465 / 2019-02-27 10:30:57

A conserved but plant specific CDK-mediated regulation of DNA replication protein A2 in the precise control of stomatal terminal division

Stomata; Cell Division; Replication Protein A; CDK; Phosphorylation; DNA Damage

全体主题 > Cell Biology

The R2R3-MYB transcription factor FOUR LIPS (FLP) controls the stomatal terminal division through transcriptional repression of the cell cycle genes CDKB1s, CDKA;1, and CYCA2s. We mutagenized the weak mutant allele flp-1 seeds with ethylmethane sulfonate (EMS) and screened out a flp-1 suppressor 1 (fsp1) that showed suppressed flp-1 stomatal cluster phenotype. FSP1 encodes a RPA2a subunit of Replication Protein A (RPA) complexes that play important roles in DNA replication, recombination, and repair. Here, we show that FSP1/RPA2a function together with CDKB1s and CYCA2s in ensuring the stomatal lineage cell divisions and maintaining a normal guard cell size and DNA content. Furthermore, we provide a direct evidence for the existence of an evolutionally conserved but plant-specific CDK-mediated phosphorylation of RPA pathway. Serine-11 and Serine-21 at the N-terminus of RPA2a are putative CDK phosphorylation targets residues. The expression of the phosphorylation-mimic variant RPA2aS11,21/D partially complemented the defective cell division and hypersensitive response to DNA damage in cdkb1;1 1;2 mutants. Thus, our study provides a mechanistic understanding of the CDK-mediated phosphorylation of RPA in the precise control of cell cycle and DNA repair in plants.