A HAD family phosphatase CSP-6 regulates the circadian output pathway in Neurospora crassa

• Published in: PLoS genetics 2018-01, Vol.14 (1), p.e1007192-e1007192
• Main Authors: Zhou, Xiaoying, Wang, Bin, Emerson, Jillian M, Ringelberg, Carol S, Gerber, Scott A, Loros, Jennifer J, Dunlap, Jay C
• Format: Article
• Language: English
• Subjects: Biochemistry; Biology; Biology and Life Sciences; Circadian Clocks - genetics; Circadian rhythm; Circadian Rhythm - genetics; Circadian rhythms; Deletion mutant; Dephosphorylation; Diurnal; DNA binding proteins; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; DNA-Binding Proteins - physiology; Environmental changes; Feedback; Funding; Fungal Proteins - genetics; Fungal Proteins - metabolism; Fungal Proteins - physiology; Gene expression; Gene Expression Regulation, Fungal; Gene regulation; Hydrolases - genetics; Hydrolases - physiology; Kinases; Localization; Medicine; Neurospora; Neurospora crassa; Neurospora crassa - enzymology; Neurospora crassa - genetics; Observations; Organisms, Genetically Modified; Phosphatase; Phosphatases; Phosphoric Monoester Hydrolases - physiology; Phosphorylation; Physical Sciences; Physiological aspects; Post-translation; Protein Binding; Proteins; Signal Transduction - genetics; Transcription activation; Transcription factors; Transcription Factors - genetics; Transcription Factors - metabolism; Transcription Factors - physiology; Translation
• ISSN: 1553-7404; 1553-7390; 1553-7404
• DOI: 10.1371/journal.pgen.1007192

Circadian clocks are ubiquitous in eukaryotic organisms where they are used to anticipate regularly occurring diurnal and seasonal environmental changes. Nevertheless, little is known regarding pathways connecting the core clock to its output pathways. Here, we report that the HAD family phosphatase CSP-6 is required for overt circadian clock output but not for the core oscillation. The loss of function Δcsp-6 deletion mutant is overtly arrhythmic on race tubes under free running conditions; however, reporter assays confirm that the FREQUENCY-WHITE COLLAR COMPLEX core circadian oscillator is functional, indicating a discrete block between oscillator and output. CSP-6 physically interacts with WHI-2, Δwhi-2 mutant phenotypes resemble Δcsp-6, and the CSP-6/WHI-2 complex physically interacts with WC-1, all suggesting that WC-1 is a direct target for CSP-6/WHI-2-mediated dephosphorylation and consistent with observed WC-1 hyperphosphorylation in Δcsp-6. To identify the source of the block to output, known clock-controlled transcription factors were screened for rhythmicity in Δcsp-6, identifying loss of circadian control of ADV-1, a direct target of WC-1, as responsible for the loss of overt rhythmicity. The CSP-6/WHI-2 complex thus participates in the clock output pathway by regulating WC-1 phosphorylation to promote proper transcriptional/translational activation of adv-1/ADV-1; these data establish an unexpected essential role for post-translational modification parallel to circadian transcriptional regulation in the early steps of circadian output.