Characterization of SKM1, a Saccharomyces cerevisiae gene encoding a novel Ste20/PAK‐like protein kinase

Martı́n, Humberto; Mendoza, A. Hermoso de; Rodrı́guez-Pachón, José M.; Molina, Marı́a; Nombela, César

doi:10.1046/j.1365-2958.1997.d01-1870.x

Cited by 56 publications

(63 citation statements)

References 53 publications

(70 reference statements)

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“…MATa and MATa strains carrying the wild-type or the itc1 : : kanMX4 alleles of ITC1 were disrupted for STE20 or STE3 genes by the one-step gene disruption technique (Rothstein, 1991), by transformation with the corresponding cassette, ste20 : : URA3 (Martín et al, 1997) or ste3 : : URA3 (kindly donated by G. F. Sprague, Institute of Molecular Biology, University of Oregon, USA). In each case the correct replacement of the gene by the URA3 cassette at the target locus was tested by analytical PCR using genomic DNA of the transformants.…”

Section: Methodsmentioning

confidence: 99%

Cell-type-dependent repression of yeast a-specific genes requires Itc1p, a subunit of the Isw2p–Itc1p chromatin remodelling complex

et al. 2003

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In Saccharomyces cerevisiae MATa haploid cells, the a-specific genes are expressed, whereas in the MATa haploid and MATa/a diploid cell types their transcription is repressed. It is shown in this report that Itc1p, a component of the ATP-dependent Isw2p-Itc1p chromatin remodelling complex, is required for the repression of a-specific genes. It has previously been reported that disruption of the ITC1 gene leads, in MATa cells, to an aberrant cell morphology resembling the polarized mating projection of cells responding to pheromone. The activation of the pheromone signalling pathway in itc1 mutants of both mating types was examined and found to be constitutively active in MATa itc1 but not in MATa itc1 cells. Furthermore, unlike the wild-type, MATa itc1 and MATa/a itc1/itc1 cells secrete a-factor and express significant levels of other a-specific genes. The results indicate that the inappropriate a-factor production in a MATa context, due to the derepression of the a-specific genes, produces an autocrine signalling loop that leads to the aberrant morphology displayed by MATa itc1 cells. It is suggested that the Isw2p-Itc1p complex contributes to maintain the repressive chromatin structure described for the asg operator present in the promoters of a-specific genes.

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Section: Methodsmentioning

confidence: 99%

Cell-type-dependent repression of yeast a-specific genes requires Itc1p, a subunit of the Isw2p–Itc1p chromatin remodelling complex

et al. 2003

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“…Very little is known about Skm1, and its localization has not been reported previously (Martín et al, 1997). Therefore, we first analyzed the localization of full-length Skm1 fused to GFP.…”

Section: Molecular Biology Of the Cell 4828mentioning

confidence: 99%

“…In addition, Cla4 regulates mitotic entry and exit (Hö fken and Schiebel, 2002;Seshan et al, 2002;Sakchaisri et al, 2004). Very little is known about Skm1, and no clear function has been attributed to this PAK (Martín et al, 1997). Interestingly, Ste20 and Cla4 interact with Erg4, Cbr1 and Ncp1, which are all involved in sterol biosynthesis, and the deletion of the corresponding genes results in various polarity defects, suggesting that sterol biosyn- Abbreviations used: BR, basic-rich; CRIB, Cdc42/Rac-interactive binding; PAK, p21-activated kinase; PH, pleckstrin homology; TLC, thin layer chromatography.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, Cla4 regulates mitotic entry and exit (Hö fken and Schiebel, 2002;Seshan et al, 2002;Sakchaisri et al, 2004). Very little is known about Skm1, and no clear function has been attributed to this PAK (Martín et al, 1997). Interestingly, Ste20 and Cla4 interact with Erg4, Cbr1 and Ncp1, which are all involved in sterol biosynthesis, and the deletion of the corresponding genes results in various polarity defects, suggesting that sterol biosynThis article was published online ahead of print in MBC in Press (http://www.molbiolcell.org/cgi/doi/10.1091/mbc.E09 -01-0034) on September 30, 2009. thesis is crucial for cell polarization (Ni and Snyder, 2001;Tiedje et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

“…Consistently, in few cells we observed nuclear localization of wild-type Ste20 ( Figure 3E). However, since Ste20 was only weakly enriched in the nucleus compared with the surrounding cytoplasm, the number of cells with a nuclear Ste20 signal was difficult to quantify.Very little is known about Skm1, and its localization has not been reported previously (Martín et al, 1997). Therefore, we first analyzed the localization of full-length Skm1 fused to GFP.…”

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The Cdc42 Effectors Ste20, Cla4, and Skm1 Down-Regulate the Expression of Genes Involved in Sterol Uptake by a Mitogen-activated Protein Kinase-independent Pathway

Lin

Unden

Jacquier

et al. 2009

MBoC

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In Saccharomyces cerevisiae, the Rho-type GTPase Cdc42 regulates polarized growth through its effectors, including the p21-activated kinases (PAKs) Ste20, Cla4, and Skm1. Previously, we demonstrated that Ste20 interacts with several proteins involved in sterol synthesis that are crucial for cell polarization. Under anaerobic conditions, sterols cannot be synthesized and need to be imported into cells. Here, we show that Ste20, Cla4, and Skm1 form a complex with Sut1, a transcriptional regulator that promotes sterol uptake. All three PAKs can translocate into the nucleus and down-regulate the expression of genes involved in sterol uptake, including the Sut1 targets AUS1 and DAN1 by a novel mechanism. Consistently, deletion of either STE20, CLA4, or SKM1 results in an increased sterol influx and PAK overexpression inhibits sterol uptake. For Ste20, we demonstrate that the down-regulation of gene expression requires nuclear localization and kinase activity of Ste20. Furthermore, the Ste20-mediated control of expression of sterol uptake genes depends on SUT1 but is independent of a mitogen-activated protein kinase signaling cascade. Together, these observations suggest that PAKs translocate into the nucleus, where they modulate expression of sterol uptake genes via Sut1, thereby controlling sterol homeostasis. INTRODUCTIONThe small Rho GTPase Cdc42 plays a central role in the regulation of cellular polarity in eukaryotic cells (EtienneManneville, 2004;Jaffe and Hall, 2005). In the budding yeast Saccharomyces cerevisiae, Cdc42 regulates different types of polarized growth during various phases of its life cycle, including budding during vegetative growth, mating between haploid cells of opposite mating types, and filamentous growth upon nutrient limitation (Park and Bi, 2007). Cdc42 promotes polarized growth through multiple pathways, including polarization of the actin cytoskeleton and directed vesicle trafficking. Among the Cdc42 effectors that trigger these pathways are Ste20, Cla4 and Skm1, members of the p21-activated kinase (PAK) family of serine/threonine protein kinases (Hofmann et al., 2004;Park and Bi, 2007).Cdc42 recruits Ste20 and Cla4 from the cytoplasm and activates them at the plasma membrane at sites of polarized growth. Therefore, Ste20 and Cla4 are enriched at tips of buds and mating projections (Peter et al., 1996;Leberer et al., 1997;Holly and Blumer, 1999). The recruitment of Ste20 and Cla4 to these sites is governed by protein-protein as well as protein-lipid interactions. PAKs carry a conserved Cdc42/ Rac-interactive binding (CRIB) domain that mediates binding to Cdc42 and regulates their activity (Cvrckova et al., 1995;Peter et al., 1996;Leberer et al., 1997;Lamson et al., 2002;Ash et al., 2003). Ste20 and Cla4 also bind to Bem1, a scaffold protein that brings Cdc42, its activator Cdc24 and either Ste20 or Cla4, into proximity (Leeuw et al., 1998;Gulli et al., 2000;Bose et al., 2001;Yamaguchi et al., 2007). In addition, phosphoinositide-binding domains promote the association with membrane lip...

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Candida glabrata Ste20 is involved in maintaining cell wall integrity and adaptation to hypertonic stress, and is required for wild‐type levels of virulence

Calcagno

Bignell

Rogers

et al. 2004

Yeast

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The conserved family of fungal Ste20 p21-activated serine-threonine protein kinases regulate several signalling cascades. In Saccharomyces cerevisiae Ste20 is involved in pheromone signalling, invasive growth, the hypertonic stress response, cell wall integrity and binds Cdc42, a Rho-like small GTP-binding protein required for polarized morphogenesis. We have cloned the STE20 homologue from the fungal pathogen Candida glabrata and have shown that it is present in a single copy in the genome. Translation of the nucleotide sequence predicts that C. glabrata Ste20 contains a highly conserved p21-activated serine-threonine protein kinase domain, a binding site for G-protein β subunits and a regulatory Rho-binding domain that enables the kinase to interact with Cdc42 and/or Rho-like small GTPases. C. glabrata Ste20 has 53% identity and 58% predicted amino acid similarity to S. cerevisiae Ste20 and can complement both the nitrogen starvation-induced filamentation and mating defects of S. cerevisiae ste20 mutants. Analysis of ste20 null and disrupted strains suggest that in C. glabrata Ste20 is required for a fully functional hypertonic stress response and intact cell wall integrity pathway. C. glabrata Ste20 is not required for nitrogen starvation-induced filamentation. Survival analysis revealed that C. glabrata ste20 mutants, while still able to cause disease, are mildly attenuated for virulence compared to reconstituted STE20 cells.

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**Characterization of SKM1, a Saccharomyces cerevisiae gene encoding a novel Ste20/PAK‐like protein kinase**

Cited by 56 publications

References 53 publications

Cell-type-dependent repression of yeast a-specific genes requires Itc1p, a subunit of the Isw2p–Itc1p chromatin remodelling complex

Cell-type-dependent repression of yeast a-specific genes requires Itc1p, a subunit of the Isw2p–Itc1p chromatin remodelling complex

The Cdc42 Effectors Ste20, Cla4, and Skm1 Down-Regulate the Expression of Genes Involved in Sterol Uptake by a Mitogen-activated Protein Kinase-independent Pathway

Candida glabrata Ste20 is involved in maintaining cell wall integrity and adaptation to hypertonic stress, and is required for wild‐type levels of virulence

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