Azole antifungals are potent inhibitors of cytochrome P450 mono-oxygenases and bacterial growth in mycobacteria and streptomycetes

Kirsty J. McLean, Ker R. Marshall, Alison Richmond, Iain S. Hunter, Kay Fowler, Tobias Kieser, Sudagar S. Gurcha, Gurydal S. Besra, Andrew W. Munro

Research output: Contribution to journalArticle

148 Citations (Scopus)

Abstract

The genome sequence of Mycobacterium tuberculosis has revealed the presence of 20 different cytochrome P450 mono-oxygenases (P450s) within this organism, and subsequent genome sequences of other mycobacteria and of Streptomyces coelicolor have indicated that these actinomycetes also have large complements of P450s, pointing to important physiological roles for these enzymes. The actinomycete P450s include homologues of 14{alpha}-sterol demethylases, the targets for the azole class of drugs in yeast and fungi. Previously, this type of P450 was considered to be absent from bacteria. When present at low concentrations in growth medium, azole antifungal drugs were shown to be potent inhibitors of the growth of Mycobacterium smegmatis and of Streptomyces strains, indicating that one or more of the P450s in these bacteria were viable drug targets. The drugs econazole and clotrimazole were most effective against M. smegmatis (MIC values of <0·2 and 0·3 µM, respectively) and were superior inhibitors of mycobacterial growth compared to rifampicin and isoniazid (which had MIC values of 1·2 and 36·5 µM, respectively). In contrast to their effects on the actinomycetes, the azoles showed minimal effects on the growth of Escherichia coli, which is devoid of P450s. Azole drugs coordinated tightly to the haem iron in M. tuberculosis H37Rv P450s encoded by genes Rv0764c (the sterol demethylase CYP51) and Rv2276 (CYP121). However, the azoles had a higher affinity for M. tuberculosis CYP121, with Kd values broadly in line with the MIC values for M. smegmatis. This suggested that CYP121 may be a more realistic target enzyme for the azole drugs than CYP51, particularly in light of the fact that an S. coelicolor {Delta}CYP51 strain was viable and showed little difference in its sensitivity to azole drugs compared to the wild-type. If the azole drugs prove to inhibit a number of important P450s in M. smegmatis and S. coelicolor, then the likelihood of drug resistance developing in these species should be minimal. This suggests that azole drug therapy may provide a novel antibiotic strategy against strains of M. tuberculosis that have already developed resistance to isoniazid and other front-line drugs.
Original languageEnglish
Pages (from-to)2937-2949
Number of pages12
JournalMicrobiology
Volume148
Publication statusPublished - 1 Oct 2002

Fingerprint

Azoles
Oxygenases
Mycobacterium
Cytochrome P-450 Enzyme System
Mycobacterium smegmatis
Growth
Pharmaceutical Preparations
Streptomyces coelicolor
Mycobacterium tuberculosis
Actinobacteria
Growth Inhibitors
Isoniazid
Sterol 14-Demethylase
Econazole
Genome
Clotrimazole
Bacteria
Streptomyces
Sterols
Enzymes

Keywords

  • tuberculosis
  • azole drugs
  • immunology
  • disease
  • pharmacology
  • microbiology

Cite this

McLean, K. J., Marshall, K. R., Richmond, A., Hunter, I. S., Fowler, K., Kieser, T., ... Munro, A. W. (2002). Azole antifungals are potent inhibitors of cytochrome P450 mono-oxygenases and bacterial growth in mycobacteria and streptomycetes. Microbiology, 148, 2937-2949.
McLean, Kirsty J. ; Marshall, Ker R. ; Richmond, Alison ; Hunter, Iain S. ; Fowler, Kay ; Kieser, Tobias ; Gurcha, Sudagar S. ; Besra, Gurydal S. ; Munro, Andrew W. / Azole antifungals are potent inhibitors of cytochrome P450 mono-oxygenases and bacterial growth in mycobacteria and streptomycetes. In: Microbiology. 2002 ; Vol. 148. pp. 2937-2949.
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McLean, KJ, Marshall, KR, Richmond, A, Hunter, IS, Fowler, K, Kieser, T, Gurcha, SS, Besra, GS & Munro, AW 2002, 'Azole antifungals are potent inhibitors of cytochrome P450 mono-oxygenases and bacterial growth in mycobacteria and streptomycetes', Microbiology, vol. 148, pp. 2937-2949.

Azole antifungals are potent inhibitors of cytochrome P450 mono-oxygenases and bacterial growth in mycobacteria and streptomycetes. / McLean, Kirsty J.; Marshall, Ker R.; Richmond, Alison; Hunter, Iain S.; Fowler, Kay; Kieser, Tobias; Gurcha, Sudagar S.; Besra, Gurydal S.; Munro, Andrew W.

In: Microbiology, Vol. 148, 01.10.2002, p. 2937-2949.

Research output: Contribution to journalArticle

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T1 - Azole antifungals are potent inhibitors of cytochrome P450 mono-oxygenases and bacterial growth in mycobacteria and streptomycetes

AU - McLean, Kirsty J.

AU - Marshall, Ker R.

AU - Richmond, Alison

AU - Hunter, Iain S.

AU - Fowler, Kay

AU - Kieser, Tobias

AU - Gurcha, Sudagar S.

AU - Besra, Gurydal S.

AU - Munro, Andrew W.

PY - 2002/10/1

Y1 - 2002/10/1

N2 - The genome sequence of Mycobacterium tuberculosis has revealed the presence of 20 different cytochrome P450 mono-oxygenases (P450s) within this organism, and subsequent genome sequences of other mycobacteria and of Streptomyces coelicolor have indicated that these actinomycetes also have large complements of P450s, pointing to important physiological roles for these enzymes. The actinomycete P450s include homologues of 14{alpha}-sterol demethylases, the targets for the azole class of drugs in yeast and fungi. Previously, this type of P450 was considered to be absent from bacteria. When present at low concentrations in growth medium, azole antifungal drugs were shown to be potent inhibitors of the growth of Mycobacterium smegmatis and of Streptomyces strains, indicating that one or more of the P450s in these bacteria were viable drug targets. The drugs econazole and clotrimazole were most effective against M. smegmatis (MIC values of <0·2 and 0·3 µM, respectively) and were superior inhibitors of mycobacterial growth compared to rifampicin and isoniazid (which had MIC values of 1·2 and 36·5 µM, respectively). In contrast to their effects on the actinomycetes, the azoles showed minimal effects on the growth of Escherichia coli, which is devoid of P450s. Azole drugs coordinated tightly to the haem iron in M. tuberculosis H37Rv P450s encoded by genes Rv0764c (the sterol demethylase CYP51) and Rv2276 (CYP121). However, the azoles had a higher affinity for M. tuberculosis CYP121, with Kd values broadly in line with the MIC values for M. smegmatis. This suggested that CYP121 may be a more realistic target enzyme for the azole drugs than CYP51, particularly in light of the fact that an S. coelicolor {Delta}CYP51 strain was viable and showed little difference in its sensitivity to azole drugs compared to the wild-type. If the azole drugs prove to inhibit a number of important P450s in M. smegmatis and S. coelicolor, then the likelihood of drug resistance developing in these species should be minimal. This suggests that azole drug therapy may provide a novel antibiotic strategy against strains of M. tuberculosis that have already developed resistance to isoniazid and other front-line drugs.

AB - The genome sequence of Mycobacterium tuberculosis has revealed the presence of 20 different cytochrome P450 mono-oxygenases (P450s) within this organism, and subsequent genome sequences of other mycobacteria and of Streptomyces coelicolor have indicated that these actinomycetes also have large complements of P450s, pointing to important physiological roles for these enzymes. The actinomycete P450s include homologues of 14{alpha}-sterol demethylases, the targets for the azole class of drugs in yeast and fungi. Previously, this type of P450 was considered to be absent from bacteria. When present at low concentrations in growth medium, azole antifungal drugs were shown to be potent inhibitors of the growth of Mycobacterium smegmatis and of Streptomyces strains, indicating that one or more of the P450s in these bacteria were viable drug targets. The drugs econazole and clotrimazole were most effective against M. smegmatis (MIC values of <0·2 and 0·3 µM, respectively) and were superior inhibitors of mycobacterial growth compared to rifampicin and isoniazid (which had MIC values of 1·2 and 36·5 µM, respectively). In contrast to their effects on the actinomycetes, the azoles showed minimal effects on the growth of Escherichia coli, which is devoid of P450s. Azole drugs coordinated tightly to the haem iron in M. tuberculosis H37Rv P450s encoded by genes Rv0764c (the sterol demethylase CYP51) and Rv2276 (CYP121). However, the azoles had a higher affinity for M. tuberculosis CYP121, with Kd values broadly in line with the MIC values for M. smegmatis. This suggested that CYP121 may be a more realistic target enzyme for the azole drugs than CYP51, particularly in light of the fact that an S. coelicolor {Delta}CYP51 strain was viable and showed little difference in its sensitivity to azole drugs compared to the wild-type. If the azole drugs prove to inhibit a number of important P450s in M. smegmatis and S. coelicolor, then the likelihood of drug resistance developing in these species should be minimal. This suggests that azole drug therapy may provide a novel antibiotic strategy against strains of M. tuberculosis that have already developed resistance to isoniazid and other front-line drugs.

KW - tuberculosis

KW - azole drugs

KW - immunology

KW - disease

KW - pharmacology

KW - microbiology

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JO - Microbiology

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SN - 1350-0872

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McLean KJ, Marshall KR, Richmond A, Hunter IS, Fowler K, Kieser T et al. Azole antifungals are potent inhibitors of cytochrome P450 mono-oxygenases and bacterial growth in mycobacteria and streptomycetes. Microbiology. 2002 Oct 1;148:2937-2949.