TY  - JOUR
AU  - Majerus, T.
AU  - Kottke, T.
TI  - Time-Resolved Fourier Transform Infrared Study on Photoadduct Formation and Secondary Structural Changes within the Phototropin LOV Domain
JO  - Biophysical journal
VL  - 96
SN  - 0006-3495
CY  - New York, NY
PB  - Rockefeller Univ. Press
M1  - PreJuSER-3640
SP  - 1462 - 1470
PY  - 2009
N1  - This work was Supported by the Helmholtz Genicinschaft (grant VHNG-014) and Deutsche Forschungsgemeinschaft (grant FOR 526).
AB  - Phototropins are plant blue-light photoreceptors containing two light-, oxygen-, or voltage-sensitive (LOV) domains and a C-terminal kinase domain. The two LOV domains bind noncovalently flavin mononucleotide as a chromophore. We investigated the photocycle of fast-recovery mutant LOV2-I403V from Arabidopsis phototropin 2 by step-scan Fourier transform infrared spectroscopy. The reaction of the triplet excited state of flavin with cysteine takes place with a time constant of 3 micros to yield the covalent adduct. Our data provide evidence that the flavin is unprotonated in the productive triplet state, disfavoring an ionic mechanism of bond formation. An intermediate adduct species was evident that displayed changes in secondary structure in the helix or loop region, and relaxed with a time constant of 120 micros. In milliseconds, the final adduct state is formed by further alterations of secondary structure, including beta-sheets. A comparison with wild-type adduct spectra shows that the mutation does not interfere with the functionality of the domain. All signals originate from within the LOV domain, because the construct does not comprise the adjacent Jalpha helix required for signal transduction. The contribution of early and late adduct intermediates to signal transfer to the Jalpha helix outside of the domain is discussed.
KW  - Arabidopsis: chemistry
KW  - Arabidopsis Proteins
KW  - Cryptochromes
KW  - Cysteine: chemistry
KW  - Flavoproteins: chemistry
KW  - Flavoproteins: genetics
KW  - Kinetics
KW  - Lasers
KW  - Light
KW  - Models, Molecular
KW  - Mutation
KW  - Protein Structure, Secondary
KW  - Protein Structure, Tertiary
KW  - Spectroscopy, Fourier Transform Infrared
KW  - Arabidopsis Proteins (NLM Chemicals)
KW  - CRY1 protein, Arabidopsis (NLM Chemicals)
KW  - Cryptochromes (NLM Chemicals)
KW  - Flavoproteins (NLM Chemicals)
KW  - Cysteine (NLM Chemicals)
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
C6  - pmid:19217862
C2  - pmc:PMC2717236
UR  - <Go to ISI:>//WOS:000266377800021
DO  - DOI:10.1016/j.bpj.2008.11.016
UR  - https://juser.fz-juelich.de/record/3640
ER  -