Characterization of a novel family of WNK protein kinases with reference to circadian rhythms in A.thaliana.

Abstract

We recently isolated a novel type of protein kinase, named AtWNK1, which shows an in vitro ability to phosphorylate the APRR3 member of the APRR1/TOC1 quintet that has been implicated in a mechanism underlying circadian rhythms in Arabidopsis thaliana. We here address two issues, one general and one specific, as to this novel protein kinase. How many WNK family members are present in this higher plant? Whether or not are other WNK members also relevant to circadian rhythms? Among 9 WNK family members, thus identified, it was found that not only the transcription of the WNK1 gene, but also those of three other members (WNK2, WNK4, and WNK6) are under the control of circadian rhythms. These results, together with those form analyses of mutant plants, will be discussed with reference to the mechanisms underlying circadian rhythms in Arabidopsis.