Vibrational assignment of the ultrafast infrared spectrum of the photoactivatable flavoprotein AppA

Haigney, Allison, Lukacs, Andras, Brust, Richard, Zhao, Rui, Towrie, Michael, Greetham, Gregory M., Clark, Ian, Illarionov, Boris, Bacher, Adelbert, Kim, Ryu-Ryun, Fischer, Markus, Meech, Stephen R. ORCID: https://orcid.org/0000-0001-5561-2782 and Tonge, Peter J. (2012) Vibrational assignment of the ultrafast infrared spectrum of the photoactivatable flavoprotein AppA. The Journal of Physical Chemistry B, 116 (35). pp. 10722-10729. ISSN 1520-6106

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Abstract

The blue light using flavin (BLUF) domain proteins, such as the transcriptional antirepressor AppA, are a novel class of photosensors that bind flavin noncovalently in order to sense and respond to high-intensity blue (450 nm) light. Importantly, the noncovalently bound flavin chromophore is unable to undergo large-scale structural change upon light absorption, and thus there is significant interest in understanding how the BLUF protein matrix senses and responds to flavin photoexcitation. Light absorption is proposed to result in alterations in the hydrogen-bonding network that surrounds the flavin chromophore on an ultrafast time scale, and the structural changes caused by photoexcitation are being probed by vibrational spectroscopy. Here we report ultrafast time-resolved infrared spectra of the AppA BLUF domain (AppABLUF) reconstituted with isotopes of FAD, specifically [U-13C17]-FAD, [xylene-13C8]-FAD, [U-15N4]-FAD, and [4-18O1]-FAD both in solution and bound to AppABLUF. This allows for unambiguous assignment of ground- and excited-state modes arising directly from the flavin. Studies of model compounds and DFT calculations of the ground-state vibrational spectra reveal the sensitivity of these modes to their environment, indicating they can be used as probes of structural dynamics.

Item Type: Article
Faculty \ School: Faculty of Science > School of Chemistry
Faculty of Science
Depositing User: Pure Connector
Date Deposited: 03 Feb 2014 10:48
Last Modified: 18 Nov 2022 17:30
URI: https://ueaeprints.uea.ac.uk/id/eprint/47473
DOI: 10.1021/jp305220m

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