Effect of zinc stress on plant mismatch repair

SPAMPINATO, C.; MONCHIETTI, PAULA; GONZALEZ, VALENTINA

Córdoba

Congreso; LII Reunión Anual de la Sociedad Argentina de Investigación Bioquímica (SAIB); 2016

SAIB

Zn is an essentialmicronutrient that is involved in the functional activities of variousproteins. However, metal excess may result in toxicity due to the formation ofreactive oxygen species (ROS) by an indirect mechanism. Accumulation of ROS caninduce peroxidation of lipids and oxidation of proteins and DNA bases, with8-oxoguanine (8-oxoG) being the most frequent base lesion. Unrepaired 8-oxoGmay be mutagenic since the oxidized base can direct incorporation of either Cor A. Even more, the dGTP pool can also be oxidized. To minimize the burden of8-oxoG several DNA repair pathways exist. One of them is the mismatch repair (MMR)system. The first step of the pathway involves recognition of the DNA lesion byMutS proteins (MSH2, MSH6 and MSH7). To investigate the role of plant MMR systemon the processing of oxidative DNA damage induced by Zn, we first evaluated thetranscripts levels of MMR proteins by qRT-PCR. Our results demonstrate thatMSH6 is induced by Zn in A. thalianaleaves, while MSH7 is repressed. Then, we identified msh6 T-DNAinsertion mutants. Plants deficient in MSH6 show altered chlorophyll contentand root elongation relative to wild-type plants. Finally, we generatedtransgenic plants that express β-glucuronidase (GUS) under the control of theMSH6 promoter. Taken together, our results suggest that MSH6 may be involved inZn-induced DNA damage recognition.