Deciphering the Transcriptional Regulation of Cholesterol Catabolic Pathway in Mycobacteria

García-Fernández, Esther; Medrano, F.J.; Galán, Beatriz; Garcı́a, José Luis

doi:10.1074/jbc.m113.545715

Cited by 35 publications

(46 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It seems unlikely that the two KstR orthologs have different effectors considering that they share 87% amino acid sequence identity, including the four residues predicted to interact with the CoA moiety. Indeed, Garcia-Fernandez et al (43) recognized the possibility that the physiological effector of KstR is a CoA thioester but were unable to test this hypothesis.…”

Section: Discussionmentioning

confidence: 99%

“…Nevertheless, the role of a cholesten-26-oyl-CoA as the effector of KstR Mtb would mirror the regulatory logic of the KstR2 regulon in M. tuberculosis in that the catabolic genes are induced by the first CoA thioester catabolite produced. Interestingly, 3-oxo-4-cholesten-26-oic acid was identified as the effector of KstR of Mycobacterium smegmatis (43). It seems unlikely that the two KstR orthologs have different effectors considering that they share 87% amino acid sequence identity, including the four residues predicted to interact with the CoA moiety.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Structural and Functional Characterization of a Ketosteroid Transcriptional Regulator of Mycobacterium tuberculosis

Crowe¹,

Stogios

Casabon

et al. 2015

Journal of Biological Chemistry

View full text Add to dashboard Cite

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Structural and Functional Characterization of a Ketosteroid Transcriptional Regulator of Mycobacterium tuberculosis

Crowe¹,

Stogios

Casabon

et al. 2015

Journal of Biological Chemistry

View full text Add to dashboard Cite

“…KstR2 regulates the transcription of genes encoding C/D ring degrading enzymes. The regulators are derepressed by CoA metabolites in the pathway (12,13). We found that none of these genes are required for potentiating INH activity by 4a against Mtb when grown with either cholesterol or glycerol as the carbon source (Table 2).…”

Section: -Azasteroids Are Synergistic With Inh or Bdqmentioning

confidence: 88%

“…At least 52 cholesterolregulated genes are clustered within the "Cho-region" of the Mtb genome and encode the requisite enzymes needed for catabolism (2,8). Two TetR family regulators: KstR1 and KstR2 control transcription of the majority of these catabolism genes (10,11) and are derepressed by coenzyme-A (CoA) metabolites of the catabolism pathway (12,13).…”

Section: Introductionmentioning

confidence: 99%

The Mce3R Regulon Is Required for 6-Azasteroid Potentiation of Anti-TB Drug Activity

Yang¹,

Yuan²,

Ma³

et al. 2018

Preprint

View full text Add to dashboard Cite

Mycobacterium tuberculosis (Mtb) infects humans and can live dormant within macrophages for decades, residing in a granuloma structure that arises from the host immune response and cholesterol is important for Mtb persistence in the host. Disruption of cholesterol-regulated genes results in reduced intracellular Mtb survival in animal models of infection. We phenotypically screened approximately 50 6-azasteroids against Mtb. We selected this steroid scaffold for its advantageous biophysical and pharmacokinetic properties. We found that at low micromolar concentrations a subset of 6-azasteroids sensitizes Mtb to the TB drug isoniazid and reduces the isoniazid MIC 15-30-fold. Two analogs selected for further study analogously sensitize Mtb to bedaquiline, and they improve the bactericidal activity of bedaquiline and isoniazid. Both 6-azasteroids improve the efficacy of isoniazid and bedaquiline under conditions of low oxygen, and demonstrate high synergy with bedaquiline (FIC index = 0.21, MIC BDQ = 16 nM at 1 µM 6-azasteroid). The rate of spontaneous resistance to 6-azasteroid is approximately 10 -7 and the 6-azasteroid resistance mutants retain their sensitivity to isoniazid and bedaquiline. Intriguingly, genes in the cholesterol-regulated Mce3R regulon are required for 6-azasteroid activity and genes in the cholesterol catabolism pathway are not. The Mce3R regulon has been implicated in stress resistance, and is not present in saprophytic strains of mycobacteria. We conclude that the Mce3R regulon encodes a cholesterol-dependent pathway important for pathogenesis that contributes to drug tolerance. Small molecule strategies to target the Mce3R regulon present an attractive avenue for further development of co-drugs that can improve existing tuberculosis chemotherapies. SIGNIFICANCEOne third of the world's population carries the infectious agent Mycobacterium tuberculosis (Mtb) that causes tuberculosis (TB), and every 17 seconds someone dies of TB worldwide. TB is the number one cause of death from a bacterial infectious disease. Current treatments require drug regimens of long duration to effectively cure TB disease and have many associated toxicities that are compounded by the high doses of long duration required. We have identified small molecules that increase Mtb susceptibility to existing TB drugs. The target of these small molecules is a pathway important for resistance of Mtb to stress. Development of a co-drug therapy has the potential to shorten treatment times and reduce toxicities associated with treatment of TB.

show abstract

“…The unusually large regulon of KstR (74 genes in M. tuberculosis) and the presence of genes within it that are involved in growth on palmitate suggest that the repressor may also control the metabolism of lipids other than just cholesterol (13) and is therefore likely to be induced by more than one compound. In the first investigation of possible cognate ligands for KstR in Mycobacterium smegmatis, García-Fernández et al (19) determined that cholesterol and cholest-4-en-3-one, the entry compound and initial metabolite of the pathway (Fig. 1), respectively, were unable to induce the release of KstR from its operator.…”

mentioning

confidence: 99%

The Structure of the Transcriptional Repressor KstR in Complex with CoA Thioester Cholesterol Metabolites Sheds Light on the Regulation of Cholesterol Catabolism in Mycobacterium tuberculosis

Dawes

Crowe³

et al. 2016

Journal of Biological Chemistry

View full text Add to dashboard Cite

Cholesterol can be a major carbon source for Mycobacterium tuberculosis during infection, both at an early stage in the macrophage phagosome and later within the necrotic granuloma. KstR is a highly conserved TetR family transcriptional repressor that regulates a large set of genes responsible for cholesterol catabolism. Many genes in this regulon, including kstR, are either induced during infection or are essential for survival of M. tuberculosis in vivo. In this study, we identified two ligands for KstR, both of which are CoA thioester cholesterol metabolites with four intact steroid rings. A metabolite in which one of the rings was cleaved was not a ligand. We confirmed the ligand-protein interactions using intrinsic tryptophan fluorescence and showed that ligand binding strongly inhibited KstR-DNA binding using surface plasmon resonance (IC 50 for Tuberculosis remains a global threat to human health due to the emergence of extremely drug-resistant forms of Mycobacterium tuberculosis and co-infection with HIV (1). Elucidation of metabolic networks essential to the pathogenesis of M. tuberculosis is an important part of the quest to identify new drug target candidates that can be exploited to tackle extremely drug-resistant tuberculosis. In particular, M. tuberculosis possesses an unusual ability to metabolize lipids, and its genome is heavily orientated toward this task with the involvement of a remarkable number of genes, ϳ250, constituting around 6% of its genome (2).Cholesterol, the dominant lipid accumulated in M. tuberculosis-induced foamy macrophages, is a key growth substrate for M. tuberculosis in the intraphagosomal environment and is also important to the bacterium in necrotizing granulomas in late stage infection (3-5). M. tuberculosis is capable of utilizing cholesterol as a sole carbon source for both energy synthesis and assimilation into membrane lipids (3, 6). Many genes in the cholesterol degradation pathway are up-regulated or are essential for M. tuberculosis infection in various models of disease (3,4,(7)(8)(9)(10)(11). Disruption of genes encoding cholesterol catabolic enzymes, either through genetic manipulation or chemically, inhibits growth of the bacterium in both macrophage and animal models, and in vitro experiments suggest that this growth inhibition may be due to the toxicity of accumulated intermediates (4, 9, 12).The cholesterol degradation pathway is regulated by two TFRs, 7 KstR and KstR2 (13,14). These regulate two distinct regulons and negatively autoregulate their own expression. KstR regulates the expression of the genes involved in the trans-

show abstract

Deciphering the Transcriptional Regulation of Cholesterol Catabolic Pathway in Mycobacteria

Cited by 35 publications

References 53 publications

Structural and Functional Characterization of a Ketosteroid Transcriptional Regulator of Mycobacterium tuberculosis

Structural and Functional Characterization of a Ketosteroid Transcriptional Regulator of Mycobacterium tuberculosis

The Mce3R Regulon Is Required for 6-Azasteroid Potentiation of Anti-TB Drug Activity

The Structure of the Transcriptional Repressor KstR in Complex with CoA Thioester Cholesterol Metabolites Sheds Light on the Regulation of Cholesterol Catabolism in Mycobacterium tuberculosis

Contact Info

Product

Resources

About