A PSTAIRE-type cyclin-dependent kinase controls light responses in land plants

Abstract

Light is a critical signal perceived by plants to adapt their growth rate and direction. Although many signaling components have been studied, how plants respond to constantly fluctuating light remains underexplored. Here, we showed that in the moss Physcomitrium ( Physcomitrella ) patens , the PSTAIRE-type cyclin-dependent kinase PpCDKA is dispensable for growth. Instead, PpCDKA and its homolog in Arabidopsis thaliana control light-induced tropisms and chloroplast movements by probably influencing the cytoskeleton organization independently of the cell cycle. In addition, lower PpCDKA kinase activity was required to elicit light responses relative to cell cycle regulation. Thus, our study suggests that plant CDKAs may have been co-opted to control multiple light responses, and owing to the bistable switch properties of PSTAIRE-type CDKs, the noncanonical functions are widely conserved for eukaryotic environmental adaptation.

Experimental evolution of gene essentiality in bacteria

“…4) Mutations in multi-drug resistance genes: mutations of multi-drug resistanceassociated genes, such as rpoB and rpsL, are present in several evolved populations deleted for essential genes, suggesting a shared selective pressure resulting from drug treatment and deletion of essential genes (Supplemental Table 5). The suppressor mutations identified in our evolved populations deleted of essential genes may reflect the differential gene essentiality over evolutionary time in the pan-genome 11 and reproducibly changing gene essentiality across independently evolving populations. 13 Unexpectedly, as discussed above, for every essential gene mutated, we identified at least one population containing a suppressor mutation in another essential gene (Figure 2L).…”

“…9,10 Furthermore, essential genes can lose their essentiality during long-term evolution and acquire novel functions. [11][12][13] For instance, unlike the essential characteristics of the critical cell cycle regulator CDK1 in yeasts and animals, 14 plant PSTAIRE-type cyclin-dependent kinases, known as CDKAs (plant homologs of CDK1), play a role in environmental responses that is independent of the cell cycle, 11 likely after the acquisition of the plant-specific cyclin-dependent kinases, CDKBs. 15 Identifying genes that interact with essential genes can produce many potential benefits, both from a theoretical perspective, such as understanding the basic principle of cellular life, 16,17 and from a practical standpoint, such as addressing various challenges in synthetic biology 18 and combating drug resistance of infectious diseases.…”