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Regulation of hmp gene transcription in Mycobacterium tuberculosis: effects of oxygen limitation and nitrosative and oxidative stress.
- Source :
-
Journal of bacteriology [J Bacteriol] 1999 Jun; Vol. 181 (11), pp. 3486-93. - Publication Year :
- 1999
-
Abstract
- The Mycobacterium tuberculosis hmp gene encodes a protein which is homologous to flavohemoglobin in Escherichia coli. Northern blotting analysis demonstrated that hmp transcription increased when a microaerophilic culture became oxygen limited as it entered stationary phase at 20 days. There was a fivefold increase of the hmp transcripts during early stationary phase compared with the value which was observed in the exponential growth phase. This induction of hmp transcription was not due to changes in the mRNA stability since the half-life of hmp mRNA was very short in a 20-day microaerophilic culture. No induction of hmp mRNA was observed during entry into stationary phase when the culture was continuously aerated. hmp transcription was induced after a short exposure of a late-exponential-phase culture to anaerobic conditions. These data indicate that oxygen limitation is the trigger for hmp gene transcription. In addition, when a microaerophilic culture entered into the stationary phase at 20 days, transcription of hmp increased to a small extent after exposure to S-nitrosoglutathione (a nitric oxide [NO] releaser) and sodium nitroprusside (an NO+ donor) and decreased after exposure to paraquat (a superoxide generator) and H2O2. In log phase (4 days) and late stationary phase (40 days), the transcription of hmp was unaffected by nitrosative and oxidative stress. Three primer extension products were observed. The -10 region is 100% identical to that of promoter T3 in mycobacteria and shows a strong similarity to the -10 sequence of hmp and rpoS promoters in E. coli. These observations of hmp mRNA induction in response to O2 limitation and nitrosative stress suggest that the hmp gene of M. tuberculosis may have a role in protection of the organism from NO killing under microaerophilic conditions.
- Subjects :
- Aerobiosis
Anaerobiosis
Base Sequence
Genes, Bacterial genetics
Glutathione analogs & derivatives
Glutathione pharmacology
Hydrogen Peroxide pharmacology
Molecular Sequence Data
Mycobacterium tuberculosis drug effects
Mycobacterium tuberculosis growth & development
Mycobacterium tuberculosis metabolism
Nitroprusside pharmacology
Nitroso Compounds pharmacology
Open Reading Frames genetics
Paraquat pharmacology
Promoter Regions, Genetic genetics
RNA, Bacterial analysis
RNA, Bacterial genetics
RNA, Bacterial metabolism
S-Nitrosoglutathione
Sequence Homology, Amino Acid
Transcription, Genetic drug effects
Transcription, Genetic genetics
Bacterial Proteins genetics
Gene Expression Regulation, Bacterial drug effects
Hemeproteins genetics
Mycobacterium tuberculosis genetics
Nitroso Compounds metabolism
Oxidative Stress drug effects
Oxygen metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0021-9193
- Volume :
- 181
- Issue :
- 11
- Database :
- MEDLINE
- Journal :
- Journal of bacteriology
- Publication Type :
- Academic Journal
- Accession number :
- 10348862
- Full Text :
- https://doi.org/10.1128/JB.181.11.3486-3493.1999