Farnesol kinase is involved in farnesol metabolism, ABA signaling and flower development in Arabidopsis

Abstract

SUMMARYFarnesol, which is toxic to plant cells at high concentrations, is sequentially phosphorylated to farnesyl phosphate and farnesyl diphosphate. However, the genes responsible for the sequential phosphorylation of farnesol have not been identified and the physiological role of farnesol phosphorylation has not been fully elucidated. To address these questions, we confirmed the presence of farnesol kinase activity in Arabidopsis (Arabidopsis thaliana) membranes and identified the corresponding gene (At5g58560, FOLK). Heterologous expression in recombinant yeast cells established farnesol as the preferred substrate of the FOLK-encoded kinase. Moreover, loss-of-function mutations in the FOLK gene abolished farnesol kinase activity, caused an abscisic acid-hypersensitive phenotype and promoted the development of supernumerary carpels under water-stress conditions. In wild-type plants, exogenous abscisic acid repressed FOLK gene expression. These observations demonstrate a role for farnesol kinase in negative regulation of abscisic acid signaling, and provide molecular evidence for a link between farnesol metabolism, abiotic stress signaling and flower development.

Remobilization of Phytol from Chlorophyll Degradation Is Essential for Tocopherol Synthesis and Growth of Arabidopsis

“…At1g78620 is weakly related to phytol kinases from different organisms, including Arabidopsis (At5g04490/ VTE5, 17.5% identity). The phytol kinase/VTE5 sequences cluster into a cyanobacterial/plant group containing At5g04490 (VTE5) and a related sequence (At5g58560, VTE5-like) (Fitzpatrick et al, 2011) and the second branch containing the phytol kinase domains that form fusion proteins with COG1836 sequences from Chlorobi and Firmicutes (Supplemental Figure 1) (Valentin et al, 2006).…”

Roles for farnesol and ABA in Arabidopsis flower development

“…In addition, folk flowers develop supernumerary carpels under water stress conditions. 6 From these observations, three hypotheses were developed:…”

“…5 Farnesol kinase and farnesyl phosphate kinase activities were recently confirmed in Arabidopsis seedling membranes. 6 Interestingly, CTP, ATP, GTP and UTP served as phosphoryl donors for conversion of [ Plant responses to abiotic stress are regulated by a multitude of hormone signals, transcription factors, microRNAs and ion channels. [7][8][9][10] Drought responses, for example, are mediated in part by the sesquiterpene phytohormone abscisic acid (ABA) and many genes have been identified that influence, or are influenced by, ABA signaling.…”

Mutant drought phenotype investigation : a look into effects of protein prenylation on water utilization in conditions of varying soil saturation and gene knockout.

“…This lipid, farnesol, can then undergo two steps of phosphorylation, creating the phosphorylated lipid farnesyl monophosphate (FP) after the first phosphorylation and farnesyl diphosphate (FPP) following the second phosphorylation (Fitzpatrick, Bhandari, & Crowell, 2011;Hemmerlin & Bach, 2000;Hemmerlin et al, 2006). The enzyme used to mediate the second step of this phosphorylation process is still unknown.…”

“…The enzyme used to mediate the second step of this phosphorylation process is still unknown. The FOLK gene was recently found to code for the enzyme, farnesyl kinase, used to mediate the phosphorelation of farnesyl to farnesyl monophosphate but not farnesyl monophosphate to farnesyl diphosphate (Fitzpatrick et al, 2011). After the conversion of FP to FPP, the fate of the farnesyl diphosphate is then protein prenylation, to attach the diphosphate lipid to a protein using the enzyme protein farnesyltransferase (PFT) (Crowell & Huizinga, 2009;Zhang & Casey, 1996).…”