MmpL3 as a Target for the Treatment of Drug-Resistant Nontuberculous Mycobacterial Infections

Li, Wei; Yazidi, Amira; Pandya, Amitkumar N.; Hegde, Pooja; Tong, Weiwei; Moura, Vinicius Calado Nogueira de; North, E. Jeffrey; Sygusch, J.; Jackson, Mary

doi:10.3389/fmicb.2018.01547

Cited by 42 publications

(51 citation statements)

References 49 publications

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“…ICs 5 and 25 target the essential mycolic acid transporter, MmpL3, in MABSC. Previous studies have shown that ICs target the essential mycolic acid transporter MmpL3 (7,9,10,12,14). Here, we report that compounds 5 and 25 target the inner membrane transporter MmpL3 of M. abscessus, resulting in the abolition of the translocation of mycolic acids from the cytoplasm to the periplasmic space, ultimately causing cell death.…”

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confidence: 77%

Indole-2-Carboxamides Are Active against Mycobacterium abscessus in a Mouse Model of Acute Infection

Pandya

Prathipati

Hegde

et al. 2019

Antimicrob Agents Chemother

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Nontuberculous mycobacteria (NTM) pathogens particularly infect patients with structural lung disorders. We previously reported novel indole-2-carboxamides (ICs) that are active against a wide panel of NTM pathogens. This study discloses in vivo data for two lead molecules (compounds 5 and 25) that were advanced for efficacy studies in Mycobacterium abscessus-infected mouse models. Oral administration of the lead molecules showed a statistically significant reduction in the bacterial loads in lung and spleen of M. abscessus-infected mice.

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confidence: 77%

Indole-2-Carboxamides Are Active against Mycobacterium abscessus in a Mouse Model of Acute Infection

Pandya

Prathipati

Hegde

et al. 2019

Antimicrob Agents Chemother

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“…These TMMs are then converted into trehalose dimycolate (TDM) by the Ag85 complex in the cell envelope 18 . MmpL3 is essential as evidenced by a pre-existing rescue allele being required to generate an mmpL3 knockout 2, 14, 17, 19, 20, 21 , lack of mutants in high-throughput transposon mutagenesis screens 22, 23 , and studies that show rapid killing in vitro and in vivo in acute infection models when mmpL3 expression is conditionally inhibited 14, 19 . This makes MmpL3 an attractive target for drug development, with one of its inhibitors, SQ109, currently in clinical trials 24 .…”

Section: Introductionmentioning

confidence: 99%

Identification of new MmpL3 inhibitors by untargeted and targeted mutant screens defines MmpL3 domains with differential resistance

Williams

Haiderer

Coulson

et al. 2019

Preprint

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22combination studies of the inhibitors revealed interactions that were specific to the clades 40 identified in the cross-resistance profiling. Additionally, modeling of resistance substitutions to 41 the MmpL3 crystal structure revealed clade specific localization of the residues to specific 42 domains of MmpL3, with the clades showing differential resistance. Several compounds 43 exhibited high solubility and stability in microsomes and low cytotoxicity in macrophages, 44supporting their further development. The combined study of multiple mutants and novel 45 compounds provides new insights into structure-function interactions of MmpL3 and small 46 molecule inhibitors. 47 the last decade, several of these screens have identified MmpL3 as the proposed target for 53 diverse small molecule inhibitors including AU1235, BM212, C215, DA-5, E11, 54 indolecarboxamides, HC2091, PIPD1, Rimonabant, Spiro, THPP and 55 SQ109 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 . MmpL3 is an essential flippase responsible for transporting 56 acetylated-trehalose monomycolate (TMM) synthesized in the cytoplasm to the pseudo-57 periplasmic space 13, 14, 15, 16, 17 . These TMMs are then converted into trehalose dimycolate (TDM) 58by the Ag85 complex in the cell envelope 18 . MmpL3 is essential as evidenced by a pre-existing 59 rescue allele being required to generate an mmpL3 knockout 2, 14, 17, 19, 20, 21 , lack of mutants in 60 high-throughput transposon mutagenesis screens 22, 23 , and studies that show rapid killing in vitro 61 and in vivo in acute infection models when mmpL3 expression is conditionally inhibited 14, 19 . This 62 makes MmpL3 an attractive target for drug development, with one of its inhibitors, SQ109, 63 currently in clinical trials 24 . 64MmpL3 inhibitors fall into diverse classes of chemical scaffolds 25, 26, 27 , making it hard to 65 computationally predict potential MmpL3 inhibitors based on chemical scaffolds. However, given 66 the frequent finding of MmpL3 as a target, it is reasonable to expect that many new hits in a 67 high throughput screen (HTS) may be acting against MmpL3. MmpL3 inhibitors have been 68 identified by the isolation and sequencing of resistant mutants with single nucleotide variations 69 (SNVs) mapping to the coding region of mmpL3, which is time-consuming and costly. Efforts to 70 discover MmpL3 inhibitors using targeted approaches include generating hypomorphs, where a 71 mmpL3 knock down strain showed enhanced sensitivity to MmpL3 inhibitors, including AU1235 72 14 . However, this strain was also shown to be sensitive to isoniazid (INH) an inhibitor of InhA of 73 the FAS-II pathway involved in mycolic acid synthesis, suggesting that while a mmpL3 74 knockdown strain has robust screening potential for inhibitors of mycolic acid synthesis, 75 maturation, and transport, such strains are not specific enough to identify inhibitors that 76 selectively target MmpL3. 77An alternative approach, employed in this study, is to use a pool of mmpL3 resistant 78 mutants to discover potential MmpL3 ...

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“…These data strongly suggest that compounds from the structural class of benzothiazole cyclohexyl amides such as CRS400153 kill M. abscessus through the direct or indirect inhibition of MmpL3. The fact that CRS400153 showed no effect on the membrane potential and electrochemical pH gradient of Mtb intact cells and inverted membrane vesicles (data not shown) supports a direct mechanism of inhibition of the transporter (Li et al, 2018 ).…”

Section: Resultsmentioning

confidence: 64%

Optimization and Lead Selection of Benzothiazole Amide Analogs Toward a Novel Antimycobacterial Agent

et al. 2018

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Mycobacteria remain an important problem worldwide, especially drug resistant human pathogens. Novel therapeutics are urgently needed to tackle both drug-resistant tuberculosis (TB) and difficult-to-treat infections with nontuberculous mycobacteria (NTM). Benzothiazole adamantyl amide had previously emerged as a high throughput screening hit against M. tuberculosis (Mtb) and was subsequently found to be active against NTM as well. For lead optimization, we applied an iterative process of design, synthesis and screening of several 100 analogs to improve antibacterial potency as well as physicochemical and pharmacological properties to ultimately achieve efficacy. Replacement of the adamantyl group with cyclohexyl derivatives, including bicyclic moieties, resulted in advanced lead compounds that showed excellent potency and a mycobacteria-specific spectrum of activity. MIC values ranged from 0.03 to 0.12 μg/mL against M. abscessus (Mabs) and other rapid- growing NTM, 1–2 μg/mL against M. avium complex (MAC), and 0.12–0.5 μg/mL against Mtb. No pre-existing resistance was found in a collection of n = 54 clinical isolates of rapid-growing NTM. Unlike many antibacterial agents commonly used to treat mycobacterial infections, benzothiazole amides demonstrated bactericidal effects against both Mtb and Mabs. Metabolic labeling provided evidence that the compounds affect the transfer of mycolic acids to their cell envelope acceptors in mycobacteria. Mapping of resistance mutations pointed to the trehalose monomycolate transporter (MmpL3) as the most likely target. In vivo efficacy and tolerability of a benzothiazole amide was demonstrated in a mouse model of chronic NTM lung infection with Mabs. Once daily dosing over 4 weeks by intrapulmonary microspray administration as 5% corn oil/saline emulsion achieved statistically significant CFU reductions compared to vehicle control and non-inferiority compared to azithromycin. The benzothiazole amides hold promise for development of a novel therapeutic agent with broad antimycobacterial activity, though further work is needed to develop drug formulations for direct intrapulmonary delivery via aerosol.

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MmpL3 as a Target for the Treatment of Drug-Resistant Nontuberculous Mycobacterial Infections

Cited by 42 publications

References 49 publications

Indole-2-Carboxamides Are Active against Mycobacterium abscessus in a Mouse Model of Acute Infection

Indole-2-Carboxamides Are Active against Mycobacterium abscessus in a Mouse Model of Acute Infection

Identification of new MmpL3 inhibitors by untargeted and targeted mutant screens defines MmpL3 domains with differential resistance

Optimization and Lead Selection of Benzothiazole Amide Analogs Toward a Novel Antimycobacterial Agent

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