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Updated: Aug 26, 2025
Genetic Studies of Human DNA Repair Proteins Using Yeast as a Model System
Published on: March 18, 2010
Evolutionary rescue of phosphomannomutase deficiency in yeast models of human disease
Ryan C Vignogna1, Mariateresa Allocca2,3, Maria Monticelli2,3,4
1Department of Biological Sciences, Lehigh University, Bethlehem, United States.
Abstract:
The most common cause of human congenital disorders of glycosylation (CDG) are mutations in the phosphomannomutase gene PMM2, which affect protein N-linked glycosylation. The yeast gene SEC53 encodes a homolog of human PMM2. We evolved 384 populations of yeast harboring one of two human-disease-associated alleles, sec53-V238M and sec53-F126L, or wild-type SEC53. We find that after 1000 generations, most populations compensate for the slow-growth phenotype associated with the sec53 human-disease-associated alleles. Through whole-genome sequencing we identify compensatory mutations, including known SEC53 genetic interactors. We observe an enrichment of compensatory mutations in other genes whose human homologs are associated with Type 1 CDG, including PGM1, which encodes the minor isoform of phosphoglucomutase in yeast. By genetic reconstruction, we show that evolved pgm1 mutations are dominant and allele-specific genetic interactors that restore both protein glycosylation and growth of yeast harboring the sec53-V238M allele. Finally, we characterize the enzymatic activity of purified Pgm1 mutant proteins. We find that reduction, but not elimination, of Pgm1 activity best compensates for the deleterious phenotypes associated with the sec53-V238M allele. Broadly, our results demonstrate the power of experimental evolution as a tool for identifying genes and pathways that compensate for human-disease-associated alleles.
Insights
Experimental evolution identified compensatory mutations in yeast, revealing that reduced PGM1 enzyme activity can restore protein glycosylation and growth in models of human congenital disorders of glycosylation (CDG).
Area of Science:
- Molecular Biology
- Genetics
- Yeast Model Systems
Background:
- Congenital disorders of glycosylation (CDG) are often caused by mutations in the phosphomannomutase gene PMM2, impacting protein N-linked glycosylation.
- The yeast SEC53 gene is a homolog of human PMM2, making it a valuable model for studying CDG pathogenesis.
Purpose of the Study:
- To identify compensatory mutations and pathways that can overcome the effects of disease-associated alleles in yeast.
- To investigate the role of PGM1 in compensating for defects in the PMM2/SEC53 pathway.
Main Methods:
- Evolved 384 populations of yeast harboring human-disease-associated SEC53 alleles (sec53-V238M, sec53-F126L) or wild-type SEC53 for 1000 generations.
- Utilized whole-genome sequencing to identify compensatory mutations.
- Performed genetic reconstruction and enzymatic assays to validate the function of identified mutations.
Main Results:
- Most evolved yeast populations compensated for the slow-growth phenotype associated with sec53 disease alleles.
- Compensatory mutations were enriched in known SEC53 interactors and in PGM1, a homolog of a gene linked to Type 1 CDG.
- Evolved PGM1 mutations were dominant and allele-specific, restoring protein glycosylation and growth in yeast with the sec53-V238M allele; reduced PGM1 activity provided the best compensation.
Conclusions:
- Experimental evolution is a powerful tool for discovering genetic interactions and compensatory mechanisms for human disease alleles.
- PGM1 plays a critical role in compensating for PMM2/SEC53 defects, highlighting a conserved pathway in glycosylation.
