Team:Edinburgh/Bacterial/Blue light producer
Overview: The blue light producer
To produce blue light, we used two systems using the bacterial luciferase from Xenorhabdus luminescens (LuxAB). The standalone LuxAB has an emission peak of 495nm (Figure 1). According to O'Kane and Lee (1985) and others, the addition of lumazine protein LumP shifts the wavelength towards the blue spectrum (478 nm), such that it will be in the correct region to activate the blue light sensor.
Figure 1: Emission spectra of LuxAB (in solid black line). The LuxAB depicted is that from Vibrio campbellii, but sources confirm that other bacterial luciferases produce similar spectral graphs.
Image: Suadee et al. (2008)
Last year's Edinburgh team already made both of these parts individually, so all we had to do was fuse them together and add a promoter. Individual parts were resubmitted in pSB1C3.
We were experiencing problems with last year’s LuxAB and LumP parts, in that blue and red colonies were growing when they should not be. This was another reason for resubmitting them, as the parts contained in the Registry may have the same problems.
We have also had issues with the instrument used to measure the spectral output. It could not pick up a signal from the tubes despite visible bioluminescence. Hopefully we will be able to characterise these parts more fully before the Jamboree.
Both lumP and luxAB have already been submitted as BioBricks in pSB1A3 by last year's Edinburgh team, but we are re-submitting corrected variants in pSB1C3.
We are also submitting a luxAB-lumP fusion construct in pSB1C3 with a constitutive promoter which can be used for blue light production. We have confirmation of working luxAB with the promoter in question.
BBa_K322140: luxAB under lac promoter.
BBa_K322141: luxAB and luxCDE under lac promoter.
BBa_K322149: luxAB and lumP composite part.
BBa_K322150: luxAB and lumP under lac promoter.
Figure 2: Emission output (blue light) of the luxAB/lumP fusion.
Figure 2 shows the light output of the luxAB/lumP fusion, a distinctly blue colour. Unfortunately, we have been unable so far to get a spectrum reading from our samples, but hope to be able to achieve one by the Jamboree.
O'Kane, D. J. & Lee, J. (1985). Chemical characterization of lumazine protein from Photobacterium leiognathi: comparison with lumazine protein from Photobacterium phosphoreum. Biochemistry 24, 1467-1475.
Suadee, C., Nijvipakul, S., et al. (2008). LuxG Is a Functioning Flavin Reductase for Bacterial Luminescence. J. Bacteriol. 190(5): 1531-1538
Edinburgh 2009 team wiki, http://2009.igem.org/Team:Edinburgh.