AtGRP7, a nuclear RNA-binding protein as a component of a circadian-regulated negative feedback loop in Arabidopsis thaliana

• Published in: Proceedings of the National Academy of Sciences - PNAS 1997-08, Vol.94 (16), p.8515-8520
• Main Authors: Heintzen, C. (Dartsmouth Medical School, Hanover, NH.), Nater, M, Apel, K, Staiger, D
• Format: Article
• Language: English
• Subjects: Arabidopsis - physiology; ARABIDOPSIS THALIANA; ARN; ARN MENSAJERO; ARN MESSAGER; BINDING PROTEINS; Biochemistry; BIOLOGICAL RHYTHMS; Biological Sciences; CIRCADIAN RHYTHM; Control loops; EXPRESION GENICA; EXPRESSION DES GENES; Feedback; Flowers & plants; GENE EXPRESSION; Gene expression regulation; GENE OVEREXPRESSION; Genes; GENETIC REGULATION; GENETICA; GENETICS; GENETIQUE; MESSENGER RNA; Nuclear Proteins - physiology; Oscillation; Oscillators; Plant Proteins - physiology; PLANTAS TRANSGENICAS; PLANTE TRANSGENIQUE; Plants; PROTEIN SYNTHESIS; PROTEINAS AGLUTINANTES; PROTEINE DE LIAISON; Proteins; RITMOS BIOLOGICOS; RNA; RNA binding proteins; RNA-Binding Proteins - physiology; RYTHME BIOLOGIQUE; SINTESIS DE PROTEINAS; SYNTHESE PROTEIQUE; TRANSGENIC PLANTS
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.94.16.8515

The endogenous clock that drives circadian rhythms is thought to communicate temporal information within the cell via cycling downstream transcripts. A transcript encoding a glycine-rich RNA-binding protein, Atgrp7, in Arabidopsis thaliana undergoes circadian oscillations with peak levels in the evening. The AtGRP7 protein also cycles with a time delay so that Atgrp7 transcript levels decline when the AtGRP7 protein accumulates to high levels. After AtGRP7 protein concentration has fallen to trough levels, Atgrp7 transcript starts to reaccumulate. Overexpression of AtGRP7 in transgenic Arabidopsis plants severely depresses cycling of the endogenous Atgrp7 transcript. These data establish both transcript and protein as components of a negative feedback circuit capable of generating a stable oscillation. AtGRP7 overexpression also depresses the oscillation of the circadian-regulated transcript encoding the related RNA-binding protein AtGRP8 but does not affect the oscillation of transcripts such as cab or catalase mRNAs. We propose that the AtGRP7 autoregulatory loop represents a "slave" oscillator in Arabidopsis that receives temporal information from a central "master" oscillator, conserves the rhythmicity by negative feedback, and transduces it to the output pathway by regulating a subset of clock-controlled transcripts