A Role for the Septation Initiation Network in Septum Assembly Revealed by Genetic Analysis of <i>sid2-250</i> Suppressors

Jin, Quan‐wen; Zhou, Mian; Bimbó, Andrea; Balasubramanian, Mohan K.; McCollum, Dannel

doi:10.1534/genetics.105.050955

Cited by 47 publications

(62 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Overexpression of Rho1 partially rescues lethality of Sid2 mutants at low restrictive temperature (Jin et al 2006). Interestingly, we observed that moderate overexpression of Rho1 under the nmt41x promoter in a plasmid (p41rho1) efficiently suppressed lethality of etd1D mutants ( Figure 1C), suggesting that Etd1, as proposed for Sid2 (Jin et al 2006), functions in downstream activation of Rho1.…”

Section: Resultsmentioning

confidence: 65%

“…In addition, Etd1 localization to the medial ring requires Sid2-Mob1 activity (Daga et al 2005). Thus, we further analyzed whether Etd1 is involved in connecting Sid2-mediated SIN signaling with activation of Rho1 and the cell-wall synthesis machinery.Overexpression of Rho1 partially rescues lethality of Sid2 mutants at low restrictive temperature (Jin et al 2006). Interestingly, we observed that moderate overexpression of Rho1 under the nmt41x promoter in a plasmid (p41rho1) efficiently suppressed lethality of etd1D mutants ( Figure 1C), suggesting that Etd1, as proposed for Sid2 (Jin et al 2006), functions in downstream activation of Rho1.…”

mentioning

confidence: 65%

“…The SIN is thought to regulate Rho1 during cytokinesis. Accordingly, SIN-deficient cells fail to produce a septum and undergo lysis as a terminal phenotype (Jin et al 2006). Little is known about the mechanisms that link the SIN pathway with Rho1 and the cell-wall synthesis activity, but the SIN regulator Etd1 could play a role in this link (Daga et al 2005).…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Feedback Regulation of SIN by Etd1 and Rho1 in Fission Yeast

et al. 2014

View full text Add to dashboard Cite

In fission yeast, the septation initiation network (SIN) is thought to promote cytokinesis by downstream activation of Rho1, a conserved GTPase that controls cell growth and division. Here we show that Etd1 and PP2A-Pab1, antagonistic regulators of SIN, are Rho1 regulators. Our genetic and biochemical studies indicate that a C-terminal region of Etd1 may activate Rho1 by directly binding it, whereas an N-terminal domain confers its ability to localize at the growing tips and the division site where Rho1 functions. In opposition to Etd1, our results indicate that PP2A-Pab1 inhibits Rho1. The SIN cascade is upstream-regulated by the Spg1 GTPase. In the absence of Etd1, activity of Spg1 drops down prematurely, thereby inactivating SIN. Interestingly, we find that ectopic activation of Rho1 restores Spg1 activity in Etd1-depleted cells. By using a cytokinesis block strategy, we show that Rho1 is essential to feedbackactivate Spg1 during actomyosin ring constriction. Therefore, activation of Spg1 by Rho1, which in turn is regulated by Etd1, uncovers a novel feedback loop mechanism that ensures SIN activity while cytokinesis is progressing.F ISSION yeast cells grow by elongating at their cell ends before dividing by forming a medially placed division septum during cytokinesis. New-born cells initiate growth in a monopolar manner from the old cell end that existed before division. During G2, cells initiate growth from the new end in a process known as NETO (new end take-off). These cells then grow in a bipolar mode until mitosis, when they stop growth and initiate cell division by septation (Mitchison and Nurse 1985;Hayles and Nurse 2001). Both polar growth and septation require proper cell membrane and cell-wall synthesis to ensure cell integrity. In Schizosaccharomyces pombe, the cell wall is composed of b-glucan, a-glucan, and mannoproteins. Synthesis of the major cell wall and primary septum polymer, 1,3-b-glucan, requires the activity of Drc1/Cps1/Bgs1 1,3-b-glucan synthase, which in turn is regulated by the guanosine triphosphate (GTP)-binding protein Rho1 (Garcia et al. 2006;Cortes et al. 2007). As with all GTPases, Rho1 acts as a binary switch, cycling between inactive GDP-bound and active GTPbound conformational states (Yang et al. 2003). This transition is controlled by three types of proteins: GEFs (guanine exchange factors), which catalyze the exchange of GDP for GTP, rendering the protein active; GAPs (GTPase activating proteins), which enhance nucleotide hydrolysis, inactivating the GTPase; and guanine nucleotide dissociation inhibitors, which appear to block spontaneous activation (Garcia et al. 2006).Upon the onset of mitosis, growth ceases at the cell ends and is re-established in the middle of the cell, where the actomyosin ring forms. At the end of mitosis, once the two sets of chromosomes have segregated, actomyosin ring constriction and septum formation is triggered by the septation initiation network (SIN) from the spindle pole body (SPB) (Krapp et al. 2004;Wolfe and Gould 2005). The nucl...

show abstract

Section: Resultsmentioning

confidence: 65%

mentioning

confidence: 65%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Feedback Regulation of SIN by Etd1 and Rho1 in Fission Yeast

et al. 2014

View full text Add to dashboard Cite

show abstract

“…The double null mutant is viable, but is sensitive to temperature (high and low) and stress and shows defects in septation and cleavage ( Jiang and Hallberg 2000;Tanabe et al 2001). Curiously, a mutation in the regulatory subunit B9 Par1 is able to suppress the septation defects of cdc11-136, cdc7-24, spg1-B8 (Le Goff et al 2001), and sid2-250 mutants ( Jin et al 2006).…”

Section: Resultsmentioning

confidence: 99%

Antagonistic Roles of PP2A-Pab1 and Etd1 in the Control of Cytokinesis in Fission Yeast

et al. 2010

View full text Add to dashboard Cite

In Schizosaccharomyces pombe, Etd1 is a positive regulator of the septation initiation network (SIN), a conserved GTPase-regulated kinase cascade that triggers cytokinesis. Here we show that a mutation in the pab1 gene, which encodes the B-regulatory subunit of the protein phosphatase 2A (PP2A), suppresses mutations in the etd1 gene. Etd1 is required for the function of the GTPase Spg1, a key regulator of SIN signaling. Interestingly, the loss of Pab1 function restored the activity of Spg1 in Etd1-deficient cells. This result suggests that PP2A-Pab1-mediated dephosphorylation inhibits Spg1, thus antagonizing Etd1 function. The loss of pab1 function also rescues the lethality of mutants of other genes in the SIN cascade such as mob1, sid1, and cdc11. Two-hybrid assays indicate that Pab1 physically interacts with Mob1, Sid1, Sid2, and Cdc11, suggesting that the phosphatase 2A B-subunit is a component of the SIN complex. Together, our results indicate that PP2A-Pab1 plays a novel role in cytokinesis, regulating SIN activity at different levels. Pab1 is also required to activate polarized cell growth. Thus, PP2A-Pab1 may be involved in coordinating polar growth and cytokinesis.

show abstract

“…Sid2p interacts with Mob1p and this interaction is required both for localisation of Sid2p to a medial ring where the septum will form and for Sid2p catalytic activity (Hou et al, 2004). Sid2p may promote septum formation by activating the S. pombe homologue of Ace2p, but the precise mechanism of how it does this remains unclear (Jin et al, 2006). A Cdc15-related kinase, Cdc7p, is also required for septum formation; however direct activation of Sid2p by Cdc7p has not been demonstrated (Mehta and Gould, 2006).…”

Section: Ndr Kinasesmentioning

confidence: 99%

Regulation of polarised growth in fungi

Sudbery

2008

Fungal Biology Reviews

View full text Add to dashboard Cite

Polarised growth in fungi occurs through the delivery of secretory vesicles along tracks formed by cytoskeletal elements to specific sites on the cell surface where they dock with a multiprotein structure called the exocyst before fusing with the plasmamembrane. The budding yeast, Saccharomyces cerevisiae has provided a useful model to investigate the mechanisms involved and their control. Cortical markers, provided by bud site selection pathways during budding, the septin ring during cytokinesis or the stimulation of the pheromone response receptors during mating, act through upstream signalling pathways to localise Cdc24, the GEF for the rho family GTPase, Cdc42. Cdc42 in its GTP-bound activates a multiprotein protein complex called the polarisome which nucleates actin cables along which the secretory vesicles are transported to the cell surface. Hyphae can elongate at a rate orders of magnitude faster than the extension of a yeast bud, so understanding hyphal growth will require substantial modification of the yeast paradigm.The rapid rate of hyphal growth is driven by a structure called the Spitzenkörper, located just behind the growing tip and which is rich in secretory vesicles. It is thought that secretory vesicles are delivered to the apical region where they accumulate in the Spitzenkörper. The Spitzenkörper then acts as vesicle supply centre in which vesicles exit the Spitzenkörper in all directions, but because of its proximity, the tip receives a greater concentration of vesicles per unit area than subapical regions. There are no obvious equivalents to the bud site selection pathway to provide a spatial landmark for polarised growth in hyphae. However, an emerging model is the way that the site of polarised growth in the fission yeast, Schizosaccharomyces pombe, is marked by delivery of the kelch repeat protein, Tea1, along microtubules. The relationship of the Spitzenkörper to the polarisome and the mechanisms that promote its formation are key questions that form the focus of current research.3

show abstract

A Role for the Septation Initiation Network in Septum Assembly Revealed by Genetic Analysis of sid2-250 Suppressors

Cited by 47 publications

References 57 publications

Feedback Regulation of SIN by Etd1 and Rho1 in Fission Yeast

Feedback Regulation of SIN by Etd1 and Rho1 in Fission Yeast

Antagonistic Roles of PP2A-Pab1 and Etd1 in the Control of Cytokinesis in Fission Yeast

Regulation of polarised growth in fungi

Contact Info

Product

Resources

About