A High-Throughput Assay for DNA Replication Inhibitors Based upon Multivariate Analysis of Yeast Growth Kinetics

Area of Science:

• Molecular Biology
• Cell Biology
• Biochemistry

Background:

• The Mcm2-7 complex functions as the core of the eukaryotic replicative helicase, crucial for DNA replication and cell cycle control.
• Regulation of the Mcm2-7 complex is vital for cellular S-phase progression, yet few small-molecule inhibitors are known.
• Genetic interactions, specifically synthetic growth defects, provide a basis for identifying inhibitors of protein complexes.

Purpose of the Study:

• To develop a high-throughput screening (HTS) assay for identifying small molecules that inhibit the Mcm2-7 replicative helicase.
• To leverage synthetic growth defects in a characterized mcm mutant (mcm2DENQ) to discover novel inhibitors.
• To enhance assay sensitivity, reproducibility, and the range of detectable phenotypes using advanced analytical methods.

Main Methods:

• Development of an HTS assay utilizing a specific mcm mutant (mcm2DENQ) to detect synthetic growth defects.
• Initial screening identified aphidicolin (DNA polymerase alpha inhibitor) and XL413 (CDC7 kinase inhibitor) as compounds preferentially inhibiting the mcm mutant.
• Implementation of a strategy combining cell growth kinetics analysis with linear discriminant analysis (LDA) to improve assay performance.

Main Results:

• The HTS assay successfully identified compounds that preferentially inhibit the growth of the mcm2DENQ mutant strain.
• Linear discriminant analysis significantly enhanced assay sensitivity and reproducibility, overcoming limitations of small assay windows.
• The combined approach enabled the capture of a broader spectrum of synthetic growth inhibition phenotypes, creating a versatile platform.

Conclusions:

• A novel and robust HTS assay has been established for discovering inhibitors of the Mcm2-7 helicase complex.
• The integration of cell growth kinetics and LDA provides a powerful and adaptable platform for drug discovery in DNA replication.
• This methodology facilitates the identification of small molecules that specifically target critical regulators of eukaryotic DNA replication.