New aerobactin-mediated iron uptake system in a septicemia-causing strain of Enterobacter cloacae.
Unlike the great majority of the aerobactin-producing enteric bacteria documented in the literature, Enterobacter cloacae EK33, isolated from a case of human neonatal meningitis, did not show any homology at the DNA level with the prototype aerobactin system encoded by the ColV-K30 plasmid. However, both the nuclear magnetic resonance spectrum and fast-atom bombardment mass spectrometry of the siderophore purified from EK33 confirmed its identity with aerobactin. Bioassay screening of a gene library of total DNA of EK33 led to the isolation of several aerobactin-positive clones. Under conditions of iron limitation, these clones expressed in Escherichia coli a protein of 72 kilodaltons that reacted with antiserum raised against the pColV-K30 74-kilodalton aerobactin receptor, while the original E. cloacae strain synthesized an 85-kilodalton protein which also cross-reacted with the antiserum. Restriction endonuclease analysis of the cloned DNA confirmed the structural differences between the two aerobactin genetic systems.
Crosa
L M
LM
Department of Microbiology and Immunology, Oregon Health Sciences University, Portland 97201.
Wolf
M K
MK
Actis
L A
LA
Sanders-Loehr
J
J
Crosa
J H
JH
D003227:Conjugation, Genetic; D004754:Enterobacter / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D004755:Enterobacteriaceae / Q000378:metabolism*; D005798:Genes, Bacterial; D005838:Genotype; D006801:Humans; D006877:Hydroxamic Acids / Q000302:isolation & purification / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D010641:Phenotype; D010957:Plasmids; D018805:Sepsis / Q000382:microbiology
D006877:Hydroxamic Acids; C031819:aerobactin; D007501:Iron