Johansson M, McWatters HG, Bakó L, Takata N, Gyula P, Hall A, Somers DE, Millar AJ, Eriksson ME
Partners in time: EARLY BIRD associates with ZEITLUPE and regulates the speed of the Arabidopsis clock
Plant Physiology: 2011 155:2108-2122
The circadian clock of the model plant Arabidopsis thalianais made up of a complex series of interacting feedback loopswhereby proteins regulate their own expression across day andnight. early bird (ebi) is a circadian mutation that causesthe clock to speed up: ebi plants have short circadian periods,early phase of clock gene expression and are early flowering.We show that EBI associates with ZEITLUPE (ZTL), known to actin the plant clock as a post-translational mediator of proteindegradation. However, EBI is not degraded by its interactionwith ZTL. Instead, ZTL counteracts the effect of EBI duringthe day and increases it at night, modulating the expressionof key circadian components. The partnership of EBI with ZTLreveals a novel mechanism involved in controlling the complextranscription-translation feedback loops of the clock. Thiswork highlights the importance of cross-talk between the ubiquitinationpathway and transcriptional control for regulation of the plantclock.
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