TheS. cerevisiae nitrogen starvation-induced Yvh1p and Ptp2p phosphatases play a role in control of sporulation

Abstract

Starvation for nitrogen in the absence of a fermentable carbon source causes diploid Saccharomyces cerevisiae cells to leave vegetative growth, enter meiosis, and sporulate; the former nutritional condition also induces expression of the YVH1 gene that encodes a protein phosphatase. This correlation prompted us to determine whether the Yvh1p phosphatase was a participant in the network that controls the onset of meiosis and sporulation. We found that expression of the IME2 gene, encoding a protein kinase homologue required for meiosis‐ and sporulation‐specific gene expression, is decreased in a yvh1 disrupted strain. We also observed a decrease, albeit a smaller one, in the expression of IME1 which encodes an activator protein required for IME2 expression. Under identical experimental conditions, expression of the MCK1 and IME4 genes (which promote sporulation but do not require Ime1p for expression) was not affected. These results demonstrate the specificity of the yvh1 disruption phenotype. They suggest that decreased steady‐state levels of IME1 and IME2 mRNA were not merely the result of non‐specific adverse affects on nucleic acid metabolism caused by the yvh1 disruption. Sporulation of a homozygous yvh1 disruption mutant was delayed and less efficient overall compared to an isogenic wild‐type strain, a result which correlates with decreased IME1 and IME2 gene expression. We also observed that expression of the PTP2 tyrosine phosphatase gene (a negative regulator of the osmosensing MAP kinase cascade), but not the PTP1 gene (also encoding a tyrosine phosphatase) was induced by nitrogen‐starvation. Although disruption of PTP2 alone did not demonstrably affect sporulation or IME2 gene expression, sporulation was decreased more in a yvh1, ptp2 double mutant than in a yvh1 single mutant; it was nearly abolished in the double mutant. These data suggest that the YVH1 and PTP2 encoded phosphatases likely participate in the control network regulating meiosis and sporulation. Expression of YVH1 and PTP2 was not affected by nitrogen source quality (asparagine compared to proline) suggesting that nitrogen starvation‐induced YVH1 and PTP2 expression and sensitivity to nitrogen catabolite repression are on two different branches of the nitrogen regulatory network.

Rapamycin-modulated transcription defines the subset of nutrient-sensitive signaling pathways directly controlled by the Tor proteins

“…The transcription profile revealed that rapamycin does not cause yeast growing in rich media to appear nitrogen-starved. Two genes that are normally induced by nitrogen starvation, YVH1 and PTP2 (33), are repressed or unchanged, respectively, after treatment with rapamycin. Also, of 52 genes of unknown function that were shown to be sensitive to nitrogen starvation (34), only 19% (10 genes) were appropriately modulated in the response to rapamycin.…”

TheDrosophiladual-specificity ERK phosphatase DMKP3 cooperates with the ERK tyrosine phosphatase PTP-ER

“…This interaction is reminiscent of the yeast DSP Yvh1 and the tyrosine phosphatase Ptp2, which have little effect when mutated alone, but double mutants are sporulation defective (Park et al, 1996). As there are five additional MKPs in the Drosophila genome (Morrison et al, 2000), negative regulation of ERK by a combinatorial network of those phosphatases will probably reveal high redundancy as well.…”

A putative dual-specific protein phosphatase encoded by YVH1 controls growth, filamentation and virulence in Candida albicans

“…In the model yeast Saccharomyces cerevisiae, YVH1, one of the DSPs, was first identified as a vaccinia VH1 homologue (Guan et al, 1992). Deletion of YVH1 in S. cerevisiae causes defects in vegetative growth (particularly at lower temperatures), sporulation and glycogen accumulation, and transcription of YVH1 is induced by low temperature and nitrogen starvation (Beeser & Cooper, 2000;Guan et al, 1992;Park et al, 1996;Sakumoto et al, 1999Sakumoto et al, , 2001). However, even in S. cerevisiae, the exact function of YVH1 remains to be elucidated.…”