Kinetic Properties of α
-Galactosidase and the Localization of Total Proteins in Erwinia chrysanthemi

Abstract

Erwinia chrysanthemi is an enterobacterium that causes soft-rot in plants in general, resulting in enormous economic losses annually. For the pathogen to survive in the host plant, it has to use the readily assimilable compounds from the host fluids and degrade the host tissue. To accomplish this, E. chrysanthemi produces several extracellular and intracellular enzymes. Among the intracellular enzymes there is a special digestive class, the galactosidases, which can be either periplasmic or cytoplasmic.
α-Galactosidase is known to degrade melibiose and raffinose into glucose and galactose, and into galactose and sucrose respectively. The aim of the present study was to investigate the kinetic properties of α
-galactosidase in E. chrysanthemi, and the localization of total proteins, after culturing it in the presence of raffinose and melibiose. The α
-galactosidase that degrades melibiose seems to be the same enzyme that is also responsible for the breakdown of raffinose in E. chrysanthemi. It is localized mainly in the cytoplasm with a fraction of between 2.4 and 5.4 % localized in the periplasm. The majority of E. chrysanthemi proteins have cytoplasmic localization.

Keywords

• Erwinia chrysanthemi
• α
  -galactosidase
• periplasm
• melibiose
• raffinose