Journal Article

PreJuSER-3640

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Time-Resolved Fourier Transform Infrared Study on Photoadduct Formation and Secondary Structural Changes within the Phototropin LOV Domain

Majerus, T.FZJ* ; Kottke, T.FZJ*

2009
Rockefeller Univ. Press New York, NY

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Please use a persistent id in citations: doi:10.1016/j.bpj.2008.11.016

Abstract: 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.

Keyword(s): Arabidopsis: chemistry (MeSH) ; Arabidopsis Proteins (MeSH) ; Cryptochromes (MeSH) ; Cysteine: chemistry (MeSH) ; Flavoproteins: chemistry (MeSH) ; Flavoproteins: genetics (MeSH) ; Kinetics (MeSH) ; Lasers (MeSH) ; Light (MeSH) ; Models, Molecular (MeSH) ; Mutation (MeSH) ; Protein Structure, Secondary (MeSH) ; Protein Structure, Tertiary (MeSH) ; Spectroscopy, Fourier Transform Infrared (MeSH) ; Arabidopsis Proteins ; CRY1 protein, Arabidopsis ; Cryptochromes ; Flavoproteins ; Cysteine ; J

Note: This work was Supported by the Helmholtz Genicinschaft (grant VHNG-014) and Deutsche Forschungsgemeinschaft (grant FOR 526).

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Contributing Institute(s):

1. Molekulare Biophysik (ISB-2)

Research Program(s):

1. ohne FE (ohne FE)

Appears in the scientific report 2009

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