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Improved broad-host-range plasmid vectors were constructed based on existing plasmids RSF1010 and RK404. The new plasmids pDSK509, pDSK519, and pRK415, have several additional cloning sites and improved antibiotic-resistance genes which facilitate subcloning and mobilization into various Gram-negative bacteria. Several new polylinker sites were added to the(More)
A wide-host-range cosmid cloning vector, pLAFR3, was constructed and used to make cosmid libraries of partially digested Sau3A DNA from race 0 and race 1 of Pseudomonas syringae pv. glycinea. Two avirulence genes, avrB0 and avrC, cloned from race 0, elicited the hypersensitivity reaction (HR) on specific cultivars of soybean. Race 4 transconjugants(More)
Phyllosphere microbial communities were evaluated on leaves of field-grown plant species by culture-dependent and -independent methods. Denaturing gradient gel electrophoresis (DGGE) with 16S rDNA primers generally indicated that microbial community structures were similar on different individuals of the same plant species, but unique on different plant(More)
Pectate lyases are secreted by pathogens and initiate soft-rot diseases in plants by cleaving polygalacturonate, a major component of the plant cell wall. The three-dimensional structure of pectate lyase C from Erwinia chrysanthemi has been solved and refined to a resolution of 2.2 angstroms. The enzyme folds into a unique motif of parallel beta strands(More)
The cloning of avirulence genes has greatly aided our understanding of plant-pathogen specificity. It has proven that the gene-for-gene relationship first noted by Flor is correct--single avirulence gene encoding single protein products indeed are the genetic elements that interact with plant disease resistance genes. Furthermore, firm genetic evidence has(More)
The pelA and pelC genes from Erwinia chrysanthemi EC16 were sequenced and overexpressed in Escherichia coli cells. These genes and two others from the same strain that were characterized previously encode catalytically related pectate lyase proteins that are involved with the maceration and soft-rotting of plant tissue. The pel genes of strain EC16 were(More)
We developed improved virulence assays for Erwinia chrysanthemi 3937 on African violet varieties and devised a new method for the construction of precise bacterial gene knockouts. These methods were tested by constructing mutations in genes suspected to be involved with plant interactions. The virulence of the hrpG and hrcC mutant strains (both gene(More)
A community-based survey was used to assess the prevalence of risk factors for coronary heart disease (CHD) in rural Tanzanians. In all, 8581 subjects (3705 men, 4876 women) aged > or = 15 years in eight villages in three regions in rural Tanzania representing a range of socioeconomic deprivation were studied. The main outcome measures were serum(More)
The three-dimensional structure of a complex between the pectate lyase C (PelC) R218K mutant and a plant cell wall fragment has been determined by x-ray diffraction techniques to a resolution of 2.2 A and refined to a crystallographic R factor of 18.6%. The oligosaccharide substrate, alpha-D-GalpA-([1-->4]-alpha-D-GalpA)3-(1-->4)-D-GalpA , is composed of(More)
The pelB and pelE genes from Erwinia chrysanthemi EC16, which encode different pectate lyase enzymes, were sequenced and expressed at a high level in Escherichia coli. The genes possessed little similarity to each other in 5' signal regions, signal peptide sequences, coding sequences, or 3' noncoding regions. Both genes contained their own promoters as well(More)