Fus3 controls Ty1 transpositional dormancy through the invasive growth MAPK pathway

Area of Science:

• Molecular Biology
• Yeast Genetics
• Signal Transduction

Background:

• The mating pheromone response pathway in yeast involves the Fus3 mitogen-activated protein kinase (MAPK).
• Fus3 is known to inhibit Ty1 retrotransposition and haploid invasive growth.
• The precise mechanisms by which Fus3 regulates these processes are not fully understood.

Purpose of the Study:

• To investigate the role of Fus3 kinase activity and dosage in regulating Ty1 retrotransposition and haploid invasive growth.
• To elucidate the relationship between the invasive growth pathway and Fus3-mediated inhibition of Ty1 transposition.

Main Methods:

• Analysis of kinase-defective fus3-K42R allele.
• Overexpression studies of wild-type and mutant Fus3.
• Epistatic analysis using transcription factors Ste12 and Tec1.
• Genetic manipulation of the invasive growth pathway (TEC1 overexpression, STE11-4, hog1 deletion).

Main Results:

• Kinase activity is essential for Fus3 to inhibit Ty1 transposition and invasive growth.
• Increasing Fus3 dosage enhances its inhibitory effects.
• Fus3-mediated inhibition of Ty1 transposition requires the invasive growth pathway transcription factors Ste12 and Tec1.
• Activation of the invasive growth pathway leads to concomitant activation of Ty1 transposition.

Conclusions:

• Fus3 kinase activity and dosage coordinately regulate Ty1 transposition and invasive growth.
• The haploid invasive growth pathway activates Ty1 transposition at both transcriptional and post-transcriptional levels.
• Fus3 inhibits Ty1 transposition by negatively regulating the invasive growth pathway.