Regulatory Switching by Concerted Motions on the Microsecond Time Scale of the Oxygen Sensor Protein FixL
| Autor: | Takeo Yamawaki, Yasuhisa Mizutani, Misao Mizuno, Kazuhiro Takemura, Akio Kitao, Yoshitsugu Shiro, Haruto Ishikawa |
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| Rok vydání: | 2021 |
| Předmět: |
Conformational change
Hemeprotein 010304 chemical physics Chemistry Effector Allosteric regulation 010402 general chemistry 01 natural sciences 0104 chemical sciences Surfaces Coatings and Films chemistry.chemical_compound 0103 physical sciences Materials Chemistry Biophysics Phosphorylation sense organs Physical and Theoretical Chemistry Kinase activity Signal transduction skin and connective tissue diseases Heme |
| Zdroj: | The Journal of Physical Chemistry B. 125:6847-6856 |
| ISSN: | 1520-5207 1520-6106 |
| Popis: | Signal transduction proteins perceive external stimuli in their sensor module and regulate the biological activities of the effector module, allowing cellular adaptation in response to environmental changes. FixL is a dimeric heme protein kinase that senses the oxygen level in plant root nodules to regulate the transcription of nitrogen fixation genes via the phosphorylation of its cognate transcriptional activator. Dissociation of oxygen from the heme induces conformational changes in the protein, converting it from the inactive form for phosphorylation to the active form. However, how FixL undergoes conformational change to regulate kinase activity upon oxygen dissociation remains poorly understood. Here we report time-resolved ultraviolet resonance Raman spectra showing conformational changes for FixL from Sinorhizobium meliloti. We observed spectral changes with a time constant of about 3 μs, which were oxygen-specific. Furthermore, we found that the conformational changes in the sensor and kinase domains are coupled, enabling allosteric control of kinase activity. Our results demonstrate that concerted structural changes on the microsecond time scale serve as the regulatory switch in FixL. |
| Databáze: | OpenAIRE |
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