Open AccessThe clock gene circuit in Arabidopsis includes a repressilator with additional feedback loops
Author(s) -
Pokhilko Alexandra,
Fernández Aurora Piñas,
Edwards Kieron D,
Southern Megan M,
Halliday Karen J,
Millar Andrew J
Publication year - 2012
Publication title -
molecular systems biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 8.523
H-Index - 148
ISSN - 1744-4292
DOI - 10.1038/msb.2012.6
Subject(s) - biology , arabidopsis , positive feedback , physics , gene , computational biology , genetics , electrical engineering , engineering , mutant
Circadian clocks synchronise biological processes with the day/night cycle, using molecular mechanisms that include interlocked, transcriptional feedback loops. Recent experiments identified the evening complex (EC) as a repressor that can be essential for gene expression rhythms in plants. Integrating the EC components in this role significantly alters our mechanistic, mathematical model of the clock gene circuit. Negative autoregulation of the EC genes constitutes the clock's evening loop, replacing the hypothetical component Y . The EC explains our earlier conjecture that the morning gene PSEUDO‐RESPONSE REGULATOR 9 was repressed by an evening gene, previously identified with TIMING OF CAB EXPRESSION1 ( TOC1 ). Our computational analysis suggests that TOC1 is a repressor of the morning genes LATE ELONGATED HYPOCOTYL and CIRCADIAN CLOCK ASSOCIATED1 rather than an activator as first conceived. This removes the necessity for the unknown component X (or TOC1mod) from previous clock models. As well as matching timeseries and phase‐response data, the model provides a new conceptual framework for the plant clock that includes a three‐component repressilator circuit in its complex structure.