Mce3R, a TetR-type transcriptional repressor, controls the expression of a regulon involved in lipid metabolism in Mycobacterium tuberculosis

• Published in: Microbiology (Society for General Microbiology) 2009-07, Vol.155 (7), p.2245-2255
• Main Authors: Santangelo, Maria de la Paz, Klepp, Laura, Nunez-Garcia, Javier, Blanco, Federico C, Soria, Marcelo, Garcia-Pelayo, Maria del Carmen, Bianco, Maria Veronica, Cataldi, Angel A, Golby, Paul, Jackson, Mary, Gordon, Stephen V, Bigi, Fabiana
• Format: Article
• Language: English
• Subjects: Animals; Bacterial Proteins - physiology; Bacteriology; Base Sequence; Biological and medical sciences; Cell Line; Conserved Sequence; DNA, Bacterial - analysis; DNA, Bacterial - genetics; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Bacterial; Lipid Metabolism; Lipids - analysis; Mice; Microbiology; Miscellaneous; Molecular Sequence Data; Mycobacterium tuberculosis; Mycobacterium tuberculosis - genetics; Mycobacterium tuberculosis - metabolism; Oligonucleotide Array Sequence Analysis; Oxidation-Reduction; Promoter Regions, Genetic; Regulon; Repressor Proteins - physiology
• ISSN: 1350-0872; 1465-2080
• DOI: 10.1099/mic.0.027086-0

1 Instituto de Biotecnología, CICVyA-INTA, N. Repetto and De los Reseros, 1686 Hurlingham, Argentina 2 Veterinary Laboratories Agency (Weybridge), New Haw, Addlestone, Surrey KT15 3NB, UK 3 Microbiología Agrícola Facultad de Agronomía, Universidad de Buenos Aires, Av. San Martin 4453, 1417 Buenos Aires, Argentina 4 Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA The mce operons constitute four homologous regions in the Mycobacterium tuberculosis genome, each of which has 8–13 ORFs. Although the function of the Mce protein family has not been clearly established, its members are believed to be membrane lipid transporters. Based on functional experiments, we found that the regulator of the mce3 locus, Mce3R, negatively regulates the expression of the Rv1933c–Rv1935c and Rv1936–Rv1941 transcriptional units. These operons are adjacent to one another and divergently transcribed. The predicted functions of most of these genes are related to either lipid metabolism or redox reactions. Bioinformatic analysis of the 5' UTR sequences of the differentially expressed genes allowed us to define a putative Mce3R motif. Importantly, the Mce3R motif was present six and three times in the mce3R–yrbE3A and Rv1935c–Rv1936 intergenic regions, respectively. Two occurrences of this motif mapped within the two regions of the mce3 operon that were protected by Mce3R in a footprinting analysis, thus indicating that this motif is likely to serve as an operator site for the Mce3R regulator in the promoter. In addition, alterations in the lipid content of M. tuberculosis were detected in the absence of Mce3R. Taken together, these results suggest that Mce3R controls the expression of both the putative transport system encoded in the mce3 operon and the enzymes implicated in the modification of the Mce3-transported substrates. Correspondence Fabiana Bigi fbigi{at}cnia.inta.gov.ar Abbreviations: CDS, coding sequences; RT-qPCR, real-time quantitative polymerase chain reaction; TA, toxin–antitoxin These authors contributed equally to this work. Present address: UCD College of Life Sciences and UCD Conway Institute of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland. The ArrayExpress accession number for the microarray data associated with this paper is E-MEXP-2202. The array design is available in µG@Sbase, accession no. A-BUGS-31 ( http://bugs.