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  Photodynamics of the small BLUF protein BlrB from Rhodobacter sphaeroides

Zirak, P., Penzkofer, A., Schiereis, T., Hegemann, P., Jung, A., & Schlichting, I. (2006). Photodynamics of the small BLUF protein BlrB from Rhodobacter sphaeroides. Journal of Photochemistry and Photobiology B: Biology, 83(3), 180-194. doi:10.1016/j.jphotobiol.2005.12.015.

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Genre: Journal Article
Alternative Title : Photodynamics of the small BLUF protein BlrB from Rhodobacter sphaeroides

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JPhotochemPhotobiolB_83_2006_180.pdf (Any fulltext), 569KB
 
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Zirak, P., Author
Penzkofer, A., Author
Schiereis, T., Author
Hegemann, Peter, Author
Jung, Astrid1, Author           
Schlichting, Ilme1, Author           
Affiliations:
1Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Max Planck Society, ou_1497700              

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Free keywords: BLUF domain, BlrB from Rhodobacter sphaeroides, blue-light photoreceptor, absorption spectroscopy, fluorescence spectroscopy, photocycle, photo-reduction, flavoprotein, flavins, flavin-semiquinone
 Abstract: The BLUF protein BlrB from the non-sulphur anoxyphototrophic purple bacterium Rhodobacter sphaeroides is characterized by absorption and emission spectroscopy. BlrB expressed from E. coli binding FAD, FMN, and riboflavin (called BrlB(I)) and recombinant BlrB containing only FAD (called BlrB(II)) are investigated. The dark-adapted proteins exist in two different receptor conformations (receptor states) with different sub-nanosecond fluorescence lifetimes (BLUF(r,f) and BLUF(r,sl)). Some of the flavin-cofactor (ca. 8%) is unbound in thermodynamic equilibrium with the bound cofactor. The two receptor conformations are transformed to putative signalling states (BLUF(s,f) and BLUF(s,sl)) of decreased fluorescence efficiency and shortened fluorescence lifetime by blue-light excitation. In the dark at room temperature both signalling states recover back to the initial receptor states with a time constant of about 2s. Quantum yields of signalling state formation of about 90% for BlrB(II) and about 40% for BlrB(I) were determined by intensity dependent transmission measurements. Extended blue-light excitation causes unbound flavin degradation (formation of lumichrome and lumiflavin-derivatives) and bound cofactor conversion to the semiquinone form. The flavin-semiquinone further reduces and the reduced flavin re-oxidizes back in the dark. A photo-dynamics scheme is presented and relevant quantum efficiencies and time constants are determined.

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Language(s): eng - English
 Dates: 2005-12-122005-09-252005-12-262006-02-212006-06-01
 Publication Status: Issued
 Pages: 15
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Degree: -

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Title: Journal of Photochemistry and Photobiology B: Biology
  Other : Journal of Photochemistry and Photobiology B: Bio
Source Genre: Journal
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Publ. Info: Lausanne : Elsevier
Pages: - Volume / Issue: 83 (3) Sequence Number: - Start / End Page: 180 - 194 Identifier: ISSN: 1011-1344
CoNE: https://pure.mpg.de/cone/journals/resource/954925584248