Identification of a seventh endo-pectate lyase of the phytopathogenic bacterium Erwinia chrysanthemi

Abstract

Abstract The Erwinia genus includes soil bacteria with saprophytic or phytopathogenic ways of life. The species E. chrysanthemi is the causal agent of soft-rot disease. The E. chrysanthemi strain 3937 produces five major and several secondary endo-pectate lyases. The independent encoding genes are arranged in three clusters: pelA-pelE-pelD, pelB-pelC and pelL. Recently, molecular studies of the genomic region surrounding the pelB-pelC cluster have led to the identification of a new pectinase gene named pelZ. The PelZ protein is an enzyme with a weak endo-pectate lyase activity that generates mainly unsaturated trigalacturonate. Its activity requires the presence of Ca2+ or Mn2+, a basic pH and the activity decreases when the degree of pectin methylation increases. The pelZ gene exists in different strains of Erwinia and its expression is subjected to many different regulations.