Proteins in Action: Femtosecond to Millisecond Structural Dynamics of a Photoactive Flavoprotein

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• 作者：Richard Brust ; Andras Lukacs ; Allison Haigney ; Kiri Addison ; Agnieszka Gil ; Michael Towrie ; Ian P. Clark ; Gregory M. Greetham ; Peter J. Tonge ; Stephen R. Meech
• 刊名：Journal of the American Chemical Society
• 出版年：2013
• 出版时间：October 30, 2013
• 年：2013
• 卷：135
• 期：43
• 页码：16168-16174
• 全文大小：371K
• 年卷期：v.135,no.43(October 30, 2013)
• ISSN：1520-5126

文摘

Living systems are fundamentally dependent on the ability of proteins to respond to external stimuli. The mechanism, the underlying structural dynamics, and the time scales for regulation of this response are central questions in biochemistry. Here we probe the structural dynamics of the BLUF domain found in several photoactive flavoproteins, which is responsible for light activated functions as diverse as phototaxis and gene regulation. Measurements have been made over 10 decades of time (from 100 fs to 1 ms) using transient vibrational spectroscopy. Chromophore (flavin ring) localized dynamics occur on the pico- to nanosecond time scale, while subsequent protein structural reorganization is observed over microseconds. Multiple time scales are observed for the dynamics associated with different vibrations of the protein, suggesting an underlying hierarchical relaxation pathway. Structural evolution in residues directly H-bonded to the chromophore takes place more slowly than changes in more remote residues. However, a point mutation which suppresses biological function is shown to 鈥榮hort circuit鈥?this structural relaxation pathway, suppressing the changes which occur further away from the chromophore while accelerating dynamics close to it.