Expression and function of AtMBD4L, the single gene encoding thenuclear DNA glycosylase MBD4L in Arabidopsis

NOTA F.; CAMBIAGNO D.A.; RIBONE P.; ALVAREZ M.E.

PLANT SCIENCE

ELSEVIER IRELAND LTD

Lugar: Amsterdam; Año: 2015 vol. 235 p. 122 - 129

0168-9452

DNA glycosylases recognize and excise damaged or incorrect bases from DNA initiating the base excisionrepair (BER) pathway. Methyl-binding domain protein 4 (MBD4) is a member of the HhH-GPD DNAglycosylase superfamily, which has been well studied in mammals but not in plants. Our knowledge onthe plant enzyme is limited to the activity of the Arabidopsis recombinant protein MBD4L in vitro. Tostart evaluating MBD4L in its biological context, we here characterized the structure, expression andeffects of its gene, AtMBD4L. Phylogenetic analysis indicated that AtMBD4L belongs to one of the sevenfamilies of HhH-GPD DNA glycosylase genes existing in plants, and is unique on its family. Two AtMBD4Ltranscripts coding for active enzymes were detected in leaves and flowers. Transgenic plants expressingthe AtMBD4L:GUS gene confined GUS activity to perivascular leaf tissues (usually adjacent to hydathodes),flowers (anthers at particular stages of development), and the apex of immature siliques. MBD4L-GFPfusion proteins showed nuclear localization in planta. Interestingly, overexpression of the full lengthMBD4L, but not a truncated enzyme lacking the DNA glycosylase domain, induced the BER gene LIG1 andenhanced tolerance to oxidative stress. These results suggest that endogenous MBD4L acts on particulartissues, is capable of activating BER, and may contribute to repair DNA damage caused by oxidative stress.