Reaction of Mycobacterium tuberculosis cytochrome P450 enzymes with nitric oxide.
Biochemistry
; 48(5): 863-72, 2009 Feb 10.
Article
em En
| MEDLINE
| ID: mdl-19146393
ABSTRACT
During the initial growth infection stage of Mycobacterium tuberculosis (Mtb), (*)NO produced by host macrophages inhibits heme-containing terminal cytochrome oxidases, inactivates iron/sulfur proteins, and promotes entry into latency. Here we evaluate the potential of (*)NO as an inhibitor of Mtb cytochrome P450 enzymes, as represented by CYP130, CYP51, and the two previously uncharacterized enzymes CYP125 and CYP142. Using UV-visible absorption, resonance Raman, and stopped-flow spectroscopy, we investigated the reactions of (*)NO with these heme proteins in their ferric resting form. (*)NO coordinates tightly to CYP125 and CYP142 (submicromolar) and with a lower affinity (micromolar) to CYP130 and CYP51. Anaerobic reduction of the ferric-NO species with sodium dithionite led to the formation of two spectrally distinct classes of five-coordinate ferrous-NO complexes. Exposure of these species to O(2) revealed that the ferrous-NO forms of CYP125 and CYP142 are labile and convert back to the ferric state within a few minutes, whereas ferrous CYP130 and CYP51 bind (*)NO almost irreversibly. This work clearly indicates that, at physiological concentrations (approximately 1 microM), (*)NO would impair the activity of CYP130 and CYP51, whereas CYP125 and CYP142 are more resistant. Selective P450 inhibition may contribute to the inhibitory effects of (*)NO on Mtb growth.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Bactérias
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Sistema Enzimático do Citocromo P-450
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Mycobacterium tuberculosis
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Óxido Nítrico
Limite:
Animals
Idioma:
En
Ano de publicação:
2009
Tipo de documento:
Article