Showing papers by "Janet L. Schottel published in 1995"
TL;DR: The crystal structure of a novel esterase from Streptomyces scabies, a causal agent of the potato scab disease, was solved at 2.1 Å resolution and constitutes the first known natural variation of the chymotrypsin-like triad in which a carboxylic acid is replaced by a neutral hydrogen-bond acceptor.
Abstract: The crystal structure of a novel esterase from Streptomyces scabies , a causal agent of the potato scab disease, was solved at 2.1 A resolution. The tertiary fold of the enzyme is substantially different from that of the α/β hydrolase family and unique among all known hydrolases. The active site contains a dyad of Ser 14 and His 283, closely resembling two of the three components of typical Ser-His-Asp(Glu) triads from other serine hydrolases. Proper orientation of the active site imidazol is maintained by a hydrogen bond between the Nδ-H group and a main chain oxygen. Thus, the enzyme constitutes the first known natural variation of the chymotrypsin-like triad in which a carboxylic acid is replaced by a neutral hydrogen-bond acceptor.
143 citations
TL;DR: Complementation, co-plating, antibiotic, and taxonomic tests were used to identify pathogenic and suppressive species of Streptomyces and placed the 17 strains into seven groups that were consistent with the taxonomic work.
Abstract: Complementation, co-plating, antibiotic, and taxonomic tests were used to identify pathogenic and suppressive species of Streptomyces. Of 17 strains of Streptomyces (16 from potato tubers and one from garden beet), 13 were determined to be S. scabies, two were S. diastatochromogenes, one was S. albogriseolus, and one could not be identified. Only the 13 S. scabies strains and the one unidentified russet scab strain were pathogenic on leaf-bud tubers. Prototrophs between auxotrophic mutants formed only in intraspecies pairings, and for S. scabies at rates of 1. 11 and 1.43% for intra- and interstrain pairings, respectively. Tests involving inhibitory reactions of paired strains supported the taxonomic study. In co-plating tests, the type A (lethal zygosislike) reaction occurred only in interspecies pairings. The type B reaction indicated production of and sensitivity to inhibitory compounds. Antibiotic assays confirmed the type B reactions and placed the 17 strains into seven groups that were consistent with the taxonomic work. Three strains, two S. diastatochromogenes and one S. albogriseolus, obtained from a potato scab plot that had become suppressive, produced antibiotic-like compounds against highly pathogenic strains of S. scabies
76 citations
TL;DR: The proposed gene and transcript organization of the L15-SecY-Adk coding regions in the Ss clone resembles that of Micrococcus luteus which, like the streptomycetes, has a G+C-rich genome.
8 citations