Effect of zinc stress on plant mismatch repair

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

Córdoba

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

SAIB

Zn is an essential micronutrient that is involved in the functional activities of various proteins. However, metal excess may result in toxicity due to the formation of reactive oxygen species (ROS) by an indirect mechanism. Accumulation of ROS can induce peroxidation of lipids and oxidation of proteins and DNA bases, with 8-oxoguanine (8-oxoG) being the most frequent base lesion. Unrepaired 8-oxoG may be mutagenic since the oxidized base can direct incorporation of either C or A. Even more, the dGTP pool can also be oxidized. To minimize the burden of 8-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 by MutS proteins (MSH2, MSH6 and MSH7). To investigate the role of plant MMR system on the processing of oxidative DNA damage induced by Zn, we first evaluated the transcripts levels of MMR proteins by qRT-PCR. Our results demonstrate that MSH6 is induced by Zn in A. thaliana leaves, while MSH7 is repressed. Then, we identified msh6 T-DNA insertion mutants. Plants deficient in MSH6 show altered chlorophyll content and root elongation relative to wild-type plants. Finally, we generated transgenic plants that express β-glucuronidase (GUS) under the control of the MSH6 promoter. Taken together, our results suggest that MSH6 may be involved in Zn-induced DNA damage recognition.