title: Cholesterol utilization in mycobacteria is controlled by two TetR-type transcriptional regulators: kstR and kstR2.
abstract: Mycobacterium tuberculosis is able to use a variety of carbon sources in vivo and current knowledge suggests that cholesterol is used as a carbon source during infection. The catabolized cholesterol is used both as an energy source (ATP generation) and as a source of precursor molecules for the synthesis of complex methyl-branched fatty acids. In previous studies, we described a TetR-type transcriptional repressor, kstR, that controls the expression of a number of genes involved in cholesterol catabolism. In this study, we describe a second TetR-type repressor, which we call kstR2. We knocked this gene out in Mycobacterium smegmatis and used microarrays and quantitative RT-PCR to examine the effects on gene expression. We identified a palindromic regulatory motif for KstR2, showed that this motif is present in three promoter regions in mycobacteria and rhodococcus, and demonstrated binding of purified KstR2 to the motif. Using a combination of motif location analysis, gene expression analysis and the examination of gene conservation, we suggest that kstR2 controls the expression of a 15 gene regulon. Like kstR, kstR2 and the kstR2 regulon are highly conserved among the actinomycetes and studies in rhodococcus suggest a role for these genes in cholesterol catabolism. The functional significance of the regulon and implications for the control of cholesterol utilization are discussed.
authors.affiliation: Department of Pathology and Infectious Diseases, The Royal Veterinary College, Centre for Emerging, Endemic and Exotic Disease, Hawkshead Lane, Hertfordshire, AL9 7TA, UK.
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Kendall
authors.affiliation: Department of Pathology and Infectious Diseases, The Royal Veterinary College, Centre for Emerging, Endemic and Exotic Disease, Hawkshead Lane, Hertfordshire, AL9 7TA, UK.
authors.forename: Philippa
authors.initials: P
authors.lastname: Burgess
authors.affiliation: Department of Pathology and Infectious Diseases, The Royal Veterinary College, Centre for Emerging, Endemic and Exotic Disease, Hawkshead Lane, Hertfordshire, AL9 7TA, UK.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Balhana
authors.affiliation: Department of Pathology and Infectious Diseases, The Royal Veterinary College, Centre for Emerging, Endemic and Exotic Disease, Hawkshead Lane, Hertfordshire, AL9 7TA, UK.
authors.forename: Mike
authors.initials: M
authors.lastname: Withers
authors.affiliation: Department of Pathology and Infectious Diseases, The Royal Veterinary College, Centre for Emerging, Endemic and Exotic Disease, Hawkshead Lane, Hertfordshire, AL9 7TA, UK.
authors.forename: Annemieke
authors.initials: A
authors.lastname: Ten Bokum
authors.affiliation: Laboratory of Structural Biology and Maurice Wilkins Centre for Molecular Biodiscovery, School of Biological Sciences, University of Auckland, New Zealand.
authors.forename: J Shaun
authors.initials: JS
authors.lastname: Lott
authors.affiliation: Laboratory of Structural Biology and Maurice Wilkins Centre for Molecular Biodiscovery, School of Biological Sciences, University of Auckland, New Zealand.
authors.forename: Chen
authors.initials: C
authors.lastname: Gao
authors.affiliation: Department of Environmental Biology, Centro de Investigaciones Biológicas-Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain.
authors.forename: Iria
authors.initials: I
authors.lastname: Uhia-Castro
authors.affiliation: Department of Pathology and Infectious Diseases, The Royal Veterinary College, Centre for Emerging, Endemic and Exotic Disease, Hawkshead Lane, Hertfordshire, AL9 7TA, UK.
authors.forename: Neil G
authors.initials: NG
authors.lastname: Stoker
mesh_terms: D020816:Amino Acid Motifs; D001426:Bacterial Proteins / Q000502:physiology*; D001665:Binding Sites; D002784:Cholesterol / Q000378:metabolism*; D017124:Conserved Sequence; D005786:Gene Expression Regulation; D055029:Inverted Repeat Sequences; D009161:Mycobacterium / Q000235:genetics / Q000378:metabolism; D020102:Mycobacterium smegmatis / Q000235:genetics / Q000378:metabolism*; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic; D018085:Regulon; D012097:Repressor Proteins / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013045:Species Specificity
chemical_list: D001426:Bacterial Proteins; D012097:Repressor Proteins; D002784:Cholesterol