ANALYSIS OF THE STRUCTURE OF PSEUDOMONAS-GLUMAE LIPASE

The lipase produced by Pseudomonas glumae is monomeric in the crystall ine state and has a serine protease-like catalytic triad; Ser87-His285 -Asp263. The largest domain of the protein resembles closely a subset of the frequently observed alpha/beta-hydrolase fold and contains a we ll-defined calcium site. This paper describes structural analysis of t his protein, focusing on (i) structural comparison with the lipase fro m Geotrichum candidum, (ii) the probable nature of the conformational change involved in substrate binding and (iii) structural variations a mongst the family of Pseudomonas lipases. This analysis reveals simila rities between P.glumae lipase and G.candidum lipase involving seconda ry structural elements of the hydrolase core and the loops carrying th e catalytic serine and histidine residues. A possible functional equiv alence has also been identified between parts of the two molecules tho ught to be involved in a conformational change. In addition, determina tion of the structure of P.glumae lipase has allowed rationalization o f previously reported protein engineering experiments, which succeeded in improving the stability of the enzyme with respect to proteolysis.