Initial step in the catabolism of cholesterol by Mycobacterium smegmatis mc2 155.
Environ Microbiol
; 13(4): 943-59, 2011 Apr.
Article
em En
| MEDLINE
| ID: mdl-21208358
ABSTRACT
The first step in the catabolism of cholesterol, i.e. the transformation of cholesterol into cholestenone, has been investigated in Mycobacterium smegmatis. In silico analysis identified the MSMEG_1604 gene encoding a putative protein similar to the ChoD cholesterol oxidase of M. tuberculosis H37Rv (Rv3409c) and the MSMEG_5228 gene coding for a protein similar to the NAD(P)-dependent cholesterol dehydrogenase/isomerase of Nocardia sp. The expression of the MSMEG_5228 gene was inducible by cholesterol whereas the expression of MSMEG_1604 gene was constitutive. When both genes were expressed in Escherichia coli only the MSMEG_5228 protein was active on cholesterol. The function of ChoD-like MSMEG_1604 protein remains to be elucidated, but it does not appear to play a critical role in the mineralization of cholesterol as a MSMEG_1604(-) mutant was not affected in the production of cholestenone. However, a MSMEG_5228(-) mutant showed a drastic reduction in the synthesis of cholestenone. The finding that this mutant was still able to grow in cholesterol, allowed us to demonstrate that the cholesterol-inducible MSMEG_5233 gene encodes an additional cholesterol dehydrogenase/isomerase similar to the AcmA dehydrogenase of Sterolibacterium denitrificans. The observation that the double MSMEG_5228-5233(-) mutant was able to grow in cholesterol suggests that in addition to these enzymes other dehydrogenase/isomerases can also catalyse the first reaction of the cholesterol degradation pathway in M. smegmatis, which is not the limiting step of the process.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Oxirredutases
/
Colesterol
/
Mycobacterium smegmatis
/
Isomerases
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Environ Microbiol
Assunto da revista:
MICROBIOLOGIA
/
SAUDE AMBIENTAL
Ano de publicação:
2011
Tipo de documento:
Article
País de afiliação:
Espanha