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Cdc42p-interacting protein Bem4p regulates the filamentous-growth mitogen-activated protein kinase pathway

Andrew Pitoniak1, Colin A Chavel1, Jacky Chow1

  • 1Department of Biological Sciences, SUNY-Buffalo, Buffalo, New York, USA.

Molecular and Cellular Biology
|November 12, 2014
PubMed

Insights

Bem4p protein specifically regulates the filamentous growth pathway in yeast by interacting with key signaling proteins. This interaction ensures pathway specificity for cell polarity and signaling under nutrient limitation.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • The Rho GTPase Cdc42p is crucial for cell polarity and signaling but its context-specific functions are not fully understood.
  • Understanding how proteins like Cdc42p are directed to specific cellular pathways is essential for comprehending cellular regulation.

Purpose of the Study:

  • To investigate the role of Cdc42p-interacting protein Bem4p in regulating specific cellular pathways.
  • To elucidate the mechanism by which Bem4p confers specificity to mitogen-activated protein kinase (MAPK) pathways.

Main Methods:

  • Yeast genetics and molecular biology techniques were employed.
  • Protein-protein interaction studies, including association with plasma membrane proteins and guanine nucleotide exchange factors, were performed.
  • Analysis of MAPK pathway activation and protein localization during filamentous growth was conducted.

Main Results:

  • Bem4p specifically regulates the filamentous growth MAPK pathway, distinct from mating and high-osmolarity glycerol response (HOG) pathways.
  • Bem4p associates with Sho1p at the plasma membrane, influencing MAPK activity and cell polarization.
  • Bem4p interacts with Cdc24p and Ste11p, contributing to Cdc24p localization and filamentous growth pathway activation.

Conclusions:

  • Bem4p is identified as a novel regulator of the filamentous growth MAPK pathway in Saccharomyces cerevisiae.
  • Bem4p's interaction with general signaling proteins like Cdc42p and Ste11p promotes pathway-specific responses.
  • Bem4p plays a critical role in directing Cdc42p-mediated signaling towards filamentous growth under specific environmental conditions.

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