A Global Circadian Repressor Controls Antiphasic Expression of Metabolic Genes in Neurospora

Molecular Cell, Год журнала: 2011, Номер 44(5), С. 687 - 697

Опубликована: Дек. 1, 2011

The white-collar complex (WCC), the core transcription factor of circadian clock Neurospora, activates morning-specific expression repressor CSP1. Newly synthesized CSP1 exists in a transient with corepressor RCM1/RCO1 and ubiquitin ligase UBR1. is rapidly hyperphosphorylated degraded via UBR1 its conjugase RAD6. Genes controlled by are rhythmically expressed peak evening (i.e., antiphase to genes directly WCC). Rhythmic these second-tier depends crucially on phosphorylation rapid turnover CSP1, which ensures tight coupling abundance function activity WCC. Negative feedback own buffers amplitude CSP1-dependent oscillations against fluctuations WCC activity. predominantly regulates involved metabolism. It controls ergosterol synthesis fatty acid desaturases thereby modulates lipid composition membranes.

Язык: Английский

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Light-Induced Subunit Dissociation by a Light–Oxygen–Voltage Domain Photoreceptor from Rhodobacter sphaeroides

Biochemistry, Год журнала: 2012, Номер 52(2), С. 378 - 391

Опубликована: Дек. 19, 2012

Light–oxygen–voltage (LOV) domains bind a flavin chromophore to serve as blue light sensors in wide range of eukaryotic and prokaryotic proteins. LOV are associated with variable effector domain or separate protein signaling partner execute variety functions that include regulation kinases, generation anti-sigma factor antagonists, circadian clocks. Here we present the crystal structure, photocycle kinetics, association properties, spectroscopic features full-length from Rhodobacter sphaeroides (RsLOV). RsLOV exhibits N- C-terminal helical extensions form an unusual bundle at its dimer interface some resemblance transducer sensory rhodopsin II. The light-induced conformational changes revealed comparison light- dark-state structures support shared mechanism proteins originates formation flavin–cysteinyl photoadduct. Adduct disrupts hydrogen bonding active site propagates structural through core extensions. Single-residue variants alter photoadduct lifetimes induce perturb oligomeric state. Size exclusion chromatography, multiangle scattering, small-angle X-ray cross-linking studies indicate dimerizes dark but, upon excitation, dissociates into monomers. This switch state may prove be useful for engineering molecular associations controlled cellular settings.

Язык: Английский

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Neurospora WC-1 Recruits SWI/SNF to Remodel frequency and Initiate a Circadian Cycle

PLoS Genetics, Год журнала: 2014, Номер 10(9), С. e1004599 - e1004599

Опубликована: Сен. 25, 2014

In the negative feedback loop comprising Neurospora circadian oscillator, White Collar Complex (WCC) formed from Collar-1 (WC-1) and Collar-2 (WC-2) drives transcription of pacemaker gene frequency (frq). Although FRQ-dependent repression WCC has been extensively studied, mechanism by which initiates a cycle remains elusive. Structure/function analysis WC-1 eliminated domains previously thought to transactivate frq expression but instead identified amino acids 100–200 as essential for expression. A proteomics-based search coactivators with uncovered SWI/SNF (SWItch/Sucrose NonFermentable) complex: interacts in vivo vitro, binds Clock box promoter, is required both remodeling nucleosomes at rhythmic expression; interestingly, not light-induced These data suggest model recruits remodel chromatin frq, thereby activating initiate cycle.

Язык: Английский

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Circadian oscillator proteins across the kingdoms of life: structural aspects

BMC Biology, Год журнала: 2019, Номер 17(1)

Опубликована: Фев. 18, 2019

Circadian oscillators are networks of biochemical feedback loops that generate 24-hour rhythms in organisms from bacteria to animals. These periodic result a complex interplay among clock components specific the organism, but share molecular mechanisms across kingdoms. A full understanding these processes requires detailed knowledge, not only properties proteins and their interactions, also three-dimensional structure clockwork components. Posttranslational modifications protein–protein interactions have become recent focus, particular mediated by phosphorylation formation multimeric protein complexes regulate genes at transcriptional translational levels. This review covers structural aspects circadian oscillators, serves as primer for this exciting realm biology.

Язык: Английский

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Engineering AraC to make it responsive to light instead of arabinose

Nature Chemical Biology, Год журнала: 2021, Номер 17(7), С. 817 - 827

Опубликована: Апрель 26, 2021

Язык: Английский

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