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A novel antioxidant gene from Mycobacterium tuberculosis.

Ehrt S, Shiloh MU, Ruan J, Choi M, Gunzburg S, Nathan C, Xie Q, Riley LW - J. Exp. Med. (1997)

Bottom Line: Among the major antimicrobial products of macrophages are reactive intermediates of the oxidation of nitrogen (RNI) and the reduction of oxygen (ROI).Expression of noxR1 conferred upon Escherichia coli and Mycobacterium smegmatis enhanced ability to resist RNI and ROI, whether the bacteria were exposed to exogenous compounds in medium or to endogenous products in macrophages.These studies provide the first identification of an RNI resistance mechanism in mycobacteria, point to a new mechanism for resistance to ROI, and raise the possibility that inhibition of the noxR1 pathway might enhance the ability of macrophages to control tuberculosis.

View Article: PubMed Central - PubMed

Affiliation: Division of International Medicine and Infectious Disease, Department of Medicine, Cornell University Medical College, New York 10021, USA.

ABSTRACT
Among the major antimicrobial products of macrophages are reactive intermediates of the oxidation of nitrogen (RNI) and the reduction of oxygen (ROI). Selection of recombinants in acidified nitrite led to the cloning of a novel gene, noxR1, from a pathogenic clinical isolate of Mycobacterium tuberculosis. Expression of noxR1 conferred upon Escherichia coli and Mycobacterium smegmatis enhanced ability to resist RNI and ROI, whether the bacteria were exposed to exogenous compounds in medium or to endogenous products in macrophages. These studies provide the first identification of an RNI resistance mechanism in mycobacteria, point to a new mechanism for resistance to ROI, and raise the possibility that inhibition of the noxR1 pathway might enhance the ability of macrophages to control tuberculosis.

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Molecular analysis  of the cloned DNA. (A) Presence of noxR1 in different species of mycobacteria. Chromosomal DNA (1 μg) of each strain  was digested to completion with  EcoRI and analyzed by Southern  blotting with a digoxigenin-labeled  probe corresponding to the  0.68-kb fragment from pNO14.  Lane 1, Mr markers; lane 2, M.  tuberculosis CB3.3; lane 3, M. tuberculosis H37Ra; lane 4, M. tuberculosis H37Rv; lane 5, M. bovis; lane  6, M. africanum; lane 7, M. gordonae; lane 8, M. fortuitum; lane 9,  M. smegmatis; lane 10, M. avium;  lane 11, M. intracellulare; lane 12,  M. kansassi. (B) Map of the inserts in pNO14 and pNO16. (C)  Nucleotide sequence of the NO14  fragment and amino acid sequence  of the putative protein encoded  by ORF1 (noxR1). These sequence data are available from  the EMBL/GenBank/DDBJ under accession number Y08323.  (D) Hydrophilicity plot of putative protein (NoxR1) encoded  by ORF1.
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Figure 2: Molecular analysis of the cloned DNA. (A) Presence of noxR1 in different species of mycobacteria. Chromosomal DNA (1 μg) of each strain was digested to completion with EcoRI and analyzed by Southern blotting with a digoxigenin-labeled probe corresponding to the 0.68-kb fragment from pNO14. Lane 1, Mr markers; lane 2, M. tuberculosis CB3.3; lane 3, M. tuberculosis H37Ra; lane 4, M. tuberculosis H37Rv; lane 5, M. bovis; lane 6, M. africanum; lane 7, M. gordonae; lane 8, M. fortuitum; lane 9, M. smegmatis; lane 10, M. avium; lane 11, M. intracellulare; lane 12, M. kansassi. (B) Map of the inserts in pNO14 and pNO16. (C) Nucleotide sequence of the NO14 fragment and amino acid sequence of the putative protein encoded by ORF1 (noxR1). These sequence data are available from the EMBL/GenBank/DDBJ under accession number Y08323. (D) Hydrophilicity plot of putative protein (NoxR1) encoded by ORF1.

Mentions: The cloned 680-bp fragment hybridized to genomes of the members of the M. tuberculosis complex. None of the other mycobacterial strains tested hybridized with this probe (Fig. 2 A). Thus, among mycobacteria, the cloned DNA appears to be specific for the members of the M. tuberculosis complex associated with human and rodent disease.


A novel antioxidant gene from Mycobacterium tuberculosis.

Ehrt S, Shiloh MU, Ruan J, Choi M, Gunzburg S, Nathan C, Xie Q, Riley LW - J. Exp. Med. (1997)

Molecular analysis  of the cloned DNA. (A) Presence of noxR1 in different species of mycobacteria. Chromosomal DNA (1 μg) of each strain  was digested to completion with  EcoRI and analyzed by Southern  blotting with a digoxigenin-labeled  probe corresponding to the  0.68-kb fragment from pNO14.  Lane 1, Mr markers; lane 2, M.  tuberculosis CB3.3; lane 3, M. tuberculosis H37Ra; lane 4, M. tuberculosis H37Rv; lane 5, M. bovis; lane  6, M. africanum; lane 7, M. gordonae; lane 8, M. fortuitum; lane 9,  M. smegmatis; lane 10, M. avium;  lane 11, M. intracellulare; lane 12,  M. kansassi. (B) Map of the inserts in pNO14 and pNO16. (C)  Nucleotide sequence of the NO14  fragment and amino acid sequence  of the putative protein encoded  by ORF1 (noxR1). These sequence data are available from  the EMBL/GenBank/DDBJ under accession number Y08323.  (D) Hydrophilicity plot of putative protein (NoxR1) encoded  by ORF1.
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Related In: Results  -  Collection

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Figure 2: Molecular analysis of the cloned DNA. (A) Presence of noxR1 in different species of mycobacteria. Chromosomal DNA (1 μg) of each strain was digested to completion with EcoRI and analyzed by Southern blotting with a digoxigenin-labeled probe corresponding to the 0.68-kb fragment from pNO14. Lane 1, Mr markers; lane 2, M. tuberculosis CB3.3; lane 3, M. tuberculosis H37Ra; lane 4, M. tuberculosis H37Rv; lane 5, M. bovis; lane 6, M. africanum; lane 7, M. gordonae; lane 8, M. fortuitum; lane 9, M. smegmatis; lane 10, M. avium; lane 11, M. intracellulare; lane 12, M. kansassi. (B) Map of the inserts in pNO14 and pNO16. (C) Nucleotide sequence of the NO14 fragment and amino acid sequence of the putative protein encoded by ORF1 (noxR1). These sequence data are available from the EMBL/GenBank/DDBJ under accession number Y08323. (D) Hydrophilicity plot of putative protein (NoxR1) encoded by ORF1.
Mentions: The cloned 680-bp fragment hybridized to genomes of the members of the M. tuberculosis complex. None of the other mycobacterial strains tested hybridized with this probe (Fig. 2 A). Thus, among mycobacteria, the cloned DNA appears to be specific for the members of the M. tuberculosis complex associated with human and rodent disease.

Bottom Line: Among the major antimicrobial products of macrophages are reactive intermediates of the oxidation of nitrogen (RNI) and the reduction of oxygen (ROI).Expression of noxR1 conferred upon Escherichia coli and Mycobacterium smegmatis enhanced ability to resist RNI and ROI, whether the bacteria were exposed to exogenous compounds in medium or to endogenous products in macrophages.These studies provide the first identification of an RNI resistance mechanism in mycobacteria, point to a new mechanism for resistance to ROI, and raise the possibility that inhibition of the noxR1 pathway might enhance the ability of macrophages to control tuberculosis.

View Article: PubMed Central - PubMed

Affiliation: Division of International Medicine and Infectious Disease, Department of Medicine, Cornell University Medical College, New York 10021, USA.

ABSTRACT
Among the major antimicrobial products of macrophages are reactive intermediates of the oxidation of nitrogen (RNI) and the reduction of oxygen (ROI). Selection of recombinants in acidified nitrite led to the cloning of a novel gene, noxR1, from a pathogenic clinical isolate of Mycobacterium tuberculosis. Expression of noxR1 conferred upon Escherichia coli and Mycobacterium smegmatis enhanced ability to resist RNI and ROI, whether the bacteria were exposed to exogenous compounds in medium or to endogenous products in macrophages. These studies provide the first identification of an RNI resistance mechanism in mycobacteria, point to a new mechanism for resistance to ROI, and raise the possibility that inhibition of the noxR1 pathway might enhance the ability of macrophages to control tuberculosis.

Show MeSH
Related in: MedlinePlus