scholarly journals A screen of covalent inhibitors in Mycobacterium tuberculosis identifies serine hydrolases involved in lipid metabolism as potential therapeutic targets

2021 ◽  
Author(s):  
Brett M. Babin ◽  
Laura J. Keller ◽  
Yishay Pinto ◽  
Veronica L Li ◽  
Andrew Eneim ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Cell Envelope ◽  
Protein Profiling ◽  
Serine Hydrolases ◽  
Antibiotic Resistant ◽  
Competitive Activity ◽  
Covalent Inhibitors ◽  
New Antibiotics ◽  
Effective Therapeutic Strategy ◽  
Simultaneous Inhibition

The increasing incidence of antibiotic-resistant Mycobacterium tuberculosis infections is a global health threat necessitating the development of new antibiotics. Serine hydrolases (SHs) are a promising class of targets because of their importance for the synthesis of the mycobacterial cell envelope. We screened a library of small molecules containing serine-reactive electrophiles and identified narrow spectrum inhibitors of M. tuberculous growth. Using these lead molecules, we performed competitive activity-based protein profiling and identified multiple SH targets, including enzymes with uncharacterized functions. Lipidomic analyses of compound-treated cultures revealed an accumulation of free lipids and a substantial decrease in lipooligosaccharides, linking SH inhibition to defects in cell envelope biogenesis. Mutant analysis revealed a path to resistance via the synthesis of mycocerates, but not through mutations to target enzymes. Our results suggest that simultaneous inhibition of multiple SH enzymes is likely to be an effective therapeutic strategy for the treatment of M. tuberculosis infections.

scholarly journals Comparative Tn-Seq reveals common daptomycin resistance determinants in Staphylococcus aureus despite strain-dependent differences in essentiality of shared cell envelope genes

2019 ◽  
Author(s):  
Kathryn A. Coe ◽  
Wonsik Lee ◽  
Gloria Komazin-Meredith ◽  
Timothy C. Meredith ◽  
Yonatan H. Grad ◽  
...  
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
Cell Envelope ◽  
The United States ◽  
Resistance Mechanisms ◽  
Essential Genes ◽  
Next Generation ◽  
Antibiotic Resistant ◽  
New Antibiotics ◽  
Strain Dependent

AbstractAntibiotic-resistant Staphylococcus aureus remains a leading cause of antibiotic resistance-associated mortality in the United States. Given the reality of multi-drug resistant infections, it is imperative that we establish and maintain a pipeline of new compounds to replace or supplement our current antibiotics. A first step towards this goal is to prioritize targets by identifying the genes most consistently required for survival across the S. aureus phylogeny. Here we report the first direct comparison of gene essentiality across multiple strains of S. aureus via transposon sequencing. We show that mutant fitness varies by strain in key pathways, underscoring the importance of using more than one strain to differentiate between core and strain-dependent essential genes. Despite baseline differences in gene importance, several pathways, including the lipoteichoic acid pathway, become consistently essential under daptomycin exposure, suggesting core vulnerabilities that can be exploited to resensitize daptomycin-nonsusceptible isolates. We also demonstrate the merit of using transposons with outward-facing promoters capable of overexpressing nearby genes for identifying clinically-relevant gain-of-function resistance mechanisms. Together, the daptomycin vulnerabilities and resistance mechanisms support a mode of action with wide-ranging effects on the cell envelope and cell division. This work adds to a growing body of literature demonstrating the nuanced insights gained by comparing Tn-Seq results across multiple bacterial strains.Author summaryAntibiotic-resistant Staphylococcus aureus kills thousands of people every year in the United States alone. To stay ahead of the looming threat of multidrug-resistant infections, we must continue to develop new antibiotics and find ways of making our current repertoire of antibiotics more effective, including by finding pairs of compounds that perform best when administered together. In the age of next-generation sequencing, we can now use transposon sequencing to find potential targets for new antibiotics on a genome-wide scale, identified as either essential genes or genes that become essential in the presence of an antibiotic. In this work, we created a compendium of genes that are essential across a range of S. aureus strains, as well as those that are essential in the presence of the antibiotic daptomycin. The results will be a resource for researchers working to develop the next generation of antibiotic therapies.

scholarly journals A competitive activity-based protein profiling platform yields cell wall synthesis inhibitors active against replicating and non-replicating Mycobacterium tuberculosis

2021 ◽  
Author(s):  
Michael Li ◽  
Hiren V. Patel ◽  
Armand B. Cognetta ◽  
Trever C. Smith ◽  
Ivy Mallick ◽  
...  
Keyword(s):  
Cell Wall ◽  
Mycobacterium Tuberculosis ◽  
Biological Activity ◽  
Protein Profiling ◽  
Computational Docking ◽  
Competitive Activity ◽  
Form Part ◽  
Major Bottleneck ◽  
Potential False Positive ◽  
Activity Series

ABSTRACTThe identification and validation of a small molecule’s targets is a major bottleneck in the discovery process for tuberculosis antibiotics. Activity-based protein profiling (ABPP) is an efficient tool for determining a small molecule’s targets within complex proteomes. However, how target inhibition relates to biological activity is often left unexplored. Here we studied the effects of 1,2,3-triazole ureas on Mycobacterium tuberculosis (Mtb). After screening ~200 compounds, we focused on two inhibitors active against both exponentially replicating and hypoxia-induced drug-tolerant Mtb that form part of a four-compound structure-activity series. The compound with negligible activity revealed potential false positive targets not addressed in other ABPP studies. Biochemistry, computational docking, and morphological analysis confirmed that active compounds preferentially inhibit serine hydrolases with cell wall and lipid metabolism functions and that disruption of the cell wall underlies biological activity. Our findings showed that ABPP identifies the targets most likely relevant to a compound’s antibacterial activity.

scholarly journals The tryptophan biosynthetic pathway is essential for Mycobacterium tuberculosis to cause disease

2020 ◽  
Vol 48 (5) ◽  
pp. 2029-2037
Author(s):  
J. Shaun Lott
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Biosynthetic Pathway ◽  
Infectious Agent ◽  
Tryptophan Biosynthesis ◽  
Bacterial Survival ◽  
Antibiotic Resistant ◽  
Resistant Disease ◽  
New Therapeutic Approaches ◽  
Long Duration ◽  
New Antibiotics

Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), is the most significant cause of death from a single infectious agent worldwide. Antibiotic-resistant strains of M. tuberculosis represent a threat to effective treatment, and the long duration, toxicity and complexity of current chemotherapy for antibiotic-resistant disease presents a need for new therapeutic approaches with novel modes of action. M. tuberculosis is an intracellular pathogen that must survive phagocytosis by macrophages, dendritic cells or neutrophils to establish an infection. The tryptophan biosynthetic pathway is required for bacterial survival in the phagosome, presenting a target for new classes of antitubercular compound. The enzymes responsible for the six catalytic steps that produce tryptophan from chorismate have all been characterised in M. tuberculosis, and inhibitors have been described for some of the steps. The innate immune system depletes cellular tryptophan in response to infection in order to inhibit microbial growth, and this effect is likely to be important for the efficacy of tryptophan biosynthesis inhibitors as new antibiotics. Allosteric inhibitors of both the first and final enzymes in the pathway have proven effective, including by a metabolite produced by the gut biota, raising the intriguing possibility that the modulation of tryptophan biosynthesis may be a natural inter-bacterial competition strategy.

scholarly journals Characterization of Novel Mycobacterium tuberculosis and Mycobacterium smegmatis Mutants Hypersusceptible to β-Lactam Antibiotics

2005 ◽  
Vol 187 (6) ◽  
pp. 1892-1900 ◽  
Author(s):  
Anthony R. Flores ◽  
Linda M. Parsons ◽  
Martin S. Pavelka
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Mycobacterium Smegmatis ◽  
Cell Envelope ◽  
Novel Genes ◽  
Antibiotic Resistant ◽  
Peptidoglycan Biosynthesis ◽  
Isolation And Characterization ◽  
Lactam Antibiotic ◽  
Transposon Mutants

ABSTRACT Our laboratory previously constructed mutants of Mycobacterium tuberculosis and Mycobacterium smegmatis with deletions in the genes for their major β-lactamases, BlaC and BlaS, respectively, and showed that the mutants have increased susceptibilities to most β-lactam antibiotics, particularly the penicillins. However, there is still a basal level of resistance in the mutants to certain penicillins, and the susceptibilities of the mutants to some cephalosporin-based β-lactams are essentially the same as those of the wild types. We hypothesized that characterizing additional mutants (derived from β-lactamase deletion mutants) that are hypersusceptible to β-lactam antibiotics might reveal novel genes involved with other mechanisms of β-lactam resistance, peptidoglycan assembly, and cell envelope physiology. We report here the isolation and characterization of nine β-lactam antibiotic-hypersusceptible transposon mutants, two of which have insertions in genes known to be involved with peptidoglycan biosynthesis (ponA2 and dapB); the other seven mutants have insertions which affect novel genes. These genes can be classified into three groups: those involved with peptidoglycan biosynthesis, cell division, and other cell envelope processes. Two of the peptidoglycan-biosynthetic genes (ponA2 and pbpX) may encode β-lactam antibiotic-resistant enzymes proposed to be involved with the synthesis of the unusual diaminopimelyl linkages within the mycobacterial peptidoglycan.

Exploration of Ion Channels in Mycobacterium tuberculosis: Implication on Drug Discovery and Potent Drug Targets Against Tuberculosis

2020 ◽  
Vol 14 (1) ◽  
pp. 14-29
Author(s):  
Manish Dwivedi
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Drug Targets ◽  
Cell Envelope ◽  
Intracellular Pathogen ◽  
Host Immune System ◽  
Transporter Proteins ◽  
Channel Proteins ◽  
Medical Importance ◽  
Potent Drug ◽  
Emergence Of Resistance

Scientific interest in mycobacteria has been sparked by the medical importance of Mycobacterium tuberculosis (Mtb) that is known to cause severe diseases in mammals, i.e. tuberculosis and by properties that distinguish them from other microorganisms which are notoriously difficult to treat. The treatment of their infections is difficult because mycobacteria fortify themselves with a thick impermeable cell envelope. Channel and transporter proteins are among the crucial adaptations of Mycobacterium that facilitate their strength to combat against host immune system and anti-tuberculosis drugs. In previous studies, it was investigated that some of the channel proteins contribute to the overall antibiotic resistance in Mtb. Moreover, in some of the cases, membrane proteins were found responsible for virulence of these pathogens. Given the ability of M. tuberculosis to survive as an intracellular pathogen and its inclination to develop resistance to the prevailing anti-tuberculosis drugs, its treatment requires new approaches and optimization of anti-TB drugs and investigation of new targets are needed for their potential in clinical usage. Therefore, it is imperative to investigate the survival of Mtb. in stressed conditions with different behavior of particular channel/ transporter proteins. Comprehensive understanding of channel proteins and their mechanism will provide us direction to find out preventive measures against the emergence of resistance and reduce the duration of the treatment, eventually leading to plausible eradication of tuberculosis.

scholarly journals 833. Characteristics and Utilization Patterns of Colistin Compared with Newer Agents in Gram-Negative Infections

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S457-S457
Author(s):  
Stephen Marcella ◽  
Casey Doremus ◽  
Roger Echols
Keyword(s):  
Patient Characteristics ◽  
Total Hospital Cost ◽  
Healthcare Database ◽  
New Agents ◽  
Antibiotic Resistant ◽  
Gram Negative ◽  
Days Of Therapy ◽  
New Antibiotics ◽  
The Usa ◽  
Utilization Patterns

Abstract Background Colistin has resurfaced in light of Gram-negative (GN) resistance. New antibiotics to treat antibiotic resistant GN infections (eg, ceftazidime-avibactam, ceftolozane-tazobactam, meropenem-vaborbactam [new agents]), have recently been approved but their use vs colistin is unclear. We compared the overall use of colistin and new agents from 2014 to 2018 in patient days on therapy (PDOT). Methods Data on non-cystic fibrosis patients from the Premier Healthcare Database was used. PDOT was tabulated quarterly for Premier hospitals and projected to the US population. A subset of data from 2016 to 2018 with microbiologically confirmed GN (MCGN) infections was selected for adult inpatients receiving ≥3 days of therapy with colistin, new agents, carbapenems, or extended-spectrum cephalosporins. The index infection was defined either as the first carbapenem-resistant (CR) or -sensitive infection if no CR infection occurred. Patients could be treated with ≥1 antibiotic per infection. Utilization was examined by pathogen and patient characteristics. Results PDOT with colistin decreased from 2015 to 2018, while new agents have increased (Figure). During 2015–2018, colistin and any of 3 new agents were used by 3,320 and 5,781 inpatients, respectively, of whom, 649 (20%) and 1,284 (22%) had MCGN pathogens. Colistin-treated patients were sicker than patients treated with new agents (Table), underlying renal disease was present in 34.5% vs 36.3 %, and median length of stay of 17 vs 15 days, respectively. Mean total hospital cost was $93,815 vs $84,013 for colistin and new agents, respectively. Mortality was greater in colistin patients (18% vs 12%; p< 0.0001). CR infections constituted similar proportions of colistin and new agent use (79% vs 75%). Colistin accounted for 15.2% of CR Acinetobacter treatments and 9.7% of CR Enterobacterales (CRE) treatments compared with 4.5% and 12.8%, respectively, for new agents. Figure. Projected Inpatient PDOT Table. Conclusion Colistin use has decreased simultaneously with the introduction and increased use of new agents in the USA. Colistin was used more frequently in sicker patients and for Acinetobacter spp. infections than for CRE infections. Patients on colistin have worse outcomes, probably due to baseline differences in their health status. Disclosures Stephen Marcella, MD, Shionogi Inc. (Employee) Casey Doremus, MS, Shionogi Inc. (Employee) Roger Echols, MD, Shionogi Inc. (Consultant)

scholarly journals Antibiotic Pipeline Coordinators

2018 ◽  
Vol 46 (S1) ◽  
pp. 25-31 ◽  
Author(s):  
Enrico Baraldi ◽  
Olof Lindahl ◽  
Miloje Savic ◽  
David Findlay ◽  
Christine Årdal
Keyword(s):  
Research And Development ◽  
World Health ◽  
Resistant Bacteria ◽  
Antibiotic Resistant ◽  
Priority List ◽  
Non Profit ◽  
Global Priority ◽  
The World ◽  
New Antibiotics ◽  
Health Organization

The World Health Organization (WHO) has published a global priority list of antibiotic-resistant bacteria to guide research and development (R&D) of new antibiotics. Every pathogen on this list requires R&D activity, but some are more attractive for private sector investments, as evidenced by the current antibacterial pipeline. A “pipeline coordinator” is a governmental/non-profit organization that closely tracks the antibacterial pipeline and actively supports R&D across all priority pathogens employing new financing tools.

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