Ester biosynthesis and metabolism

Science programme: Molecular olfaction

Esters are an important family of volatile compounds produced by many organisms as signalling compounds.  In plants, for example, esters are often major components of the aroma produced by fruit to attract seed dispersers.  Many sex pheromones produced by insects are also esters.  We are interested in the enzymes involved in the biosynthesis and metabolism of esters and their potential use in industrial biotechnology and plant breeding.

The final step in ester biosynthesis involves the production of esters from acids and alcohols.  We have characterised some acyl transferases from fruit that participate in the production of esters from apple (Souleyre et al., 2005). By over expression of these acyl transferases in surrogate cell systems these enzymes can be purified and characterised kinetically. These and other genes involved in the biosynthesis of aroma compounds are up-regulated during fruit ripening. These enzymes would be used for applications in Industrial biotechnology  to bioferment flavours and fragrances.

Esterases likely perform the opposite reaction to acyl transferases, hydrolysing esters.  We have described a new family of carboxylesterases in plants (Marshall et al., 2003) and shown that they can hydrolyse a wide range of esters commonly found in plants.  In collaboration with The Structural Biology Group at Auckland University we have solved the 3D structure of one of these plant carboxylesterases revealing they are members of the a/b hydrolase fold superfamily of proteins (See poster Structure of a plant carboxylesterase, ActCXE1 from kiwifruit ).

Contact Richard Newcomb