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Comparative Analysis of Transmembrane Regulators of the Filamentous Growth Mitogen-Activated Protein Kinase Pathway

Hema Adhikari1, Lauren M Caccamise1, Tanaya Pande1

  • 1Department of Biological Sciences at the University at Buffalo, Buffalo, New York, USA.

Eukaryotic Cell
|June 28, 2015
PubMed

Insights

Transmembrane proteins Msb2p, Sho1p, and Opy2p regulate yeast filamentous growth. Despite associating, they exhibit distinct localization and turnover rates, fine-tuning the cellular response.

Area of Science:

  • Cell Biology
  • Microbiology
  • Molecular Biology

Background:

  • Filamentous growth is a crucial microbial differentiation process regulated by complex signaling pathways.
  • In budding yeast, the Cdc42p-dependent mitogen-activated protein kinase (MAPK) pathway is central to filamentous growth.
  • Several transmembrane (TM) proteins, including Msb2p, Sho1p, and Opy2p, are known regulators of this pathway.

Purpose of the Study:

  • To compare the common and unique features of TM proteins Msb2p, Sho1p, and Opy2p in regulating filamentous growth.
  • To elucidate the roles of protein localization, turnover, and signaling in the filamentous growth pathway.
  • To understand how individual TM protein specialization contributes to the overall filamentation response.

Main Methods:

  • Coimmunoprecipitation analysis to assess protein associations.
  • Fluorescence microscopy to determine protein localization patterns.
  • Rate of turnover analysis from the plasma membrane (PM).
  • Genetic analysis of cells overexpressing TM proteins.

Main Results:

  • Msb2p, Sho1p, and Opy2p were found to associate with each other.
  • These proteins displayed distinct localization patterns at the plasma membrane.
  • Differential turnover rates from the PM were observed, with Msb2p and Opy2p showing rapid turnover compared to Sho1p.
  • Msb2p signaling from the PM was identified as a rate-limiting step in MAPK signaling.
  • Overexpression of TM proteins led to unique cellular phenotypes.

Conclusions:

  • Each TM regulator (Msb2p, Sho1p, Opy2p) possesses unique regulatory patterns and functions in filamentous growth.
  • Protein specialization among TM regulators is critical for fine-tuning and potentially diversifying the filamentation response.
  • Understanding these distinct roles provides insight into the complex regulation of microbial differentiation.

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