The Actinobacterial mce4 Locus Encodes a Steroid Transporter
| Autor: | Jie Liu, William W. Mohn, Gordon R. Stewart, Lubbert Dijkhuizen, Lindsay D. Eltis, Sachi Okamoto, Robert van der Geize |
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| Přispěvatelé: | Groningen Biomolecular Sciences and Biotechnology, Host-Microbe Interactions |
| Jazyk: | angličtina |
| Rok vydání: | 2008 |
| Předmět: |
MAMMALIAN-CELL ENTRY
RHODOCOCCUS Operon PROTEINS medicine.medical_treatment Quantitative Trait Loci Locus (genetics) OPERONS Biology Biochemistry Article Steroid Mycobacterium tuberculosis Bacterial Proteins medicine Humans MACROPHAGES Molecular Biology Gene Genetics Permease CHOLESTEROL Biological Transport Transporter Cell Biology Metabolism biology.organism_classification GENE ATP Sterols SURVIVAL MYCOBACTERIUM-TUBERCULOSIS Carrier Proteins |
| Zdroj: | The Journal of Biological Chemistry, 283(51), 35368-35374. AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC |
| ISSN: | 1083-351X 0021-9258 |
| Popis: | Bioinformatic analyses have suggested that Mce proteins in diverse actinobacteria are components of complex ATP-binding cassette transporter systems, comprising more than eight distinct proteins. In Mycobacterium tuberculosis, these proteins are implicated in interactions of this deadly pathogen with its human host. Here, we provide direct evidence that the Mce4 system of Rhodococcus jostii RHA1 is a steroid uptake system. Transcriptional analyses indicate that the system is encoded by an 11-gene operon, up-regulated 4.0-fold during growth on cholesterol versus on pyruvate. Growth of RHA1 on cholesterol and uptake of radiolabeled cholesterol both required expression of genes in the mce4 operon encoding two permeases plus eight additional proteins of unknown function. Cholesterol uptake was ATP-dependent and exhibited Michaelis-Menten kinetics with a K(m) of 0.6 +/- 0.1 mu M. This uptake system was also essential for growth of RHA1 on beta-sitosterol, 5-alpha-cholestanol, and 5-alpha-cholestanone. Bioinformatic analysis revealed that all mce4 loci in sequenced genomes are linked to steroid metabolism genes. Thus, we predict that all Mce4 systems are steroid transporters. The transport function of the Mce4 system is consistent with proposed roles of cholesterol and its metabolism in the pathogenesis of M. tuberculosis. |
| Databáze: | OpenAIRE |
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