title: Structural basis for the emission of violet bioluminescence from a W92F obelin mutant.
abstract: Mutation of the Trp92 that is known to lie within the active site of the photoprotein obelin from Obelia longissima, results in a shift of the bioluminescence color from blue (lambda(max)=485 nm) to violet. The corrected spectrum shows a new band with lambda(max)=410 nm now contributing equally to the one at longer wavelength. The crystal structure of this W92F obelin determined at 1.72 A resolution shows that there is no significant change in the dimensions of the active site between WT obelin (recombinant Ca2+-regulated photoprotein from Obelia longissima) and the mutant. It is proposed that the bioluminescence spectral shift results from removal of a hydrogen bond from the indole of W92 nearby a hydroxyl belonging to the 6-phenyl substituent of the substrate coelenterazine. Propagation of this change through a conjugated bond system in the excited state of the product coelenteramide affects the coupling of the N1-position and the hydrogen-bonded Y138.
authors.affiliation: Department of Chemistry, University of Georgia, Athens 30602, USA. ldeng@sunchem.chem.uga.edu
authors.forename: L
authors.initials: L
authors.lastname: Deng
authors.forename: E S
authors.initials: ES
authors.lastname: Vysotski
authors.forename: Z J
authors.initials: ZJ
authors.lastname: Liu
authors.forename: S V
authors.initials: SV
authors.lastname: Markova
authors.forename: N P
authors.initials: NP
authors.lastname: Malikova
authors.forename: J
authors.initials: J
authors.lastname: Lee
authors.forename: J
authors.initials: J
authors.lastname: Rose
authors.forename: B C
authors.initials: BC
authors.lastname: Wang
mesh_terms: D001483:Base Sequence; D017931:DNA Primers; D049449:Luminescence; D008164:Luminescent Proteins / Q000737:chemistry* / Q000235:genetics; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence
chemical_list: D017931:DNA Primers; D008164:Luminescent Proteins; C010497:obelin