Document Detail


Time-resolved spectroscopic studies of the AppA blue-light receptor BLUF domain from Rhodobacter sphaeroides.
MedLine Citation:
PMID:  16331957     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
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:
Vladimira Dragnea; Matthias Waegele; Septimiu Balascuta; Carl Bauer; Bogdan Dragnea
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural    
Journal Detail:
Title:  Biochemistry     Volume:  44     ISSN:  0006-2960     ISO Abbreviation:  Biochemistry     Publication Date:  2005 Dec 
Date Detail:
Created Date:  2005-12-07     Completed Date:  2006-02-21     Revised Date:  2014-09-22    
Medline Journal Info:
Nlm Unique ID:  0370623     Medline TA:  Biochemistry     Country:  United States    
Other Details:
Languages:  eng     Pagination:  15978-85     Citation Subset:  IM    
Data Bank Information
Bank Name/Acc. No.:
PDB/1YRX
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MeSH Terms
Descriptor/Qualifier:
Bacterial Proteins / 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:
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:
0/AppA protein, Rhodobacter sphaeroides; 0/Bacterial Proteins; 0/Flavoproteins; 0/Photoreceptors, Microbial
Comments/Corrections

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