Journal Article

Disordered clock protein interactions and charge blocks turn an hourglass into a persistent circadian oscillator

Holehouse, Alex S., Ginell, Garrett M., Thomas, Joshua, Jankowski, Meaghan S., Pelham, Jacqueline F., Griffith, Daniel, Shastry, Divya G., Karande, Pankaj, Hurley, Jennifer M.

2024

Overview

Organismal physiology is widely regulated by the molecular circadian clock, a feedback loop composed of protein complexes whose members are enriched in intrinsically disordered regions. These regions can mediate protein-protein interactions via SLiMs, but the contribution of these disordered regions to clock protein interactions had not been elucidated. To determine the functionality of these disordered regions, we applied a synthetic peptide microarray approach to the disordered clock protein FRQ in Neurospora crassa . We identified residues required for FRQ’s interaction with its partner protein FRH, the mutation of which demonstrated FRH is necessary for persistent clock oscillations but not repression of transcriptional activity. Additionally, the microarray demonstrated an enrichment of FRH binding to FRQ peptides with a net positive charge. We found that positively charged residues occurred in significant “blocks” within the amino acid sequence of FRQ and that ablation of one of these blocks affected both core clock timing and physiological clock output. Finally, we found positive charge clusters were a commonly shared molecular feature in repressive circadian clock proteins. Overall, our study suggests a mechanistic purpose for positive charge blocks and yielded insights into repressive arm protein roles in clock function. Many clock proteins contain intrinsically disordered regions, but how these regions mediate protein interactions is poorly understood. Here, the authors identify charge blocks within a disordered clock protein that regulate circadian timing.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 13/1 / 13/51 / 38/47 / 38/5 / 38/61 / 631/378/1385/1330 / 631/45/611 / 631/553/2693 / 631/57/2269 / 82/75 / 82/79 / Ablation / Amino Acid Sequence / Amino acids / Biological clocks / Circadian Clocks - genetics / Circadian Clocks - physiology / Circadian rhythm / Circadian Rhythm - genetics / Circadian Rhythm - physiology / Circadian rhythms / CLOCK protein / CLOCK Proteins - chemistry / CLOCK Proteins - genetics / CLOCK Proteins - metabolism / Feedback loops / Fungal Proteins - chemistry / Fungal Proteins - genetics / Fungal Proteins - metabolism / Gene Expression Regulation, Fungal / Gene silencing / Humanities and Social Sciences / Intrinsically Disordered Proteins - chemistry / Intrinsically Disordered Proteins - genetics / Intrinsically Disordered Proteins - metabolism / multidisciplinary / Mutation / Neurospora / Neurospora crassa - genetics / Neurospora crassa - metabolism / Peptides / Physiology / Protein Array Analysis / Protein Binding / Protein interaction / Proteins / Residues / Science / Science (multidisciplinary) / Yeast