Heterogeneous and Highly Dynamic Interface in Plastocyanin-Cytochrome f Complex Revealed by Site-Specific 2D-IR Spectroscopy
Autor: | Jonathan T Specker, Rachel E. Horness, Katherine E. Thibodeau, Amanda L. Le Sueur, Jessica A Collins, Megan C. Thielges, Sashary Ramos |
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Rok vydání: | 2020 |
Předmět: |
Infrared
Infrared spectroscopy Plasma protein binding 010402 general chemistry 01 natural sciences Redox Article 0103 physical sciences Nitriles Spectroscopy Fourier Transform Infrared Materials Chemistry Physical and Theoretical Chemistry Binding site Spectroscopy Nostoc Plastocyanin Cytochrome f Alanine Binding Sites 010304 chemical physics Chemistry 0104 chemical sciences Surfaces Coatings and Films Cytochromes f Molecular Probes Biophysics Hydrophobic and Hydrophilic Interactions Protein Binding |
Zdroj: | The journal of physical chemistry. B. 123(9) |
ISSN: | 1520-5207 |
Popis: | Transient protein complexes are crucial for sustaining dynamic cellular processes. The complexes of electron-transfer proteins are a notable example, such as those formed by plastocyanin (Pc) and cytochrome f (cyt f) in the photosynthetic apparatus. The dynamic and heterogeneous nature of these complexes, however, makes their study challenging. To better elucidate the complex of Nostoc Pc and cyt f, 2D-IR spectroscopy coupled to site-specific labeling with cyanophenylalanine infrared (IR) probes was employed to characterize how the local environments at sites along the surface of Pc were impacted by cyt f binding. The results indicate that Pc most substantially engages with cyt f via the hydrophobic patch around the copper redox site. Complexation with cyt f led to an increase in inhomogeneous broadening of the probe absorptions, reflective of increased heterogeneity of interactions with their environment. Notably, most of the underlying states interconverted very rapidly (1 to 2 ps), suggesting a complex with a highly mobile interface. The data support a model of the complex consisting of a large population of an encounter complex. Additionally, the study demonstrates the application of 2D-IR spectroscopy with site-specifically introduced probes to reveal new quantitative insight about dynamic biochemical systems. |
Databáze: | OpenAIRE |
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