Isoform switching facilitates period control in the Neurospora crassa circadian clock.
A striking and defining feature of circadian clocks is the small variation in period over a physiological range of temperatures. This is referred to as temperature compensation, although recent work has suggested that the variation observed is a specific, adaptive control of period. Moreover, given that many biological rate constants have a Q(10) of around 2, it is remarkable that such clocks remain rhythmic under significant temperature changes. We introduce a new mathematical model for the Neurospora crassa circadian network incorporating experimental work showing that temperature alters the balance of translation between a short and long form of the FREQUENCY (FRQ) protein. This is used to discuss period control and functionality for the Neurospora system. The model reproduces a broad range of key experimental data on temperature dependence and rhythmicity, both in wild-type and mutant strains. We present a simple mechanism utilising the presence of the FRQ isoforms (isoform switching) by which period control could have evolved, and argue that this regulatory structure may also increase the temperature range where the clock is robustly rhythmic.
Akman
Ozgur E
OE
Centre for Systems Biology at Edinburgh, The University of Edinburgh, Edinburgh, UK [corrected]
Locke
James C W
JC
Tang
Sanyi
S
Carré
Isabelle
I
Millar
Andrew J
AJ
Rand
David A
DA
D000483:Alleles; D001683:Biological Clocks / Q000235:genetics / Q000502:physiology*; D002940:Circadian Rhythm / Q000235:genetics / Q000502:physiology*; D019295:Computational Biology / Q000379:methods; D003198:Computer Simulation; D005246:Feedback; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005800:Genes, Fungal; D007700:Kinetics; D015233:Models, Statistical; D009154:Mutation; D009492:Neurospora crassa / Q000235:genetics / Q000502:physiology*; D010766:Phosphorylation; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D011506:Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012984:Software; D013696:Temperature; D014158:Transcription, Genetic
C087405:FRQ protein, Neurospora crassa; D005656:Fungal Proteins; D020033:Protein Isoforms; D011506:Proteins; D012333:RNA, Messenger