A Rab escort protein regulates the MAPK pathway that controls filamentous growth in yeast

Abstract

MAPK pathways regulate different responses yet can share common components. Although core regulators of MAPK pathways are well known, new pathway regulators continue to be identified. Overexpression screens can uncover new roles for genes in biological processes and are well suited to identify essential genes that cannot be evaluated by gene deletion analysis. In this study, a genome-wide screen was performed to identify genes that, when overexpressed, induce a reporter (FUS1-HIS3) that responds to ERK-type pathways (Mating and filamentous growth or fMAPK) but not p38-type pathways (HOG) in yeast. Approximately 4500 plasmids overexpressing individual yeast genes were introduced into strains containing the reporter by high-throughput transformation. Candidate genes were identified by measuring growth as a readout of reporter activity. Fourteen genes were identified and validated by re-testing: two were metabolic controls (HIS3, ATR1), five had established roles in regulating ERK-type pathways (STE4, STE7, BMH1, BMH2, MIG2) and seven represent potentially new regulators of MAPK signaling (RRN6, CIN5, MRS6, KAR2, TFA1, RSC3, RGT2). MRS6 encodes a Rab escort protein and effector of the TOR pathway that plays a role in nutrient signaling. MRS6 overexpression stimulated invasive growth and phosphorylation of the ERK-type fMAPK, Kss1. Overexpression of MRS6 reduced the osmotolerance of cells and phosphorylation of the p38/HOG MAPK, Hog1. Mrs6 interacted with the PAK kinase Ste20 and MAPKK Ste7 by two-hybrid analysis. Based on these results, Mrs6 may selectively propagate an ERK-dependent signal. Identifying new regulators of MAPK pathways may provide new insights into signal integration among core cellular processes and the execution of pathway-specific responses.

New Features Surrounding the Cdc42-Ste20 Module that Regulates MAP Kinase Signaling in Yeast

“…S3D ). This result is consistent with expression profiling data from our laboratory (Adhikari and Cullen, 2014; Chavel et al, 2014; Chow et al, 2019) and with the fact that overexpression of CDC24 does not induce fMAPK pathway activity or invasive growth in S. cerevisiae (Jamalzadeh et al, 2020). Thus, phosphorylation of Cdc24p and positive feedback are not major determinants in the regulation of the fMAPK pathway.…”

“…3E , control, 1h; 3h), which induces phosphorylation of the fMAPK Kss1p (Basu et al, 2020; González and Cullen, 2022; Prabhakar et al, 2021). As reported (Basu et al, 2020; Jamalzadeh et al, 2020) P∼Kss1p levels increased in galactose over time. Overexpression of BMH1 induced high levels of P∼Kss1p over the entire time course of the experiment ( Fig.…”

“…Bmh1p and Bmh2p are members of the 14-3-3 family of proteins (van Hemert et al, 2001) which were previously identified as regulators of the fMAPK pathway that interact with and function through Ste20p (Roberts et al, 1997). Bmh1p and Bmh2p were identified by our laboratory in a genome-wide screen for proteins that when overexpressed stimulate the activity of the fMAPK pathway (Jamalzadeh et al, 2020). Although these proteins were found to associate with Ste20p, their role in regulating the three Ste20p-dependent pathways has yet to be fully explored (Fig.…”

Biosynthesis of silver nanoparticles with antimicrobial and anticancer properties using two novel yeasts

“…Afterwards, they were dehydrated in tert-butoxide solution of 50%, 70%, 80%, 90% and three times in 100%, for 10 min each. Finally they were dried in a freeze-dryer for a period of 10 min 23 . The specimens were then examined with a TEM-1230 (JEOL, Japan).…”

Transcriptomic analysis of the fungus Graphilbum sp. in response to the pine wood nematode

“…Rab7 was downregulated and involved in MAPK pathway and small GTPase mediated signal transduction. The small GTPase protein Rab escort protein of MAPK pathways provides signal integration among core cellular processes and execution of pathway‐specific responses [39]. The expression of Ras genes was upregulated in response to PWNs, and involved in both the GTPase‐mediated signal, SNARE binding and MAPK pathways.…”