Limits...
The high osmolarity glycerol response (HOG) MAP kinase pathway controls localization of a yeast golgi glycosyltransferase.

Reynolds TB, Hopkins BD, Lyons MR, Graham TR - J. Cell Biol. (1998)

Bottom Line: Biol.We have found that basal signaling through the HOG pathway is required to localize Mnn1-s to the Golgi in standard osmotic conditions.Mutations in HOG1 and LDR1 also perturb localization of intact Mnn1p, resulting in its loss from early Golgi compartments and a concomitant increase of Mnn1p in later Golgi compartments.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology, Vanderbilt University, Nashville, Tennessee 37235, USA.

ABSTRACT
The yeast alpha-1,3-mannosyltransferase (Mnn1p) is localized to the Golgi by independent transmembrane and lumenal domain signals. The lumenal domain is localized to the Golgi complex when expressed as a soluble form (Mnn1-s) by exchange of its transmembrane domain for a cleavable signal sequence (Graham, T. R., and V. A. Krasnov. 1995. Mol. Biol. Cell. 6:809-824). Mutants that failed to retain the lumenal domain in the Golgi complex, called lumenal domain retention (ldr) mutants, were isolated by screening mutagenized yeast colonies for those that secreted Mnn1-s. Two genes were identified by this screen, HOG1, a gene encoding a mitogen-activated protein kinase (MAPK) that functions in the high osmolarity glycerol (HOG) pathway, and LDR1. We have found that basal signaling through the HOG pathway is required to localize Mnn1-s to the Golgi in standard osmotic conditions. Mutations in HOG1 and LDR1 also perturb localization of intact Mnn1p, resulting in its loss from early Golgi compartments and a concomitant increase of Mnn1p in later Golgi compartments.

Show MeSH

Related in: MedlinePlus

Model for the potential role of the HOG and PKC-MPK pathways in regulating cell wall biosynthesis. The HOG  pathway is required for Golgi localization of Mnn1-s, controls the  distribution of Mnn1p between early and late Golgi compartments, and upregulates the activity of an exoglucanase, possibly  in response to excess rigidity in the cell wall. Conversely, the  PKC-MPK pathway is thought to sense a weakened cell wall and  respond by upregulating the transcription of cell wall biosynthetic  enzymes. See Discussion for additional details.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2132948&req=5

Figure 8: Model for the potential role of the HOG and PKC-MPK pathways in regulating cell wall biosynthesis. The HOG pathway is required for Golgi localization of Mnn1-s, controls the distribution of Mnn1p between early and late Golgi compartments, and upregulates the activity of an exoglucanase, possibly in response to excess rigidity in the cell wall. Conversely, the PKC-MPK pathway is thought to sense a weakened cell wall and respond by upregulating the transcription of cell wall biosynthetic enzymes. See Discussion for additional details.

Mentions: The HOG1 gene encodes a well-characterized member of the MAPK family involved in the high osmolarity glycerol response (HOG) pathway (diagrammed in Fig. 8), a signal transduction cascade that responds to increases in extracellular osmolarity. Hog1p is activated through two redundant signal transduction pathways. The Sln1p-Ypd1p histidine kinase phosphorelay osmosensor complex actively represses Ssk1p through phosphorylation in normal osmotic conditions. In the presence of hyperosmotic stress the Sln1p-Ypd1p osmosensor complex becomes inactive. This relieves repression of Ssk1p, which in turn activates the HOG pathway through phosphorylation of the redundant MAPK kinase kinases (MAPKKKs) Ssk2p and Ssk22p. These MAPKKKs activate the MAPK kinase (MAPKK) Pbs2p, which then activates Hog1p through phosphorylation. Activated Hog1p in turn upregulates the transcription of osmotic stress response genes such as GPD1, which encodes glycerol-3-phosphate dehydrogenase and HSP12, which encodes one of the major small heat shock proteins in yeast. Alternatively, a second input into this pathway, the Sho1p osmosensor, activates the Ste11p MAPKKK, which in turn activates the Pbs2p MAPKK, which activates Hog1p (Wurgler-Murphy and Saito, 1997).


The high osmolarity glycerol response (HOG) MAP kinase pathway controls localization of a yeast golgi glycosyltransferase.

Reynolds TB, Hopkins BD, Lyons MR, Graham TR - J. Cell Biol. (1998)

Model for the potential role of the HOG and PKC-MPK pathways in regulating cell wall biosynthesis. The HOG  pathway is required for Golgi localization of Mnn1-s, controls the  distribution of Mnn1p between early and late Golgi compartments, and upregulates the activity of an exoglucanase, possibly  in response to excess rigidity in the cell wall. Conversely, the  PKC-MPK pathway is thought to sense a weakened cell wall and  respond by upregulating the transcription of cell wall biosynthetic  enzymes. See Discussion for additional details.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2132948&req=5

Figure 8: Model for the potential role of the HOG and PKC-MPK pathways in regulating cell wall biosynthesis. The HOG pathway is required for Golgi localization of Mnn1-s, controls the distribution of Mnn1p between early and late Golgi compartments, and upregulates the activity of an exoglucanase, possibly in response to excess rigidity in the cell wall. Conversely, the PKC-MPK pathway is thought to sense a weakened cell wall and respond by upregulating the transcription of cell wall biosynthetic enzymes. See Discussion for additional details.
Mentions: The HOG1 gene encodes a well-characterized member of the MAPK family involved in the high osmolarity glycerol response (HOG) pathway (diagrammed in Fig. 8), a signal transduction cascade that responds to increases in extracellular osmolarity. Hog1p is activated through two redundant signal transduction pathways. The Sln1p-Ypd1p histidine kinase phosphorelay osmosensor complex actively represses Ssk1p through phosphorylation in normal osmotic conditions. In the presence of hyperosmotic stress the Sln1p-Ypd1p osmosensor complex becomes inactive. This relieves repression of Ssk1p, which in turn activates the HOG pathway through phosphorylation of the redundant MAPK kinase kinases (MAPKKKs) Ssk2p and Ssk22p. These MAPKKKs activate the MAPK kinase (MAPKK) Pbs2p, which then activates Hog1p through phosphorylation. Activated Hog1p in turn upregulates the transcription of osmotic stress response genes such as GPD1, which encodes glycerol-3-phosphate dehydrogenase and HSP12, which encodes one of the major small heat shock proteins in yeast. Alternatively, a second input into this pathway, the Sho1p osmosensor, activates the Ste11p MAPKKK, which in turn activates the Pbs2p MAPKK, which activates Hog1p (Wurgler-Murphy and Saito, 1997).

Bottom Line: Biol.We have found that basal signaling through the HOG pathway is required to localize Mnn1-s to the Golgi in standard osmotic conditions.Mutations in HOG1 and LDR1 also perturb localization of intact Mnn1p, resulting in its loss from early Golgi compartments and a concomitant increase of Mnn1p in later Golgi compartments.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology, Vanderbilt University, Nashville, Tennessee 37235, USA.

ABSTRACT
The yeast alpha-1,3-mannosyltransferase (Mnn1p) is localized to the Golgi by independent transmembrane and lumenal domain signals. The lumenal domain is localized to the Golgi complex when expressed as a soluble form (Mnn1-s) by exchange of its transmembrane domain for a cleavable signal sequence (Graham, T. R., and V. A. Krasnov. 1995. Mol. Biol. Cell. 6:809-824). Mutants that failed to retain the lumenal domain in the Golgi complex, called lumenal domain retention (ldr) mutants, were isolated by screening mutagenized yeast colonies for those that secreted Mnn1-s. Two genes were identified by this screen, HOG1, a gene encoding a mitogen-activated protein kinase (MAPK) that functions in the high osmolarity glycerol (HOG) pathway, and LDR1. We have found that basal signaling through the HOG pathway is required to localize Mnn1-s to the Golgi in standard osmotic conditions. Mutations in HOG1 and LDR1 also perturb localization of intact Mnn1p, resulting in its loss from early Golgi compartments and a concomitant increase of Mnn1p in later Golgi compartments.

Show MeSH
Related in: MedlinePlus