell and its surroundings and for compartmentalizing the contents of the various organelles within a cell. The size and shape of membranes are central to their functions. Membranes are essential for many fundamental cellular processes including ion balance, energy generation, and secretion. In cell division, membrane dynamics are particularly important, where they act to segregate the contents of the cellular progeny.The process of cell division differs among cells. Most commonly, animal cells divide through a mechanism requiring the assembly of an actin-based contractile ring at the division site (reviewed in Green et al. 2012). This actomyosin ring contracts and matures, ultimately leading to scission of the membrane necks mediated by the ESCRTIII (endosomal sorting complex required for transport III) complex. However, other variations of cytokinesis occur: cellularization during early Drosophila embryogenesis, which requires the growth of membranes around the nuclei before the contractile event (Lee and Harris 2014) and cell division in plants, which requires the secretion of vesicles to the division plane to form the phragmoplast, which will eventually separate the two daughter cells (reviewed in Jürgens 2005). Actin is not always involved in cytokinesis; although prokaryotic cells have actin-like filaments (reviewed in Carballido-López 2006), these filaments are not used for cytokinesis (Pollard and Wu 2010). Similarly, cytokinesis in Trypanosoma brucei (a bikont eukaryote) does not require actin but seems to utilize microtubules (Wheeler et al. 2013). In the budding yeast Saccharomyces cerevisiae, an actin-based contractile ring plays a role in ...

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confidence: 93%

“…Phos-Tag gels were made using Phos-tag acrylamide AAL-107 (WACO) at a final concentration of 31.4 mM Phos-tag and 50.6 mM MnCl 2 in an otherwise standard SDS-polyacrylamide gel, as in Whinston et al (2013). Samples were prepared as above and run at 80 V at 4°before being transferred and imaged, as above.…”

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confidence: 99%

Timely Closure of the Prospore Membrane Requires SPS1 and SPO77 in Saccharomyces cerevisiae

et al. 2016

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“…Genotype/phenotype studies show that an smk1 phosphosite mutant encoding a Y209F change (smk1-Y209F mutant) has a partial-function terminal phenotype (10). The phenotype of the ssp2Δ mutant is more severe than that of the smk1-Y209F mutant and similar to that of the smk1Δ mutant.…”

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confidence: 94%

“…SMK1 mRNA is translated shortly after it is transcribed, and the newly translated Smk1 protein is phosphorylated on T207 by Cak1 (8,10). In contrast, SSP2 mRNA is translationally repressed until MII, as nuclear segregation is being completed.…”

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Ssp2 Binding Activates the Smk1 Mitogen-Activated Protein Kinase

Tio

Omerza

Phillips

et al. 2017

Molecular and Cellular Biology

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Smk1 is a meiosis-specific mitogen-activated protein kinase (MAPK) in Saccharomyces cerevisiae that couples spore morphogenesis to the completion of chromosome segregation. Similar to other MAPKs, Smk1 is controlled by phosphorylation of a threonine (T) and a tyrosine (Y) in its activation loop. However, it is not activated by a dual-specificity MAPK kinase. Instead, T207 in Smk1's activation loop is phosphorylated by the cyclin-dependent kinase (CDK)-activating kinase (Cak1), and Y209 is autophosphorylated in an intramolecular reaction that requires the meiosis-specific protein Ssp2. In this study, we show that Smk1 is catalytically inert unless it is bound by Ssp2. While Ssp2 binding activates Smk1 by a mechanism that is independent of activation loop phosphorylation, binding also triggers autophosphorylation of Y209 in Smk1, which, along with Cak1-mediated phosphorylation of T207, further activates the kinase. Autophosphorylation of Smk1 on Y209 also appears to modify the specificity of the MAPK by suppressing Y kinase and enhancing S/T kinase activity. We also found that the phosphoconsensus motif preference of Ssp2/Smk1 is more extensive than that of other characterized MAPKs. This study therefore defines a novel mechanism of MAPK activation requiring binding of an activator and also shows that MAPKs can be diversified to recognize unique phosphorylation motifs.

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The MAPK homolog, Smk1, promotes assembly of the glucan layer of the spore wall in S. cerevisiae

Lee‐Soety,

Resch,

Rimal

et al. 2024

Yeast

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Smk1 is a MAPK homolog in the yeast Saccharomyces cerevisiae that controls the postmeiotic program of spore wall assembly. During this program, haploid cells are surrounded by a layer of mannan and then a layer of glucan. These inner layers of the spore wall resemble the vegetative cell wall. Next, the outer layers consisting of chitin/chitosan and then dityrosine are assembled. The outer layers are spore‐specific and provide protection against environmental stressors. Smk1 is required for the proper assembly of spore walls. However, the protective properties of the outer layers have limited our understanding of how Smk1 controls this morphogenetic program. Mutants lacking the chitin deacetylases, Cda1 and Cda2, form spores that lack the outer layers of the spore wall. In this study, cda1,2∆ cells were used to demonstrate that Smk1 promotes deposition of the glucan layer of the spore wall through the partially redundant glucan synthases Gsc2 and Fks3. Although Gsc2 is localized to sites of spore wall assembly in the wild type, it is mislocalized in the mother cell cytoplasm in the smk1∆ mutant. These findings suggest that Smk1 controls assembly of the spore wall by regulating the localization of Gsc2 during sporogenesis.

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Activation of the Smk1 Mitogen-Activated Protein Kinase by Developmentally Regulated Autophosphorylation

Cited by 23 publications

References 68 publications

Timely Closure of the Prospore Membrane Requires SPS1 and SPO77 in Saccharomyces cerevisiae

Timely Closure of the Prospore Membrane Requires SPS1 and SPO77 in Saccharomyces cerevisiae

Ssp2 Binding Activates the Smk1 Mitogen-Activated Protein Kinase

The MAPK homolog, Smk1, promotes assembly of the glucan layer of the spore wall in S. cerevisiae

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