title: Isolation of Erwinia chrysanthemi kduD mutants altered in pectin degradation.
abstract: Mutants of Erwinia chrysanthemi impaired in pectin degradation were isolated by chemical and Mu d(Ap lac) insertion mutagenesis. A mutation in the kduD gene coding for 2-keto-3-deoxygluconate oxidoreductase prevented the growth of the bacteria on polygalacturonate as the sole carbon source. Analysis of the kduD::Mu d(Ap lac) insertions indicated that kduD is either an isolated gene or the last gene of a polycistronic operon. Some of the Mu d(Ap lac) insertions were kduD-lac fusions in which beta-galactosidase synthesis reflected kduD gene expression. In all these fusions, beta-galactosidase activity was shown to be sensitive to catabolite repression by glucose and to be inducible by polygalacturonate, galacturonate, and other intermediates of polygalacturonate catabolism. Galacturonate-mediated induction was prevented by a mutation which blocked its metabolism to 2-keto-3-deoxygluconate. 2-Keto-3-deoxygluconate appeared to be the true inducer of kduD expression resulting from galacturonate degradation. 5-Keto-4-deoxyuronate or 2,5-diketo-3-deoxygluconate were the true inducers, originating from polygalacturonate cleavage. These three intermediates also appeared to induce pectate lyases, oligogalacturonate lyase, and 5-keto-4-deoxyuronate isomerase synthesis.
mesh_terms: D019747:Aldose-Ketose Isomerases; D001426:Bacterial Proteins; D002238:Carbohydrate Epimerases / Q000096:biosynthesis; D004790:Enzyme Induction; D004794:Enzyme Repression; D004885:Erwinia / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D005798:Genes, Bacterial; D005942:Gluconates / Q000378:metabolism; D009154:Mutation; D010368:Pectins / Q000378:metabolism*; D011133:Polysaccharide-Lyases / Q000096:biosynthesis; D013401:Sugar Alcohol Dehydrogenases / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D005942:Gluconates; C002957:2-keto-3-deoxygluconate; D010368:Pectins; D013401:Sugar Alcohol Dehydrogenases; C045226:3-deoxy-D-glycero-2,5-hexodiulosonate dehydrogenase; D011133:Polysaccharide-Lyases; C045225:oligogalacturonate lyase; C023911:pectate lyase; D002238:Carbohydrate Epimerases; D019747:Aldose-Ketose Isomerases; C048091:4-deoxy-L-threo-5-hexosulose-uronate ketol-isomerase; C003181:polygalacturonic acid