Functional characterization of the Arabidopsis gene encoding the DNA glycosylase MBD4

ALVAREZ MARIA ELENA; NOTA FLORENCIA

Congreso; 11th International Plant Molecular Biology Meeting 2015; 2015

DNA glycosylases are ancient enzymes that recognize and excise damaged bases in DNA, initiating the base excision repair system (BER) that replaces the altered molecule by a healthy one. In addition, some of these enzymes lead to active DNA demethylation by incorporating C in place of 5-mC. Methyl-binding domain protein 4 (MBD4) is a member of the HhH-GPD DNA glycosylase superfamily scarcely studied in plants. Recently, we provided the first biological characterization of the single gene encoding this enzyme in Arabidopsis (MBD4-like; MBD4L). The AtMBD4L gene is active in the proximity to hydathodes, flowers at certain developmental stages, and particular tissues of the silique, having a different expression pattern than other known DNA glycosylase genes. AtMBD4L encodes a nuclear enzyme whose overexpression activates BER genes and provides tolerance to oxidative stress. To learn more about the function of this enzyme, we analyzed the phenotypes derived from its deficiency. Our results indicated that MBD4L modulates plant growth, silique generation and flowering time, with different biological effects than ROS or DME. These findings suggest a non-redundant and quite specific activity for MBD4L in vivo, and point out some putative genomic targets that could be useful to study the natural substrates of this enzyme.