Showing papers by "Janet L. Schottel published in 1994"

CDP-6-deoxy-delta 3,4-glucoseen reductase from Yersinia pseudotuberculosis: enzyme purification and characterization of the cloned gene.

Abstract: The 3,6-dideoxyhexoses, usually confined to the cell wall lipopolysaccharide of gram-negative bacteria, are essential to serological specificity and are formed via a complex biosynthetic pathway beginning with CDP-D-hexoses. In particular, the biosynthesis of CDP-ascarylose, one of the naturally occurring 3,6-dideoxyhexoses, consists of five enzymatic steps, with CDP-6-deoxy-delta 3,4-glucoseen reductase (E3) participating as the key enzyme in this catalysis. This enzyme has been previously purified from Yersinia pseudotuberculosis by an unusual procedure (protocol I) including a trypsin digestion step (O. Han, V.P. Miller, and H.-W. Liu, J. Biol. Chem. 265:8033-8041, 1990). However, the cloned gene showed disparity with the expected gene characteristics, and upon expression, the resulting gene product exhibited no E3 activity. These findings strongly suggested that the protein isolated by protocol I may have been misidentified as E3. A reinvestigation of the purification protocol produced a new and improved procedure (protocol II) consisting of DEAE-Sephacel, phenyl-Sepharose, Cibacron blue A, and Sephadex G-100 chromatography, which efficiently yielded a new homogeneous enzyme composed of a single polypeptide with a molecular weight of 39,000. This highly purified protein had a specific activity nearly 8,000-fold higher than that of cell lysates, and more importantly, the corresponding gene (ascD) was found to be part of the ascarylose biosynthetic cluster. Presented are the identification and confirmation of the E3 gene through cloning and overexpression and the culminating purification and unambiguous assignment of homogeneous E3. The nucleotide and translated amino acid sequences of the genuine E3 are also presented.

Composition and method for inhibiting plant disease

Abstract: The present invention is directed to methods and compositions for biological control of plant diseases using suppressive avirulent strains of Streptomyces spp. to control disease on a vegetable or other susceptible crop. The method includes applying one or more naturally occurring, suppressive avirulent strains of Streptomyces spp. to the crop to inhibit the growth of Streptomyces scabies or other plant pathogenic organisms that cause scab, wilt, or seedling blight disease. Preferably, at least two suppressive avirulent strains of Streptomyces spp. are applied to reduce the change of resistance from occurring. The suppressive avirulent strains are compatible and will grow in the presence of one another and, when combined with the pathogenic organism, at least one of the suppressive avirulent strains preferably substantially outgrows the pathogen.