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Biomedical subjects

J B Neilands

Publications and source records attributed to J B Neilands.

At least 91 records · Page 5Linked to original sources
PubMed1975

Evidence for common binding sites for ferrichrome compounds and bacteriophage phi 80 in the cell envelope of Escherichia coli.

Mutants ton A and ton B of Escherichia coli K12, known to be resistant to bacteriophage phi80, were found to be insensitive as well to albomycin, an analogue of the specific siderochrome ferrichrome. Ferrichrome at micromolar concentrations strongly inhibited plaque production by phi80. Preincubation with ferrichrome did not inactivate the phage. At a concentration at which ferrichrome allowed 90% inhibition of plaque formation, the chromium analogue of ferrichrome showed no detectable activity. Similarly, ethylenediaminetetraacetic acid, ferrichrome A, and certain siderochromes structurally distinct from ferrichrome, such as ferrioxamine B, schizokinen, citrate, and enterobactin, did not show detectable inhibitory activity. However, rhodotorulic acid showed moderate activity. A host range mutant of phi80, phi80h, was also inhibited by ferrichrome, as was a hybrid of phage lambda possessing the host range of phi80. However, phage lambdacI- and a hybrid of phi80 possessing the host range of lambda were not affected by ferrichrome. Finally, ferrichrome and chromic deferriferrichrome were shown to inhibit adsorption of phi80 to sensitive cells, ferrichrome giving 50% inhibition of adsorption at a minimal concentration of 8 nM. It is suggested that a component of the ferrichrome uptake system may reside in the outer membrane of E. coli K12 and may also function as a component of the receptor site for bacteriophage phi80, and that ferrichrome inhibition of the phage represents a competition for this common site.

Adsorption↗
PubMed1972

Iron uptake in Salmonella typhimurium: utilization of exogenous siderochromes as iron carriers.

Aerobic microorganisms have evolved a variety of siderochromes, special ligands which can dissolve insoluble ferric iron and facilitate its transport into the cell. We have found that enb mutants of Salmonella typhimurium blocked in the biosynthesis of enterobactin (its natural iron carrier) are able to utilize siderochromes of different types made by other microorganisms as iron carriers. The antibiotic albomycin delta(2) was used to select mutants defective in ferrichrome-mediated iron uptake. Twelve classes of albomycin-resistant mutants, named sid, were defined on the basis of their growth responses to other siderochromes. Most of these classes have genetic lesions in loci that are cotransduced with panC (represented at 9 min on the genetic map). The locus designated sidJ is cotransduced with enb, whereas sidK and sidL are linked with neither panC nor enb. Genetic and physiological data indicate that S. typhimurium has several transport systems of high specificity for a variety of siderochromes produced by other microorganisms.

Catechols↗
PubMed1971

Salmonellosis pacifarin activity of enterobactin.

Salmonellosis pacifarin activity is detected by an increased survivorship of mice, doubly infected with avirulent and virulent Salmonella typhimurium, when heretofore unknown agents, found in certain natural foodstuffs and in the supernatants of certain bacterial cultures, are fed to the infected animals as dietary supplements. We now announce the identity of one of these agents: it is enterobactin, a cyclic trimer of 2,3-dihydroxy-N-benzoyl-L-serine. Basal diets enriched with as little as 2 mg of crystalline trimer per kg of diet show pacifarin activity to a statistically significant degree. Diets supplemented with as much as 100 mg of the monomer per kg of diet show no such activity.

Animals↗