Alternative splicing of an exitron determines the subnuclear localization of the Arabidopsis DNA glycosylase MBD4L under heat stress

ALVAREZ MARÍA E

PLANT JOURNAL

WILEY-BLACKWELL PUBLISHING, INC

Año: 2022

0960-7412

NA glycosylases are critical enzymes that recognize small base lesions in DNA and trigger their repair to preserve genome integrity. The Arabidopsis MBD4-like (MBD4L) DNA glycosylase improves tolerance to genotoxic stress. This enzyme is encoded by a single gene carrying an exonic intron (exitron) at its 5′ region. Although alternative splicing (AS) of exitrons (protein-coding cryptic introns within exons) is suspected to increase protein diversity, phenotypes associated to exitron removal or retention are only known for a few genes. Here, we show that AS of the MBD4L exitron determines the generation of two enzyme isoforms with different subnuclear localization. Both isoforms conserve the catalytic domain but are directed to either the nucleoplasm or the nucleolus. Interestingly, heat stress regulates the AS of the MBD4L exitron and increases the relative abundance of the nucleolar variant. This process depends on the splicing factors NTR1 and RS31. Next, we generated transgeni