The iron-responsive regulator fur is transcriptionally autoregulated and not essential in Neisseria meningitidis.
Fur is a well-known iron-responsive repressor of gene transcription, which is used by many bacteria to respond to the low-iron environment that pathogens encounter during infection. The fur gene in Neisseria meningitidis has been described as an essential gene that may regulate a broad array of genes. We succeeded in obtaining an N. meningitidis mutant with the fur gene knocked out and used it to undertake studies of fur-mediated iron regulation. We show that expression of both Fur and the transferrin binding protein Tbp2 is iron regulated and demonstrate that this regulation is Fur mediated for the Tbp2 protein. Footprinting analysis revealed that Fur binds to two distinct sites upstream of its coding region with different affinities and that these binding sites overlap two promoters that differentially control transcription of the fur gene in response to iron. The presence of two independently regulated fur promoters may allow meningococcus to fine-tune expression of this regulator controlling iron homeostasis, possibly during infection.
Delany
Isabel
I
Biochemistry and Molecular Biology Unit, IRIS, Chiron S.r.l., 53100 Siena, Italy.
Ieva
Raffaele
R
Alaimo
Cristina
C
Rappuoli
Rino
R
Scarlato
Vincenzo
V
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D003470:Culture Media; D015964:Gene Expression Regulation, Bacterial; D006706:Homeostasis; D007501:Iron / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D009345:Neisseria meningitidis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D033882:Transferrin-Binding Protein B / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D003470:Culture Media; D012097:Repressor Proteins; D033882:Transferrin-Binding Protein B; C068477:ferric uptake regulating proteins, bacterial; D007501:Iron