The Mycobacterium tuberculosis Rv2358-furB operon is induced by zinc.
The Mycobacterium tuberculosis genome encodes two ferric uptake regulator homologues, furA and furB, the function of which is under investigation. Using Mycobacterium smegmatis as a model system, we investigated the transcriptional pattern of Rv(Ms)2358-furB genes. Transcripts covering the two genes could be identified by northern blotting and by reverse transcriptase PCR. The transcriptional start point was mapped at one base upstream of the Ms2358 start codon by the RACE technique. By cloning M. smegmatis and M. tuberculosis DNA regions upstream of a reporter gene, we demonstrated the presence of one promoter, located immediately upstream of the Rv(Ms)2358 gene. Promoter induction was tested on several cultures grown under different conditions of pH and temperature, and in the presence of different concentrations of metallic ions. The promoter was found to be specifically induced by zinc. The recombinant M. tuberculosis FurB protein typically contained two zinc ions per protein monomer. Complete removal of zinc could not be obtained, even with strong denaturation treatment. Our data are in favour of the hypothesis that Rv2358 and FurB are transcriptional regulators involved in zinc homeostasis.
Milano
Anna
A
Dipartimento di Genetica e Microbiologia, Università degli Studi di Pavia, via Ferrata 1, 27100 Pavia, Italy.
Branzoni
Manuela
M
Canneva
Fabio
F
Profumo
Antonella
A
Riccardi
Giovanna
G
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D020102:Mycobacterium smegmatis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D009876:Operon / Q000187:drug effects* / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics / Q000502:physiology; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics; D019105:Random Amplified Polymorphic DNA Technique; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D015032:Zinc / Q000378:metabolism / Q000494:pharmacology*
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012329:RNA, Bacterial; D012097:Repressor Proteins; C068477:ferric uptake regulating proteins, bacterial; D015032:Zinc