Targeting Mycobacterium tuberculosis and Other Microbial Pathogens Using Improved Synthetic Antibacterial Peptides

ABSTRACTThe lack of effective therapies for treating tuberculosis (TB) is a global health problem. WhileMycobacterium tuberculosisis notoriously resistant to most available antibiotics, we identified synthetic short cationic antimicrobial peptides that were active at low micromolar concentrations (less than 10 μM). These small peptides (averaging 10 amino acids) had remarkably broad spectra of antimicrobial activities against both bacterial and fungal pathogens and an indication of low cytotoxicity. In addition, their antimicrobial activities displayed various degrees of species specificity that were not related to taxonomy. For example,Candida albicansandStaphylococcus aureuswere the best surrogates to predict peptide activity againstM. tuberculosis, whileMycobacterium smegmatiswas a poor surrogate. Principle component analysis of activity spectrum profiles identified unique features associated with activity againstM. tuberculosisthat reflect their distinctive amino acid composition; active peptides were more hydrophobic and cationic, reflecting increased tryptophan with compensating decreases in valine and other uncharged amino acids and increased lysine. These studies provide foundations for development of cationic antimicrobial peptides as potential new therapeutic agents for TB treatment.

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Combined Bioinformatic and Rational Design Approach To Develop Antimicrobial Peptides against Mycobacterium tuberculosis

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00940-15 ◽

2016 ◽

Vol 60 (5) ◽

pp. 2757-2764 ◽

Cited By ~ 8

Author(s):

C. Seth Pearson ◽

Zachary Kloos ◽

Brian Murray ◽

Ebot Tabe ◽

Monica Gupta ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

Antimicrobial Peptides ◽

Rational Design ◽

Pathogenic Bacteria ◽

First Generation ◽

De Novo ◽

Specific Activity ◽

Lung Epithelial Cells ◽

Content Type ◽

Low Cytotoxicity

ABSTRACTDrug-resistant pathogens are a growing problem, and novel strategies are needed to combat this threat. Among the most significant of these resistant pathogens isMycobacterium tuberculosis, which is an unusually difficult microbial target due to its complex membrane. Here, we design peptides for specific activity againstM. tuberculosisusing a combination of “database filtering” bioinformatics, protein engineering, andde novodesign. Several variants of these peptides are structurally characterized to validate the design process. The designed peptides exhibit potent activity (MIC values as low as 4 μM) againstM. tuberculosisand also exhibit broad activity against a host of other clinically relevant pathogenic bacteria such as Gram-positive bacteria (Streptococcus) and Gram-negative bacteria (Escherichia coli). They also display excellent selectivity, with low cytotoxicity against cultured macrophages and lung epithelial cells. These first-generation antimicrobial peptides serve as a platform for the design of antibiotics and for investigating structure-activity relationships in the context of theM. tuberculosismembrane. The antimicrobial peptide design strategy is expected to be generalizable for any pathogen for which an activity database can be created.

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Cationic Antimicrobial Peptides for Tuberculosis: A Mini-Review

Current Protein and Peptide Science ◽

10.2174/1389203720666190626160057 ◽

2019 ◽

Vol 20 (9) ◽

pp. 885-892

Author(s):

Sara Silva ◽

Nuno Vale

Keyword(s):

Mycobacterium Tuberculosis ◽

Amino Acid ◽

Antimicrobial Peptides ◽

Resistance Mechanisms ◽

Therapeutic Agents ◽

Pharmacological Properties ◽

Therapeutic Activity ◽

Alternative Strategies ◽

Cationic Antimicrobial Peptides ◽

Specific Amino Acid

Cationic antimicrobial peptides (CAMPs) can be considered as new potential therapeutic agents for Tuberculosis treatment with a specific amino acid sequence. New studies can be developed in the future to improve the pharmacological properties of CAMPs and also understand possible resistance mechanisms. This review discusses the principal properties of natural and/or synthetic CAMPs, and how these new peptides have a significant specificity for Mycobacterium tuberculosis. Also, we propose some alternative strategies to enhance the therapeutic activity of these CAMPs that include coadministration with nanoparticles and/or classic drugs.

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Bordetella pertussis Lipid A Glucosamine Modification Confers Resistance to Cationic Antimicrobial Peptides and Increases Resistance to Outer Membrane Perturbation

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02590-14 ◽

2014 ◽

Vol 58 (8) ◽

pp. 4931-4934 ◽

Cited By ~ 19

Author(s):

Nita R. Shah ◽

Robert E. W. Hancock ◽

Rachel C. Fernandez

Keyword(s):

Immune System ◽

Antimicrobial Peptides ◽

Outer Membrane ◽

Bordetella Pertussis ◽

Lipid A ◽

Whooping Cough ◽

Human Immune System ◽

Cationic Antimicrobial Peptides ◽

Content Type ◽

Membrane Perturbation

ABSTRACTBordetella pertussis, the causative agent of whooping cough, has many strategies for evading the human immune system. Lipopolysaccharide (LPS) is an important Gram-negative bacterial surface structure that activates the immune system via Toll-like receptor 4 and enables susceptibility to cationic antimicrobial peptides (CAMPs). We show modification of the lipid A region of LPS with glucosamine increased resistance to numerous CAMPs, including LL-37. Furthermore, we demonstrate that this glucosamine modification increased resistance to outer membrane perturbation.

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Biochemical and functional characterization of Mycobacterium tuberculosis ketol-acid reductoisomerase

Microbiology ◽

10.1099/mic.0.001087 ◽

2021 ◽

Vol 167 (9) ◽

Author(s):

Nirbhay Singh ◽

Anu Chauhan ◽

Ram Kumar ◽

Sudheer Kumar Singh

Keyword(s):

Amino Acids ◽

Mycobacterium Tuberculosis ◽

Type Species ◽

Low Ph ◽

Stress Conditions ◽

Starvation Stress ◽

Content Type ◽

E Coli ◽

Link Type

Branched-chain amino acids (BCAAs) are essential amino acids, but their biosynthetic pathway is absent in mammals. Ketol-acid reductoisomerase (IlvC) is a BCAA biosynthetic enzyme that is coded by Rv3001c in Mycobacterium tuberculosis H37Rv (Mtb-Rv) and MRA_3031 in M. tuberculosis H37Ra (Mtb-Ra). IlvCs are essential in Mtb-Rv as well as in Escherichia coli . Compared to wild-type and IlvC-complemented Mtb-Ra strains, IlvC knockdown strain showed reduced survival at low pH and under low pH+starvation stress conditions. Further, increased expression of IlvC was observed under low pH and starvation stress conditions. Confirmation of a role for IlvC in pH and starvation stress was achieved by developing E. coli BL21(DE3) IlvC knockout, which was defective for growth in M9 minimal medium, but growth could be rescued by isoleucine and valine supplementation. Growth was also restored by complementing with over-expressing constructs of Mtb-Ra and E. coli IlvCs. The E. coli knockout also had a survival deficit at pH=5.5 and 4.5 and was more susceptible to killing at pH=3.0. The biochemical characterization of Mtb-Ra and E. coli IlvCs confirmed that both have NADPH-dependent activity. In conclusion, this study demonstrates the functional complementation of E. coli IlvC by Mtb-Ra IlvC and also suggests that IlvC has a role in tolerance to low pH and starvation stress.

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Synthesis and Biological Studies of Dodecameric Cationic Antimicrobial Peptides Containing Tetrahydrofuran Amino Acids

ChemBioChem ◽

10.1002/cbic.202000163 ◽

2020 ◽

Vol 21 (17) ◽

pp. 2518-2526

Author(s):

Uttam Ghosh ◽

Isha Soni ◽

Grace Kaul ◽

Priyanka Trivedi ◽

Vinita Chaturvedi ◽

...

Keyword(s):

Amino Acids ◽

Antimicrobial Peptides ◽

Cationic Antimicrobial Peptides ◽

Biological Studies

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Design and Synthesis of New Cationic Antimicrobial Peptides with Low Cytotoxicity

International Journal of Peptide Research and Therapeutics ◽

10.1007/s10989-020-10133-4 ◽

2020 ◽

Author(s):

Pengbi Liu ◽

Xiaomei Zeng ◽

Xuejun Wen

Keyword(s):

Antimicrobial Peptides ◽

Cationic Antimicrobial Peptides ◽

Design And Synthesis ◽

Low Cytotoxicity

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Rational Design of Engineered Cationic Antimicrobial Peptides Consisting Exclusively of Arginine and Tryptophan, and Their Activity against Multidrug-Resistant Pathogens

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02218-12 ◽

2013 ◽

Vol 57 (6) ◽

pp. 2511-2521 ◽

Cited By ~ 83

Author(s):

Berthony Deslouches ◽

Jonathan D. Steckbeck ◽

Jodi K. Craigo ◽

Yohei Doi ◽

Timothy A. Mietzner ◽

...

Keyword(s):

Antimicrobial Peptides ◽

Rational Design ◽

Antimicrobial Agents ◽

Divalent Cations ◽

Multidrug Resistant ◽

Resistance Mechanisms ◽

Broth Culture ◽

Cationic Antimicrobial Peptides ◽

Content Type ◽

Amphipathic Helices

ABSTRACTThe emergence of multidrug-resistant (MDR) pathogens underscores the need for new antimicrobial agents to overcome the resistance mechanisms of these organisms. Cationic antimicrobial peptides (CAPs) provide a potential source of new antimicrobial therapeutics. We previously characterized a lytic base unit (LBU) series of engineered CAPs (eCAPs) of 12 to 48 residues demonstrating maximum antibacterial selectivity at 24 residues. Further, Trp substitution in LBU sequences increased activity against bothP. aeruginosaandS. aureusunder challenging conditions (e.g., saline, divalent cations, and serum). Based on these findings, we hypothesized that the optimal length and, therefore, the cost for maximum eCAP activity under physiologically relevant conditions could be significantly reduced using only Arg and Trp arranged to form idealized amphipathic helices. Hence, we developed a novel peptide series, composed only of Arg and Trp, in a sequence predicted and verified by circular dichroism to fold into optimized amphipathic helices. The most effective antimicrobial activity was achieved at 12 residues in length (WR12) against a panel of both Gram-negative and Gram-positive clinical isolates, including extensively drug-resistant strains, in saline and broth culture and at various pH values. The results demonstrate that the rational design of CAPs can lead to a significant reduction in the length and the number of amino acids used in peptide design to achieve optimal potency and selectivity against specific pathogens.

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Role of the LytSR Two-Component Regulatory System in Adaptation to Cationic Antimicrobial Peptides in Staphylococcus aureus

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00412-13 ◽

2013 ◽

Vol 57 (8) ◽

pp. 3875-3882 ◽

Cited By ~ 24

Author(s):

Soo-Jin Yang ◽

Yan Q. Xiong ◽

Michael R. Yeaman ◽

Kenneth W. Bayles ◽

Wessam Abdelhady ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Antimicrobial Peptides ◽

Regulatory System ◽

Target Tissue ◽

Adaptive Responses ◽

Cationic Antimicrobial Peptide ◽

Cationic Antimicrobial Peptides ◽

Content Type ◽

Response System ◽

Two Component

ABSTRACTMany host defense cationic antimicrobial peptides (HDPs) perturb the staphylococcal cell membrane (CM) and alter transmembrane potential (ΔΨ) as key parts of their lethal mechanism. Thus, a sense-response system for detecting and mediating adaptive responses to such stresses could impact organism survival; theStaphylococcus aureusLytSR two-component regulatory system (TCRS) may serve as such a ΔΨ sensor. One well-known target of this system is thelrgABoperon, which, along with the relatedcidABCoperon, has been shown to be a regulator in the control of programmed cell death and lysis. We used an isogenic set ofS. aureusstrains: (i) UAMS-1, (ii) its isogenic ΔlytSand ΔlrgABmutants, and (iii) plasmid-complemented ΔlytSRand ΔlrgABmutants. The ΔlytSstrain displayed significantly increasedin vitrosusceptibilities to all HDPs tested (neutrophil-derived human neutrophil peptide 1 [hNP-1], platelet-derived thrombin-induced platelet microbicidal proteins [tPMPs], and the tPMP-mimetic peptide RP-1), as well as to calcium-daptomycin (DAP), a cationic antimicrobial peptide (CAP). In contrast, the ΔlrgABstrain exhibited no significant changes in susceptibilities to these cationic peptides, indicating that althoughlytSRpositively regulates transcription oflrgAB, increased HDP/CAP susceptibilities in the ΔlytSmutant werelrgABindependent. Further, parental UAMS-1 (but not the ΔlytSmutant) became more resistant to hNP-1 and DAP following pretreatment with carbonyl cyanidem-chlorophenylhydrazone (CCCP) (a CM-depolarizing agent). Of note,lytSR-dependent survival against CAP/HDP killing was not associated with changes in either surface positive charge, expression ofmprFanddlt, or CM fluidity. The ΔlytSstrain (but not the ΔlrgABmutant) displayed a significant reduction in target tissue survival in an endocarditis model during DAP treatment. Collectively, these results suggest that thelytSRTCRS plays an important role in adaptive responses ofS. aureusto CM-perturbing HDPs/CAPs, likely by functioning as a sense-response system for detecting subtle changes in ΔΨ.

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