| Time-resolved spectroscopic studies of the AppA blue-light receptor BLUF domain from Rhodobacter sphaeroides. | |
MedLine Citation:
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PMID: 16331957 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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AppA is a blue-light and redox-responding regulator of photosynthesis gene expression in Rhodobacter sphaeroides. Detailed time-resolved fluorescence spectroscopy and subpicosecond transient absorption spectroscopy study of the BLUF domain is presented for wild-type AppA (AppAwt) and a photoinactive Y21F mutant of AppA. The main findings discussed here are that (1) time-resolved laser excitation studies on dark-adapted protein show that AppAwt and Y21F mutant protein exhibits a fluorescence decay with a lifetime of 0.6 ns. Dark-adapted AppAwt but not Y21F also exhibits slower fluorescence decay with a lifetime of 1.7 ns. Analysis of AppAwt that was light-excited to a stable light-adapted form prior to data collection shows monoexponential fluorescence decay with a lifetime of 1.0 ns. This component disappeared after 1 min of data collection after which the original "dark-adapted" values were recovered, demonstrating the presence of a approximately 1 min lifetime intermediate during the return of AppA from light- to dark-adapted form. (2) Transient absorption spectral analysis reveals a very fast rising of transient absorption (<1 ps) for AppAwt. This fast component is missing in the Y21F mutant, which lacks Tyr21, giving rise to a slower transient absorption at 4-6 ps. In the AppAwt transient spectra, most ground states recover within approximately 30 ps, compared to approximately 90-130 ps in the mutant Y21F. We propose that a temporary electron transfer occurs from Tyr21 to the N5 of flavin in AppAwt and is a triggering event for subsequent hydrogen-bond rearrangements. Dynamics of the AppA photocycle is discussed in view of the currently solved crystallographic structure of AppA. |
Authors:
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Vladimira Dragnea; Matthias Waegele; Septimiu Balascuta; Carl Bauer; Bogdan Dragnea |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural |
Journal Detail:
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Title: Biochemistry Volume: 44 ISSN: 0006-2960 ISO Abbreviation: Biochemistry Publication Date: 2005 Dec |
Date Detail:
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Created Date: 2005-12-07 Completed Date: 2006-02-21 Revised Date: 2014-09-22 |
Medline Journal Info:
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Nlm Unique ID: 0370623 Medline TA: Biochemistry Country: United States |
Other Details:
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Languages: eng Pagination: 15978-85 Citation Subset: IM |
| Data Bank Information | |
Bank Name/Acc. No.:
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PDB/1YRX |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Bacterial Proteins
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chemistry*,
genetics,
metabolism Binding Sites Flavoproteins / chemistry*, genetics, metabolism Light Molecular Structure Oxidation-Reduction Photoreceptors, Microbial / chemistry*, genetics, metabolism Rhodobacter sphaeroides / chemistry, metabolism* Spectrometry, Fluorescence Time Factors |
| Grant Support | |
ID/Acronym/Agency:
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GM53940/GM/NIGMS NIH HHS; R01 GM053940/GM/NIGMS NIH HHS; R01 GM053940-04/GM/NIGMS NIH HHS; R01 GM081029-01/GM/NIGMS NIH HHS; R37 GM040941/GM/NIGMS NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/AppA protein, Rhodobacter sphaeroides; 0/Bacterial Proteins; 0/Flavoproteins; 0/Photoreceptors, Microbial |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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