Figure 1. Model for RPA2 function in stomatal terminal division regulation and DNA repair progression.
Stomata are plant-specific epidermal structures that consist of paired guard cells surrounding a pore. The opening and closing of these micro-valves facilitate carbon dioxide uptake for photosynthesis and reduce excessive water loss in plants.
Recently, a research group led by Prof. LE Jie at Institute of Botany, Chinese Academy of Sciences, finds a genetic suppressor of flp stomatal defects. They find RPA2a, a core subunit of Replication Protein A (RPA) complexes, acts downstream of core cell cycle genes of CDKB1s in ensuring the terminal division during stomatal development, ensuring the formation of paired guard cells to compose functional stomata units.
RPA is a heterotrimeric single-stranded DNA (ssDNA)-binding protein complex that is required for multiple aspects of DNA metabolism, including DNA replication, recombination, and repair. The homologues of each of the three RPA subunits (RPA1-3) are well conserved in eukaryotes, including human.
LE’s group demonstrate that the CDK-mediated phosphorylation at the N-terminus of RPA2a is essential for the RPA functions and the localization. And the Serine-11 and Serine-21 are evolutionarily conserved CDK-phosphorylation sites. Their results also reveal that being phosphorylation by CDK is required for RPA2a function in response DNA damage.
This research entitled “A conserved but plant specific CDK-mediated regulation of DNA replication protein A2 in the precise control of stomatal terminal division” has been published online in Proc. Natl. Acad. Sci. USA on August 19, 2019. YANG Kezhen is the first author and LE Jie is the corresponding author.
This work was supported by the National Natural Science Foundation of China.