Norepinephrine mediates acquisition of transferrin-iron in Bordetella bronchiseptica.
Previous research demonstrated that the sympathoadrenal catecholamine norepinephrine could promote the growth of Bordetella bronchiseptica in iron-restricted medium containing serum. In this study, norepinephrine was demonstrated to stimulate growth of this organism in the presence of partially iron-saturated transferrin but not lactoferrin. Although norepinephrine is known to induce transcription of the Bordetella bfeA enterobactin catechol xenosiderophore receptor gene, neither a bfeA mutant nor a bfeR regulator mutant was defective in growth responsiveness to norepinephrine. However, growth of a tonB mutant strain was not enhanced by norepinephrine, indicating that the response to this catecholamine was the result of high-affinity outer membrane transport. The B. bronchiseptica genome encodes a total of 19 known and predicted iron transport receptor genes, none of which, when mutated individually, were found to confer a defect in norepinephrine-mediated growth stimulation in the presence of transferrin. Labeling experiments demonstrated a TonB-dependent increase in cell-associated iron levels when bacteria grown in the presence of (55)Fe-transferrin were exposed to norepinephrine. In addition, TonB was required for maximum levels of cell-associated norepinephrine. Together, these results demonstrate that norepinephrine facilitates B. bronchiseptica iron acquisition from the iron carrier protein transferrin and this process may represent a mechanism by which some bacterial pathogens obtain this essential nutrient in the host environment.
Anderson
Mark T
MT
Department of Microbiology, University of Minnesota, Minneapolis, MN 55455-0312, USA.
Armstrong
Sandra K
SK
D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D016950:Bordetella bronchiseptica / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D006877:Hydroxamic Acids / Q000378:metabolism; D007501:Iron / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D009638:Norepinephrine / Q000494:pharmacology*; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D013566:Sympathomimetics / Q000494:pharmacology; D014168:Transferrin / Q000378:metabolism*
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D006877:Hydroxamic Acids; D008565:Membrane Proteins; D011956:Receptors, Cell Surface; D013566:Sympathomimetics; D014168:Transferrin; C092056:alcaligin; C029489:enterobactin receptor; C057616:tonB protein, Bacteria; D007501:Iron; D009638:Norepinephrine