BROAD ALDEHYDE SPECIFICITY, INCLUDING TOMATO ALDEHYDES, BY RECOMBINANT LUCIFERASE FROM PHOTOBACTERIUM

Bacterial luciferase (Lux) is a light producing flavoenzyme encoded by the luxA and luxB genes of the six gene lux operon of Photobacterium fischeri and Vibrio harveyi. Luciferase produces light by the oxidatio n of aldehyde in the presence of reduced flavin and oxygen. A simple a nd highly sensitive bioassay, employing a recombinant fusion protein c omprised of LuxA and LuxB subunits containing an 81 base pair spacer s equence for optimum activity in Escherichia coli was used to measure t he effects of different aldehydes as substrates for the recombinant lu ciferase activity. We examined a range of aliphatic aldehydes, and fou nd that the recombinant luciferase utilizes any linear aliphatic aldeh yde from 1 to 12 carbons in length, including several branched forms. The recombinant luciferase exhibited increased efficiency of substrate binding and product formation with increasing aldehyde length. Natura lly occurring endogenous aldehydes in tomato plants measured by our bi oassay system, demonstrated that the concentrations of aldehyde are or gan specific and reflect the stage of development. The tomato fruit wa s found to accumulate free aldehydes as it ripens, confirming previous chemical analyses on ripening fruits.