Characterization of yeast polymerase gamma mutations associated with human disorders
(2010)
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- Authors
- Supervisors
- Foury, Françoise
- Abstract
- (en) DNA pol g is the sole polymerase responsible for mtDNA replication. 150 mutations associated with human disorders have been identified. The patients often have several different mutations in cis or in trans, and thus it is difficult to distinguish pathogenic mutations and to establish the impact of each mutation in the disorder. We have introduced 7 mip1 mutations in Mip1p, the yeast pol g, alone or in combination, identical to those found in patients. The aim of this work is to determine the contribution of each mutation to the disorder and the role of these amino acids in the pol g function. R607P, T716P, M920R and T716P-F921I elicit loss of mtDNA. Except for the R607P, Mip1p levels are not detectable suggesting that the protein structure is impaired. Q264H, R607C and F921I allow maintenance of the mtDNA. Whereas the Q264H, R607C and T716P-F921I/Q264H elicit high instability of the mtDNA, the F921I has only a mild effect and shows an increase in the punctual mutation rate compared to wild-type. No effect was observed for the K903C supporting the view that the human equivalent is a SNP. In these mutants, Mip1p levels are not, or weakly, decreased. The gap-filling activity is lower for the Q264H, R607C/P, and similar to wild-type for F921I and K903C. Processive DNA synthesis is decreased in all mutants whereas DNA binding affinity is not (R607C, F921I) or moderately (Q264H, R607P) decreased. The 3’-5’ exonuclease activity is the highest in R607P, similar to wild-type in F921I and R607C, and lower in Q264H. Our data suggest that all mutations, except K903C, play a role in the disease. In conclusion, characterization of human mutations associated with mitochondrial disorders in yeast can generate informations that can be used for understanding the molecular defects in humans.
- Affiliations
Citations
Cochonneau, D. (2010). Characterization of yeast polymerase gamma mutations associated with human disorders. https://hdl.handle.net/2078.5/129663