Sandbox Reserved 310
| This Sandbox is Reserved from January 10, 2010, through April 10, 2011 for use in BCMB 307-Proteins course taught by Andrea Gorrell at the University of Northern British Columbia, Prince George, BC, Canada. |
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| 1x0p, resolution 2.00Å () | |||||||||
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| Resources: | FirstGlance, OCA, RCSB, PDBsum | ||||||||
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IntroductionIntroduction
The proteins containing sensors for blue light using FAD (BLUF) domains are one class of photoreceptor family that utilizes a flavin chromophore[1]. The other two classes include phototropins (LOV) and cryptochromes[2]. The BLUF domain was first discovered in Rhodobacter sphaeroides as the blue light photoreceptor involved in the repression of photosynthesis genes in AppA protein[1][3]. The BLUF domain is known to exist in many bacteria, including cyanobacteria.
One unique photosensing property of BLUF domain is a light induced spectral shift in the flavin absorption spectrum where the wavelength is longer by approximately 10nm[1]. In AppA this shift occurs quickly upon illumination and is slowly reversed upon return to darkness. This spectral shift is not well understood and is not observed in other flavin binding photoreceptors. There have been two proposed models to explain the spectral shift observed in BLUF containing proteins: π-π stacking between the isoalloxazine ring of flavin and the phenol sidechain of a conserved tyrosine residue or protonation and deprotonation of the flavin ring coupled directly or indirectly with the conserved tyrosine residue[4][5]. These two models are based upon the conserved tyrosine residue Tyr9 in the T110078 protein.
The BLUF domain can be divided into two categories: a multidomain protein, such as those found in the AppA, PAC and YcgF proteins of Escherichia coli, and a “short” protein composed of BLUF at the N-terminus[6]. The amino acid sequences for each BLUF domain is unique, thus it is hard to discuss the role of the conserved tyrosine residue. The crystalline structure of the BLUF domain was solved using the “short” BLUF protein T110078 isolated from Thermosynechococcus elongatus BP-1[1]. T. elongatus is a thermophyllic cyanobacteria with an optimum growth temperature near 57°C. Specifically, the T11078 protein is comprised of 143 amino acid residues and binds an oxidized FAD ligand non-covalently[1].
StructureStructure
BLUF domain is [1].
FunctionFunction
ReferencesReferences
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Kita A, Okajima K, Morimoto Y, Ikeuchi M, Miki K. Structure of a cyanobacterial BLUF protein, Tll0078, containing a novel FAD-binding blue light sensor domain. J Mol Biol. 2005 May 27;349(1):1-9. Epub 2005 Apr 9. PMID:15876364 doi:10.1016/j.jmb.2005.03.067
- ↑ van der Horst MA, Hellingwerf KJ. Photoreceptor proteins, "star actors of modern times": a review of the functional dynamics in the structure of representative members of six different photoreceptor families. Acc Chem Res. 2004 Jan;37(1):13-20. PMID:14730990 doi:10.1021/ar020219d
- ↑ Masuda S, Bauer CE. AppA is a blue light photoreceptor that antirepresses photosynthesis gene expression in Rhodobacter sphaeroides. Cell. 2002 Sep 6;110(5):613-23. PMID:12230978
- ↑ Laan W, van der Horst MA, van Stokkum IH, Hellingwerf KJ. Initial characterization of the primary photochemistry of AppA, a blue-light-using flavin adenine dinucleotide-domain containing transcriptional antirepressor protein from Rhodobacter sphaeroides: a key role for reversible intramolecular proton transfer from the flavin adenine dinucleotide chromophore to a conserved tyrosine? Photochem Photobiol. 2003 Sep;78(3):290-7. PMID:14556317
- ↑ Hasegawa K, Masuda S, Ono TA. Spectroscopic analysis of the dark relaxation process of a photocycle in a sensor of blue light using FAD (BLUF) protein Slr1694 of the cyanobacterium Synechocystis sp. PCC6803. Plant Cell Physiol. 2005 Jan;46(1):136-46. Epub 2005 Jan 19. PMID:15659451 doi:10.1093/pcp/pci003
- ↑ Iseki M, Matsunaga S, Murakami A, Ohno K, Shiga K, Yoshida K, Sugai M, Takahashi T, Hori T, Watanabe M. A blue-light-activated adenylyl cyclase mediates photoavoidance in Euglena gracilis. Nature. 2002 Feb 28;415(6875):1047-51. PMID:11875575 doi:10.1038/4151047a