MSW, a yeast gene coding for mitochondrial tryptophanyl-tRNA synthetase

Area of Science:

• Molecular Biology
• Yeast Genetics
• Mitochondrial Biology

Background:

• Saccharomyces cerevisiae mutants E569 and E606 exhibit defects in mitochondrial protein synthesis.
• These defects lead to deficiencies in respiratory components synthesized by mitochondrial ribosomes.

Purpose of the Study:

• To clone and characterize the gene responsible for complementing the mitochondrial protein synthesis defect in yeast mutants.
• To identify the specific function of the cloned gene in mitochondrial processes.

Main Methods:

• Cloning the wild-type MSW gene by yeast transformation using a genomic library.
• DNA sequencing of the cloned gene to determine its coding potential.
• Construction of a knockout mutant using in situ gene replacement to confirm gene function.

Main Results:

• The cloned gene, MSW, complements the mitochondrial protein synthesis defect.
• MSW encodes a protein homologous to tryptophanyl-tRNA synthetases from E. coli and B. stearothermophilus.
• A knockout mutant lacking MSW fails to charge mitochondrial tryptophanyl-tRNA, confirming MSW as the structural gene.

Conclusions:

• MSW is the structural gene for mitochondrial tryptophanyl-tRNA synthetase in Saccharomyces cerevisiae.
• Mitochondrial tryptophanyl-tRNA synthetase is essential for respiratory deficiency.
• The existence of a separate gene for cytoplasmic tryptophanyl-tRNA synthetase is implied.