12th International Symposium on Bioluminescence & Chemiluminescence

Symposium abstracts:

Substitution of Trp92 by Phe in obelin produces a violet bioluminescence and an increase in the speed of bioluminescence response to calcium

Vysotski, Eugene^1,4, Deng, Lu², Markova, Svetlana^1,4, Blinks, John³, Liu, Zhi-Jie⁴, Herko, Michelle³, Malikova, Natalia¹, Frank, Ludmila¹, Wang, Bi-Cheng⁴, Lee, John⁴

1. Photobiology Lab, Institute of Biophysics RAS, SB, Krasnoyarsk, Russia
2. Department of Chemistry, University of Georgia, USA
^3. Friday Harbor Labs, University of Washington, USA
4. Department of Biochemistry and Molecular Biology, University of Georgia, USA

Mutation of the Trp92 in the active site of obelin from Obelia longissima results in a shift of the bioluminescence color from blue (l _max = 485 nm) to violet due to an additional strong emission with l _max = 410 nm. The 1.72 Å-resolution crystal structure shows an rmsd of only 0.425 Å between WT recombinant obelin and the mutant. There is a displacement of up to 0.6 Å in some residues in the Ca²⁺-binding loops but no significant change in the dimensions of the active site. The violet bioluminescence arises from removal of a hydrogen bond between the Trp92 indole and the p-hydroxyl belonging to the 6-phenyl group of coelenterazine thus favoring emission from the neutral excited state of coelenteramide. The mutation also markedly increases the rate of rise of luminescence after rapid mixing with Ca²⁺ – a potentially useful feature – but in other respects (e.g. Ca²⁺ sensitivity, effects of Mg²⁺, etc) the properties of the mutant are similar to those of wild-type obelin. Supported by ONR, RAS, and NOAA.

This is a preprint of an article accepted for publication in Luminescence: Copyright 2001 John
Wiley & Sons, Ltd (Wiley website)