Subnuclear localization of the MBD4L DNA glycosylase splicing isoforms

TORRES J.R; COBO S; CECCHINI N; LESCANO I; NOTA F; ALVAREZ M.E

Villarrica

Congreso; XII reunion de Biologia vegetal; 2017

Chilean Society of Plant Biology

 DNA glycosylases are key enzymes fororganisms? genome stability mediating DNA damage repair. Among them, MBD4L is anuclear Arabidopsis DNA glycosylase acting during stress conditions.Interestingly, MBD4L gene can generate two isoformsthrough the retention of a protein coding cryptic intron (exitron). It is believedthat exitron splicing events result in protein versions with alternative functionaldomains and/or post translational modifications. Taking this into account, weanalyzed MBD4L splicing isoforms transcript levels, subcelular localization andcontribution to damaged DNA correction. We found that the MBD4L alternative transcripts changed their relative levels depending on thestress applied. Surprisingly, when expressed as GFP fusions each of the MBD4isoforms located at different subnuclear compartments in both Arabidopsis and Nicotiana benthamiana plants. Moreover, some stresses induceddynamic changes in enzyme subnuclear localization. On the other hand, althoughshowing distinctive localization the overexpression of both MBD4L isoformsincreased resistance to a DNA damaging agent. Altogether, our results indicatethat MBD4L location can be driven by exitron alternative splicing mechanisms.However, additional levels of control may determine differential subcellularrequirements for MBD4L isoforms under particular circumstances. A putative modelfor MBD4L nuclear role/localization will be presented. DNA glycosylases are key enzymes fororganisms? genome stability mediating DNA damage repair. Among them, MBD4L is anuclear Arabidopsis DNA glycosylase acting during stress conditions.Interestingly, MBD4L gene can generate two isoformsthrough the retention of a protein coding cryptic intron (exitron). It is believedthat exitron splicing events result in protein versions with alternative functionaldomains and/or post translational modifications. Taking this into account, weanalyzed MBD4L splicing isoforms transcript levels, subcelular localization andcontribution to damaged DNA correction. We found that the MBD4L alternative transcripts changed their relative levels depending on thestress applied. Surprisingly, when expressed as GFP fusions each of the MBD4isoforms located at different subnuclear compartments in both Arabidopsis and Nicotiana benthamiana plants. Moreover, some stresses induceddynamic changes in enzyme subnuclear localization. On the other hand, althoughshowing distinctive localization the overexpression of both MBD4L isoformsincreased resistance to a DNA damaging agent. Altogether, our results indicatethat MBD4L location can be driven by exitron alternative splicing mechanisms.However, additional levels of control may determine differential subcellularrequirements for MBD4L isoforms under particular circumstances. A putative modelfor MBD4L nuclear role/localization will be presented.