A yeast system to study the role of Arabidopsis thaliana MutS heterodimer

GÓMEZ, R.; SPAMPINATO, C.

Puerto Madryn

Congreso; XLVI Reunión Anual de la Sociedad Argentina de Investigación Bioquímica; 2010

SAIB

The mismatch repair system (MMR) is a highly conserved DNA repair pathway essential for the correct maintenance of genetic information across many generations. The first step of the pathway involves recognition of the mismatch by MutS homodimers in bacteria or MutS homologs (MSH) heterodimers in eukaryotes (MutS and MutS ). Higher plants contain an additional heterodimer, named MutS (MSH2-MSH7). To analyze the specific function of this heterodimer from A. thaliana, we expressed MSH2 and MSH7 both individually and as a complex in Saccharomyces cerevisiae. Strains used include E134 and its mutant derivative lacking msh2 (DAG60). Both strains share the same genetic background and contain three reporter genes to estimate mutation rates. The loci lys2::InsE and his7-2 are frameshift reversion reporters, while the CAN1 locus scores a broad variety of forward mutations. Our results indicate that expression of the individual AtMSH2 or AtMSH7 in both strains did not affect the mutation rates of the examined reporter genes. However, the co-expression of both subunits in strain E134 led to 4-fold increase in the mutation rate of the CAN1 reporter. These data suggest that AtMSH2 cannot complement the yeast msh2 disruption, and that AtMutS negatively affects yeast MMR function, with the exception of frasmeshift lesions. A. thaliana, we expressed MSH2 and MSH7 both individually and as a complex in Saccharomyces cerevisiae. Strains used include E134 and its mutant derivative lacking msh2 (DAG60). Both strains share the same genetic background and contain three reporter genes to estimate mutation rates. The loci lys2::InsE and his7-2 are frameshift reversion reporters, while the CAN1 locus scores a broad variety of forward mutations. Our results indicate that expression of the individual AtMSH2 or AtMSH7 in both strains did not affect the mutation rates of the examined reporter genes. However, the co-expression of both subunits in strain E134 led to 4-fold increase in the mutation rate of the CAN1 reporter. These data suggest that AtMSH2 cannot complement the yeast msh2 disruption, and that AtMutS negatively affects yeast MMR function, with the exception of frasmeshift lesions.