Localisation of luciferase in luminous marine bacteria by gold immunocytochemical labelling

Abstract Bioluminescent bacteria are able to produce light by an oxidative reaction involving the enzyme luciferase. The biochemistry of the reaction has been well documented. It has been postulated from the reaction pathway that the enzyme luciferase is membrane bound. Two species of luminous bacteria, Vibrio fischeri and V. harveyi , were isolated from sea water, fixed and embedded in resin for transmission electron microscopy. A commercially available V. fischeri bacterial luciferase was used to immunise rats for production of an antibody against luciferase. This antibody was coupled with a protein A gold probe and used to immunolabel the sections of bacteria. It was shown that the luciferase was associated with the inner membrane, and to a lesser extent present in the cytoplasm. Our results confirm that the luciferase is predominantly membrane bound.