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Postrecruitment Function of Yeast Med6 Protein during the Transcriptional Activation by Mediator Complex

Gwang Sik Kim1, Young Chul Lee1

  • 1School of Biological Science and Technology, Hormone Research Center, Chonnam National University, Gwangju, Republic of Korea.

Biochemistry Research International
|July 12, 2018
PubMed

Insights

The Med6 protein is crucial for Mediator complex function in yeast. Specific mutations in Med6 disrupt its association with Mediator, impairing transcriptional activation and cell viability, highlighting its role in post-recruitment steps.

Area of Science:

  • Molecular Biology
  • Genetics
  • Biochemistry

Background:

  • The Mediator complex is essential for regulating gene transcription.
  • The precise role of the Med6 protein (Med6p) within the Mediator complex is not fully understood.
  • Med6p is a conserved component of Mediator complexes across evolution.

Purpose of the Study:

  • To investigate the functional significance of specific regions within Saccharomyces cerevisiae Med6p (scMed6p).
  • To elucidate the role of scMed6p in Mediator complex assembly and transcriptional regulation.

Main Methods:

  • Generation and genetic analysis of scMed6p internal deletion mutants.
  • Assessment of mutant protein stability and Mediator complex association.
  • In vitro transcription assays using recombinant Med6p mutants.
  • Artificial recruitment assays to evaluate Mediator recruitment and transcriptional activation.

Main Results:

  • Three distinct regions (Δ2, Δ5, Δ6) of scMed6p are critical for cell viability and conserved among homologs.
  • The Med6p-Δ2 mutant showed reduced stability and Mediator association.
  • Mutants Δ5 and Δ6 failed to restore in vitro transcriptional defects, with Δ6 specifically blocking TBP recruitment and reporter gene expression.

Conclusions:

  • Med6p plays a vital role in Mediator complex function, particularly in post-recruitment steps essential for transcriptional activation.
  • Specific deletions in Med6p can lead to instability, impaired Mediator association, and loss of transcriptional regulatory function.
  • These findings provide critical insights into the structure-function relationship of Med6p in the Mediator complex.

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