Levansucrases of Pseudomonas bacteria: novel approaches for protein expression, assay of enzymes, fructooligosaccharides and heterooligofructans

Levansucrases are bacterial extracellular enzymes that act on sucrose producing b-2,6-linked fructans of varied chain length. We summarize here our up-to-date results on (i) novel methods for the production of heterologous levansucrase proteins in Escherichia coli, (ii) biochemical characterization of the levansucrases encoded in the genome of a tomato and Arabidopsis pathogen Pseudomonas syringae pv. tomato DC3000, (iii) innovative chipbased mass spectrometric analysis of oligosaccharidic reaction products, (iv) isolation and characterization of the first mutants and structure-function analysis of a levansucrase of P. syringae pv. tomato. Data on the levansucrase LscA of P. chlororaphis subsp. aurantiaca will be presented for comparison. As most important features of the levansucrases from Pseudomonas bacteria we emphasize their ability to synthesize potentially prebiotic fructooligosaccharides from sucrose or raffinose and to transfructosylate a variety of alternative acceptor sugars with production of heterooligofructans.