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Measurement of mRNA Decay Rates in Saccharomyces cerevisiae Using rpb1-1 Strains
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The structure of the checkpoint clamp 9-1-1 complex and clamp loader Rad24-RFC in Saccharomyces cerevisiae

Wei Liu1

  • 1School of Life Sciences, University of Science and Technology of China, Hefei, 230027, China.

Biochemical and Biophysical Research Communications
|June 12, 2019
PubMed

Insights

The 9-1-1 complex, crucial for DNA damage response, was structurally characterized. Its flexible C-tail and interaction with Rad24-RFC were revealed, advancing cell cycle checkpoint understanding.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Structural Biology

Background:

  • The 9-1-1 complex (Rad9-Hus1-Rad1) is vital for activating cell cycle checkpoints upon DNA damage.
  • Loading of the 9-1-1 complex by Rad24-RFC at DNA damage sites is essential for checkpoint activation.
  • Limited structural data exists for the intact 9-1-1 complex and its interaction with Rad24-RFC.

Purpose of the Study:

  • To determine the cryo-EM structure of the intact 9-1-1 complex in Saccharomyces cerevisiae.
  • To identify the C-terminal module of Ddc1/Rad9 and elucidate its role in checkpoint activation.
  • To visualize the interaction between the 9-1-1 complex and the Rad24-RFC clamp loader.

Main Methods:

  • Cryo-electron microscopy (cryo-EM) was employed to determine the structure of the intact 9-1-1 complex.
  • Structural analysis focused on identifying key domains, including the Ddc1 C-tail.
  • The study captured snapshots of the Rad24-RFC complex interacting with the 9-1-1 complex.

Main Results:

  • The complete structure of the intact 9-1-1 complex from S. cerevisiae was determined.
  • A flexible C-terminal module of Ddc1/Rad9 was identified and characterized.
  • The structural flexibility of the Ddc1 C-tail was found to be critical for Mec1/Ddc2 activation in G1/G2 phases.
  • The interaction interface between the 9-1-1 complex and Rad24-RFC was visualized.

Conclusions:

  • The study provides the first structural insights into the intact 9-1-1 complex and its interaction with Rad24-RFC.
  • The flexible Ddc1 C-tail plays a crucial role in DNA damage checkpoint activation.
  • These findings enhance the understanding of the clamp-loading mechanism in DNA repair and cell cycle regulation.

Keywords:
9-1-1 complexDNA damage responseDdc1 C-tailMec1/Ddc2Rad24-RFC

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