title: Isolation and characterization of Tn5 insertion mutants of Erwinia chrysanthemi that are deficient in polygalacturonate catabolic enzymes oligogalacturonate lyase and 3-deoxy-D-glycero-2,5-hexodiulosonate dehydrogenase.
abstract: Mutants of Erwinia chrysanthemi EC16 deficient in the polygalacturonate catabolic enzymes oligogalacturonate lyase (Ogl-) and 3-deoxy-D-glycero-2,5-hexodiulosonate (ketodeoxyuronate) dehydrogenase (KduD-) were obtained by Tn5 mutagenesis using the R plasmid pJB4JI. Ogl- Exu+ (Exu+, D-galacturonate utilization) and KduD- Exu- strains macerated potato tuber tissue and utilized glucose, glycerol, and gluconate, but they did not utilize polygalacturonate, unsaturated digalacturonate, or saturated digalacturonate. Genetic and physical evidence indicated that the Ogl- mutants and a KduD- recombinant contained a single copy of Tn5 and that Tn5 (Kmr) was linked to the mutant phenotypes. In the Ogl+ parents, basal levels of oligogalacturonate lyase were present in glycerol-grown cells and induced levels were present with saturated or unsaturated digalacturonate, while oligogalacturonate lyase was undetectable under similar conditions in Ogl- strains. Pectate lyase, polygalacturonase, and ketodeoxyuronate dehydrogenase were induced in an Ogl- strain by 3-deoxy-D-glycero-2,5-hexodiulosonate and by the enzymatic products of unsaturated digalacturonate but not by the digalacturonates. The KduD- strains lacked the dehydrogenase activity but in the presence of the digalacturonates produced higher levels of pectate lyase, polygalacturonase, and oligogalacturonate lyase than the KduD+ parents did. In the KduD- strains, pectate lyase and oligogalacturonate lyase were induced by unsaturated digalacturonate in a "gratuitous" manner, suggesting an intracellular accumulation of the inducer(s). We conclude that an intermediate(s) of the ketodeoxyuronate pathway induces pectate lyase, polygalacturonase, oligogalacturonate lyase, and ketodeoxyuronate dehydrogenase in E. chrysanthemi.
authors.forename: A K
authors.initials: AK
authors.lastname: Chatterjee
authors.forename: K K
authors.initials: KK
authors.lastname: Thurn
authors.forename: D J
authors.initials: DJ
authors.lastname: Tyrell
mesh_terms: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004351:Drug Resistance; D004885:Erwinia / Q000201:enzymology / Q000235:genetics*; D008040:Genetic Linkage; D007612:Kanamycin / Q000633:toxicity; D010368:Pectins / Q000096:biosynthesis*; D011133:Polysaccharide-Lyases / Q000172:deficiency / Q000235:genetics*; D013401:Sugar Alcohol Dehydrogenases / Q000172:deficiency / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D007612:Kanamycin; D010368:Pectins; D013401:Sugar Alcohol Dehydrogenases; C045226:3-deoxy-D-glycero-2,5-hexodiulosonate dehydrogenase; D011133:Polysaccharide-Lyases; C045225:oligogalacturonate lyase