Simple selection for end-product inhibitor-insensitive mutants in yeast

Area of Science:

• Biochemistry
• Molecular Biology
• Yeast Genetics

Background:

• Alpha-isopropylmalate synthetase is a key enzyme in leucine biosynthesis.
• End-product inhibition is a common regulatory mechanism in metabolic pathways.
• Yeast mutants can be selected based on resistance to toxic compounds.

Purpose of the Study:

• To identify and characterize yeast mutants resistant to trifluoroleucine.
• To investigate the genetic basis of trifluoroleucine resistance.
• To develop a simple screening method for these mutants.

Main Methods:

• Yeast strain cultivation and mutagenesis.
• Selection of trifluoroleucine-resistant mutants.
• Genetic analysis of dominance in diploid yeast.
• Enzyme assays for alpha-isopropylmalate synthetase activity.

Main Results:

• Trifluoroleucine-resistant yeast mutants were isolated.
• These mutants exhibit an end-product-insensitive alpha-isopropylmalate synthetase.
• The resistance phenotype is dominant in diploid yeast.

Conclusions:

• End-product insensitivity of alpha-isopropylmalate synthetase confers trifluoroleucine resistance.
• The dominant nature of these mutants allows for straightforward identification.
• This provides a facile screening method for studying leucine biosynthesis regulation in yeast.