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Plant Sci. 2015 Jun;235:122-9. doi: 10.1016/j.plantsci.2015.03.011. Epub 2015 Mar 20.

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

Author information

1
Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC, CONICET-UNC), Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Ciudad Universitaria, 5000 Córdoba, Argentina.
2
Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC, CONICET-UNC), Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Ciudad Universitaria, 5000 Córdoba, Argentina. Electronic address: malena@mail.fcq.unc.edu.ar.

Abstract

DNA glycosylases recognize and excise damaged or incorrect bases from DNA initiating the base excision repair (BER) pathway. Methyl-binding domain protein 4 (MBD4) is a member of the HhH-GPD DNA glycosylase superfamily, which has been well studied in mammals but not in plants. Our knowledge on the plant enzyme is limited to the activity of the Arabidopsis recombinant protein MBD4L in vitro. To start evaluating MBD4L in its biological context, we here characterized the structure, expression and effects of its gene, AtMBD4L. Phylogenetic analysis indicated that AtMBD4L belongs to one of the seven families of HhH-GPD DNA glycosylase genes existing in plants, and is unique on its family. Two AtMBD4L transcripts coding for active enzymes were detected in leaves and flowers. Transgenic plants expressing the 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-GFP fusion proteins showed nuclear localization in planta. Interestingly, overexpression of the full length MBD4L, but not a truncated enzyme lacking the DNA glycosylase domain, induced the BER gene LIG1 and enhanced tolerance to oxidative stress. These results suggest that endogenous MBD4L acts on particular tissues, is capable of activating BER, and may contribute to repair DNA damage caused by oxidative stress.

KEYWORDS:

BER system; HhH-GPD DNA glycosylases; Oxidative stress tolerance; Plant MBD4

PMID:
25900572
DOI:
10.1016/j.plantsci.2015.03.011
[Indexed for MEDLINE]

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