Haem utilization in Vibrio cholerae involves multiple TonB-dependent haem receptors

Authors
Citation
Ar. Mey et Sm. Payne, Haem utilization in Vibrio cholerae involves multiple TonB-dependent haem receptors, MOL MICROB, 42(3), 2001, pp. 835-849
Citations number
64
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Microbiology
Journal title
MOLECULAR MICROBIOLOGY
ISSN journal
0950-382X → ACNP
Volume
42
Issue
3
Year of publication
2001
Pages
835 - 849
Database
ISI
SICI code
0950-382X(200111)42:3<835:HUIVCI>2.0.ZU;2-F
Abstract
Vibrio cholerae has multiple iron transport systems, one of which involves haem uptake through the outer membrane receptor HutA. A hutA mutant had onl y a slight defect in growth using haemin as the iron source, and we show he re that V. cholerae encodes two additional TonB-dependent haem receptors, H utR and HasR. HutR has significant homology to HutA as well as to other out er membrane haem receptors. Membrane fractionation confirmed that HutR is p resent in the outer membrane. The hutR gene was cotranscribed with the upst ream gene ptrB, and expression from the ptrB promoter was negatively regula ted by iron. A hutA, hutR mutant was significantly impaired, but not comple tely defective, in the ability to use haemin as the sole iron source. HasR is most similar to the haemophore-utilizing haem receptors from Pseudomonas aeruginosa and Serratia marcescens. A mutant defective in all three haem r eceptors was unable to use haemin as an iron source. HutA and HutR function ed with either V. cholerae TonB1 or TonB2, but haemin transport through eit her receptor was more efficient in strains carrying the tonB1 system genes. In contrast, haemin uptake through HasR was TonB2 dependent. Efficient uti lization of haemoglobin as an iron source required HutA and TonB1. The trip le haem receptor mutant exhibited no defect in its ability to compete with its Vib(-) parental strain in an infant mouse model of infection, indicatin g that additional iron sources are present in vivo. V. cholerae used haem d erived from marine invertebrate haemoglobins, suggesting that haem may be a vailable to V. cholerae growing in the marine environment.