Synthetic Peptides Research Articles

Antifungal peptide-loaded alginate microfiber wound dressing evaluated against Candida albicans in vitro and ex vivo

Invasive fungal infections have high mortality rates, and many current antimycotics are limited by host toxicity and drug resistance. Recent experiments in our laboratory have demonstrated the antifungal activity of dKn2-7, a synthetic peptide, against Candida albicans. The purpose of the current study was to develop a wound dressing capable of dKn2-7 release for extended periods to help combat fungal infection in wounds. dKn2-7 was incorporated into calcium alginate microfibers, an excipient with known wound healing and hemostatic properties. dKn2-7 release rates from the fibers were dependent on drug loading, but all formulations exhibited a burst release with 41–71 % of total release in the first 15 min and 84–96 % release by 24 h. Calcium release at 15 min was similar to that of a commercial hemostatic dressing, indicating dKn2-7 loading would not adversely affect the hemostatic capability of the alginate fibers. In vitro antifungal studies indicated a dose dependent effect with fibers loaded at ≥20 µg/mg causing significant planktonic killing and ≥30 µg/mg causing significant biofilm killing. Viable fungal counts in biofilms grown on ex vivo porcine skin declined by 99 % following 500 µg/mg fiber treatment. Skin histology indicated no significant differences in tissue damage between treatment groups and controls. Results confirm calcium alginate microfibers are capable of binding and subsequently releasing dKn2-7 over a 24-h period when rehydrated. Furthermore, dKn2-7 released from the fibers was able to significantly reduce biofilms in an ex vivo model with minimal toxicity, indicating these dKn2-7 loaded fiber dressings may be effective at controlling C. albicans biofilm infections in vivo.

Epitope profiling of cow's milk allergen-specific antibodies with determining IgE content in epitopes-ALL, a 14-epitopes mixture

Allergen-specific antibodies (Abs), IgE, and IgG4 increase during the early phase of oral immunotherapy (OIT) of allergen food in patients; subsequently, IgE levels decrease and specific IgG4 levels increase after successful OIT treatment. The detailed profile of these Abs during OIT remains largely unclear. We developed a diagnostic tool to assess the OIT efficacy and extent of responsiveness based on a profiling method by identifying epitopes recognized by the Ab classes of IgE or IgG4.A peptide microarray followed by microplate analysis using synthetic peptides was used to identify 14 epitopes widely recognized by IgE and/or IgG4 in the serum samples of patients with OIT among the amino acid sequences of five major cow's milk allergens. The set of defined 14 epitopes clarified different epitope profiles of allergen-specific IgE and IgG4 in each patient's serum samples. Moreover, the total signal of Abs recognizing all 14 epitopes was equal to the sum of all individual epitope-specific Abs. It was further observed that the quantitative value of IgE concentrations of 14 epitopes-ALL correlated with the ImmunoCAP IgE value.These findings strongly imply that the quantity of IgE and IgG4 recognizing epitopes-ALL may easily be used to measure allergy severity. To investigate this potential, we developed an immunochromatographic method that can detect IgE and IgG4 levels in patient samples.This study clearly demonstrated the usefulness of the defined 14 epitopes and their mixture, “epitopes-ALL,” and that the simple and reliable methods of immunochromatography and microplate analyses demonstrating the epitope profile of allergen-specific Abs are applicable for diagnostic use at multiple disease stages and the OIT-treatment course in patients with cow's milk allergy.

The discovery of JAL-TA9 which cleaves amyloid-β with proteolytic activity

Amyloid-β (Aβ) 42, one of the causes of Alzheimer's disease (AD), is produced by the cleavage of amyloid precursor protein (APP) by β- or γ-secretases. Since Aβ42 oligomers exhibit strong neurotoxicity, Aβ42 is predicted to be a potentially efficient target for drug therapies. Recently, we screened peptides that activate MMP7 using our peptide library and found that the synthetic peptide JAL-TA9 (YKGSGFRMI), which is derived from the BoxA region of Tob1 protein, showed proteolytic activity. It is generally accepted that an enzyme should be a large molecular protein consisting of more than thousands of amino acids. Thus, this is the first finding that a small synthetic peptide has protease activity, and we termed Catalytide as the general name of peptides with protease activity. In this study, we demonstrate the cleavage activity of JAL-TA9 not only against the authentic soluble form of Aβ42 but also against the solid type of Aβ42 in the central region. In addition, we demonstrated the cleavage activity using brain slices of AD patients. JAL-TA9 decreased the amount of accumulated Aβ42 in the brain of Alzheimer's patients. Taken together, JAL-TA9 is an attractive seed for the development of peptide drugs with a new strategy for Alzheimer's disease.

Biochemistry, Mechanistic Intricacies, and Therapeutic Potential of Antimicrobial Peptides: An Alternative to Traditional Antibiotics.

The emergence of drug-resistant strains of pathogens becomes a major obstacle to treating human diseases. Antibiotics and antivirals are in the application for a long time but now these drugs are not much effective anymore against disease-causing drugresistant microbes and gradually it is becoming a serious complication worldwide. The development of new antibiotics cannot be a stable solution to treat drug-resistant strains due to their evolving nature and escaping antibiotics. At this stage, antimicrobial peptides (AMPs) may provide us with novel therapeutic leads against drug-resistant pathogens. Structurally, antimicrobial peptides are mostly α-helical peptide molecules with amphiphilic properties that carry the positive charge (cationic) and belong to host defense peptides. These positively charged AMPs can interact with negatively charged bacterial cell membranes and may cause the alteration in electrochemical potential on bacterial cell membranes and consequently lead to the death of microbial cells. In the present study, we will elaborate on the implication of AMPs in the treatment of various diseases along with their specific structural and functional properties. This review will provide information which assists in the development of new synthetic peptide analogues to natural AMPs. These analogues will eliminate the limitations of natural AMPs like toxicity and severe hemolytic activities.

Possibility of short synthetic peptides with activities of suppressing amyloid β aggregation and resolving its aggregated form as therapeutic drugs for Alzheimer's disease

Lecanemab is a new anti-amyloid antibody being developed as a treatment for Alzheimer's disease. It is expected to delay the progression of the disease by reducing the accumulation of amyloid beta (Aβ) in the brain. However, no drug has been developed that can completely eliminate Aβ and improve symptoms. A representative Catalytide, JAL-TA9 (YKGSGFRMI), cleaves Aβ42 and improves symptoms in an Alzheimer's disease mouse model, suggesting that JAL-TA9 is a promising candidate for treating Alzheimer's disease by effectively eliminating Aβ. The catalytic center of JAL-TA9 is GSGFR. To identify better Catalytides for Alzheimer's treatment, we analyzed the structure-activity relationship of 21 point-mutated GSGFR derivatives. In this process, we discovered two peptides, GSGFK and GSGNR, that not only inhibit Aβ25-35 aggregation but also dissolve aggregated Aβ25-35. Intracerebroventricular administration of GSGFK protected mice against Aβ25-35-induced short-term memory deficits and promoted microglial phagocytic activity. Like Lecanemab, GSGFK targets Aβ, but it has advantages such as safety, administration method, and cost. In this talk, we will discuss the potential of GSGFK as a therapeutic candidate for Alzheimer's disease.

Total Syntheses of Cyclomarin and Metamarin Natural Products.

The first total synthesis of the heptapeptide Cyclomarin A (CymA) was achieved via new routes to chiral amino acid building blocks (highlighted) and solid-phase peptide synthesis. A structurally misassigned epimer of CymA (CymA'), Cyclomarin C, and Metamarin were also synthesized. Affirmation of the syntheses was corroborated by observations that the synthetic molecules have antimicrobial activities mirroring those of the natural products. Interestingly, CymA' is more potent than CymA.

PRR adjuvants restrain high stability peptides presentation on APCs.

Adjuvants can affect APCs function and boost adaptive immune responses post-vaccination. However, whether they modulate the specificity of immune responses, particularly immunodominant epitope responses, and the mechanisms of regulating antigen processing and presentation remain poorly defined. Here, using overlapping synthetic peptides, we screened the dominant epitopes of Th1 responses in mice post-vaccination with different adjuvants and found that the adjuvants altered the antigen-specific CD4+ T-cell immunodominant epitope hierarchy. MHC-II immunopeptidomes demonstrated that the peptide repertoires presented by APCs were significantly altered by the adjuvants. Unexpectedly, no novel peptide presentation was detected after adjuvant treatment, whereas peptides with high binding stability for MHC-II presented in the control group were missing after adjuvant stimulation, particularly in the MPLA- and CpG-stimulated groups. The low-stability peptide present in the adjuvant groups effectively elicited robust T-cell responses and formed immune memory. Collectively, our results suggest that adjuvants (MPLA and CpG) inhibit high-stability peptide presentation instead of revealing cryptic epitopes, which may alter the specificity of CD4+ T-cell-dominant epitope responses. The capacity of adjuvants to modify peptide-MHC (pMHC) stability and antigen-specific T-cell immunodominant epitope responses has fundamental implications for the selection of suitable adjuvants in the vaccine design process and epitope vaccine development.

PRR adjuvants restrain high stability peptides presentation on APCs

Adjuvants can affect APCs function and boost adaptive immune responses post-vaccination. However, whether they modulate the specificity of immune responses, particularly immunodominant epitope responses, and the mechanisms of regulating antigen processing and presentation remain poorly defined. Here, using overlapping synthetic peptides, we screened the dominant epitopes of Th1 responses in mice post-vaccination with different adjuvants and found that the adjuvants altered the antigen-specific CD4+ T-cell immunodominant epitope hierarchy. MHC-II immunopeptidomes demonstrated that the peptide repertoires presented by APCs were significantly altered by the adjuvants. Unexpectedly, no novel peptide presentation was detected after adjuvant treatment, whereas peptides with high binding stability for MHC-II presented in the control group were missing after adjuvant stimulation, particularly in the MPLA- and CpG-stimulated groups. The low-stability peptide present in the adjuvant groups effectively elicited robust T-cell responses and formed immune memory. Collectively, our results suggest that adjuvants (MPLA and CpG) inhibit high-stability peptide presentation instead of revealing cryptic epitopes, which may alter the specificity of CD4+ T-cell-dominant epitope responses. The capacity of adjuvants to modify peptide–MHC (pMHC) stability and antigen-specific T-cell immunodominant epitope responses has fundamental implications for the selection of suitable adjuvants in the vaccine design process and epitope vaccine development.

Arabidopsis RALF4 Rapidly Halts Pollen Tube Growth by Increasing ROS and Decreasing Calcium Cytoplasmic Tip Levels

In recent years, the rapid alkalinization factor (RALF) family of cysteine-rich peptides has been reported to be crucial for several plant signaling mechanisms, including cell growth, plant immunity and fertilization. RALF4 and RALF19 (RALF4/19) pollen peptides redundantly regulate the pollen tube integrity and growth through binding to their receptors ANXUR1/2 (ANX1/2) and Buddha’s Paper Seal 1 and 2 (BUPS1/2), members of the Catharanthus roseus RLK1-like (CrRLK1L) family, and, thus, are essential for plant fertilization. However, the signaling mechanisms at the cellular level that follow these binding events remain unclear. In this study, we show that the addition of synthetic peptide RALF4 rapidly halts pollen tube growth along with the excessive deposition of plasma membrane and cell wall material at the tip. The ratiometric imaging of genetically encoded ROS and Ca2+ sensors-expressing pollen tubes shows that RALF4 treatment modulates the cytoplasmic levels of reactive oxygen species (ROS) and calcium (Ca2+) in opposite ways at the tip. Thus, we propose that pollen RALF4/19 peptides bind ANX1/2 and BUPS1/2 to regulate ROS and calcium homeostasis to ensure proper cell wall integrity and control of pollen tube growth.

Protection of mice against cecal ligation and puncture-induced polymicrobial sepsis by a Fasciola hepatica helminth defence molecule.

Sepsis results from a dysregulated host immune response to infection and is responsible for ~11 million deaths each year. In the laboratory, many aspects of sepsis can be replicated using a cecal ligation and puncture (CLP) model, which is considered the most clinically relevant rodent model of sepsis. In the present study, histological and biomarker multiplex analyses revealed that the CLP model initiated a large-scale inflammatory response in mice by 24 h, with evidence of acute organ damage by 48-72 h. While many typical pro-inflammatory cytokine/chemokines were systemically elevated, a specific array including IL-10, eotaxin, MIP-1α, MIP-1β, MCP-1 and RANTES noticeably increased just prior to animals reaching the humane endpoint. Treatment of mice with 10 μg of a synthetic 68-amino acid peptide derived from an immunomodulatory molecule secreted by a parasitic worm of humans and livestock, Fasciola hepatica, termed Fasciola hepatica helminth defence molecule (FhHDM), potently suppressed the systemic inflammatory profile, protected mice against acute kidney injury, and improved survival between 48 and 72 h post-procedure. These results suggest that the anti-inflammatory parasite-derived FhHDM peptide has potential as a bio-therapeutic treatment for sepsis.

A classical peptide coupling approach for the total synthesis of simnotrelvir

The total synthesis of an oral small-molecule antiviral agent; a structure based developmental drug simnotrelvir has been accomplished. The synthesis involves readily accessible commercial amino acids L-tert-leucine, 4-hydroxy-l-proline and l-glutamic acid that are easily converted to the key intermediates and are coupled together following classical peptide coupling technique using HATU and NMM. One of the crucial step in the synthesis involved a one pot Boc-deprotection and trifluoroacetylation of tert-leucine amino acid moiety mediated by ZnCl2.

Synthetic Antimicrobial Peptides. V. Histidine-containing Antifungal Peptides with a “Linear” Type of Amphipathicity

A number of histidine-containing synthetic antifungal peptides with a “linear” type of amphipathicity (SAMP LTA) (F2Hx, H10F2, H10, where x = 7, 10, 13 and 16) have been synthesized and studied. Biological screening of such histidine-containing peptides for their antifungal and hemolytic activity was carried out. It has been shown that the presented histidine-containing SAMP LTAs are capable of effectively inhibiting the growth of opportunistic fungi Candida albicans and have low hemolytic activity in most cases not exceeding 10% even at their relatively high concentration of 400 μM in a medium containing erythrocytes. The antifungal activity of the studied peptides increases with increasing histidine residues in their composition, reaching the maximum value for the histidine-containing peptide F2H16 (MIC50 = 1.0 µM). It has been shown that as the chain length of peptides increases, their hemolytic toxicity also increases. In terms of therapeutic significance, the optimal peptides in the presented series of peptides were F2H10 and F2H13, which have higher selectivity than the short or longer peptides F2H7 or F2H16. The therapeutic index (TI) for these peptides was 233, 247, 79 and 60, respectively. It has been shown that histidine-containing derivatives of peptides with phenylalanine residues at the N-terminus of the peptide (F2H10) are less effective compared to similar peptides (H10F2) containing phenylalanine residues at the C-terminus. Among all the studied peptides, the most active was the H10 peptide (MIC50 = 0.7 µM), which does not contain phenylalanine residues, which in its antifungal activity is not only more effective than all other histidine-containing peptides, including the F2H16 peptide with 16 histidine residues, but also 4-5 times more effective than the antifungal peptide P113 (MIC50 = 3.4 µM), a short active fragment of natural histatin 5, well known in the literature. Due to its relatively low hemolytic and high antifungal activity, the presented histidine-containing SAMP LTAs have relatively high TI values, more than 60. Among all the studied peptides, peptides H10 and P113 have minimal, almost zero, hemolytic activity. However, due to its higher antifungal activity, the selectivity of peptide H10 (TI 1400) exceeds that of peptide P113 (TI 340) by more than 4 times. Thus, peptide H10, due to its high antifungal activity, low hemolytic toxicity and, accordingly, high therapeutic significance, can be used as a promising antifungal peptide drug.

Omiganan-Based Synthetic Antimicrobial Peptides for the Healthcare of Infectious Endophthalmitis.

Bacterial endophthalmitis is a severe infection of the aqueous or vitreous humor of the eye that can lead to permanent vision loss. Due to the rapid emergence of antibiotic resistance and dose-limiting toxicities, the standard treatment of bacterial endophthalmitis via the intravitreal injection of broad-spectrum antibiotics remains inadequate. Membrane active cationic antimicrobial peptides (AMPs) have emerged as a promising class of effective and broad-spectrum antimicrobial agents with potential to overcome antibiotic resistance. In this work, we investigate, for the first time, the use of omiganan (IK-12), a 12-amino acid indolicidin derivative for the treatment of bacterial endophthalmitis. Additionally, IK-12 was used as a template to perform amino acid rearrangements, without altering the length or type of amino acids, to yield a series of new derivative AMPs with varying extents of secondary structure formation under membrane mimicking conditions. IK-12 and its derivatives demonstrated strong and broad-spectrum antibacterial activities against a panel of clinically isolated Gram-positive and Gram-negative bacteria, including methicillin-resistant Staphylococcus aureus commonly implicated in bacterial endophthalmitis. Interestingly, two of the new IK-12 derivatives, IP-12 and WP-12, showed lower geometric mean minimum inhibitory concentration and higher 50% hemolysis concentration values, which effectively translated into 2- to 3.4-fold higher bacterial selectivity than the parent IK-12. Furthermore, the intravitreal injection of IK-12, IP-12, and WP-12 in a rabbit model of MRSA-induced endophthalmitis led to considerably improved clinical presentation and reduced recruitment of inflammatory cells. In all, these results demonstrate the potential of IK-12 and its derivatives, IP-12 and WP-12, as promising candidates for the treatment of bacterial endophthalmitis.

Selective Activation of Peptide‐Thioester Precursors for Templated Native Chemical Ligations

AbstractChemical protein synthesis enables access to proteins that would otherwise be difficult or impossible to obtain with traditional means such as recombinant expression. Chemoselective ligations provide the ability to join peptide segments prepared by solid‐phase peptide synthesis. While native chemical ligation (NCL) is widely used, it is limited by the need for C‐terminal thioesters with suitable reaction kinetics, properly placed native Cys or thiolated derivatives, and peptide segment solubility at low mM concentrations. Moreover, repetitive purifications to isolate ligated products are often yield‐sapping, hampering efficiency and progress. In this work, we demonstrate the use of Controlled Activation of Peptides for Templated NCL (CAPTN). This traceless multi‐segment templated NCL approach permits the one‐pot synthesis of proteins by harnessing selective thioester activation and orthogonal conjugation chemistries to favor formation of the full‐length ligated product while minimizing side reactions. Importantly, CAPTN provides kinetic enhancements allowing ligations at sterically hindered junctions and low peptide concentrations. Additionally, this one‐pot approach removes the need for intermediate purification. We report the synthesis of two E. coli ribosomal subunits S16 and S17 enabled by the chemical tools described herein. We anticipate that CAPTN will expedite the synthesis of valuable proteins and expand on templated approaches for chemical protein synthesis.

Stereorandomized Oncocins with Preserved Ribosome Binding and Antibacterial Activity.

We recently showed that solid-phase peptide synthesis using racemic amino acids yields stereorandomized peptides comprising all possible diastereomers as homogeneous, single-mass products that can be purified by HPLC and that stereorandomization modulates activity, toxicity, and stability of membrane-disruptive cyclic and linear antimicrobial peptides (AMPs) and dendrimers. Here, we tested if stereorandomization might be compatible with target binding peptides with the example of the proline-rich AMP oncocin, which inhibits the bacterial ribosome. Stereorandomization of up to nine C-terminal residues preserved ribosome binding and antibacterial effects including activities against drug-resistant bacteria and protected against serum degradation. Surprisingly, fully stereorandomized oncocin was as active as L-oncocin in dilute growth media stimulating peptide uptake, although it did not bind the ribosome, indicative of an alternative mechanism of action. These experiments show that stereorandomization can be compatible with target binding peptides and can help understand their mechanism of action.

Effect of peptide hydrophilicity on membrane curvature and permeation.

Using a well-developed reaction coordinate in umbrella sampling, we studied the single peptide permeation through a model cancerous cell membrane, varying the hydrophilicity and the charge of the peptides. Two peptides, melittin and pHD108, were studied. The permeation mechanism differs from a barrel-stave-like mechanism to toroidal pore and vesicle formation based on the number and the placement of the hydrophilic amino acids in the peptide. Membrane curvature changes dynamically as the permeation process occurs. In the case of vesicles, the peptide traverses along a smooth, homogenous pathway, whereas a rugged, steep pathway was found when lipid molecules did not line up along the wall of the membrane (barrel-stave-like mechanism). A mechanism similar to a toroidal pore consists of multiple minima. Higher free energy was found for the permeating terminal containing charged amino acid residues. Vesicle formation was found for pHD108 peptide N-terminal with a maximum membrane thinning effect of 54.4% with free energy cost of 8.20 ± 0.10kcal mol-1 and pore radius of 2.33 ± 0.07nm. Insights gained from this study can help to build synthetic peptides for drug delivery.

Validation and quantification of peptide antigens presented on MHCs using SureQuant.

Vaccines and immunotherapies that target peptide-major histocompatibility complexes (peptide-MHCs) have the potential to address multiple unmet medical needs in cancer and infectious disease. Designing vaccines and immunotherapies to target peptide-MHCs requires accurate identification of target peptides in infected or cancerous cells or tissue, and may require absolute or relative quantification to identify abundant targets and measure changes in presentation under different treatment conditions. Internal standard parallel reaction monitoring (also known as 'SureQuant') can be used to validate and/or quantify MHC peptides previously identified by using untargeted methods such as data-dependent acquisition. SureQuant MHC has three main use cases: (i) conclusive confirmation of the identities of putative MHC peptides via comparison with an internal synthetic stable isotope labeled (SIL) peptide standard; (ii) accurate relative quantification by using pre-formed heavy isotope-labeled peptide-MHC complexes (hipMHCs) containing SIL peptides as internal controls for technical variation; and (iii) absolute quantification of each target peptide by using different amounts of hipMHCs loaded with synthetic peptides containing one, two or three SIL amino acids to provide an internal standard curve. Absolute quantification can help determine whether the abundance of a peptide-MHC is sufficient for certain therapeutic modalities. SureQuant MHC therefore provides unique advantages for immunologists seeking to confidently validate antigenic targets and understand the dynamics of the MHC repertoire. After synthetic standards are ordered (3-4 weeks), this protocol can be carried out in 3-4 days and is suitable for individuals with mass spectrometry experience who are comfortable with customizing instrument methods.

The Therapeutic Potential of GLP-1 Receptor Agonists in the Management of Hidradenitis Suppurativa: A Systematic Review of Anti-Inflammatory and Metabolic Effects.

Background: Glucagon-like peptide-1 receptor agonists (GLP1-RAs) are synthetic peptides that mimic the natural activity of GLP-1, widely known for lowering blood glucose levels and promoting weight reduction. These characteristics make them a valuable tool in managing type 2 diabetes and obesity-related conditions. Recent findings indicate that GLP1-RAs may also offer therapeutic benefits in managing hidradenitis suppurativa (HS), a chronic inflammatory skin disorder closely associated with metabolic abnormalities, including obesity, diabetes, and dyslipidemia. This review explores the potential role of GLP1-RAs in managing HS. Methods: A systematic review was conducted by searching electronic databases, including MEDLINE and Google Scholar, without date limitations. Key search terms included "GLP-1" or "GLP-1 agonists" combined with "hidradenitis suppurativa" or "acne inversa". Inclusion criteria were set for studies reporting on the use of GLP1-RAs as a treatment for HS, with articles discussing theoretical applications excluded. Data synthesis included findings from 25 relevant studies. Results: The analysis revealed that GLP1-RAs, specifically liraglutide and semaglutide, led to significant reductions in weight and systemic inflammation in HS patients. Notably, improvements in lesion severity and quality of life were reported. The anti-inflammatory effects of GLP1-RAs were attributed to the suppression of key inflammatory pathways involving TNF-α, IL-17, and NF-κB. Conclusions: GLP1-RAs demonstrate significant potential as an adjunct therapy for HS, addressing both the metabolic and inflammatory aspects of the condition. While early results are promising, further research is necessary to determine their long-term efficacy in managing HS.

An Enzymatic Method to Obtain Enantiopure 3-Pyridyl andSubstituted Phenyl Alanine.

Chiral phenylalanine derivatives are important raw materials and building blocks for the synthesis of peptides and drug molecules. Enantiomerically pure D/L-3-pyridyl- and phenylalanine has shown wide application potential in the synthesis of various drug intermediates. This article focuses on two synthetic routes from different feedstocks. The first approach is an Erlenmeyer-Plöchl route study using N-acetylglycine as starting material, whereas the second is an alkylation route study using diethyl acetamidomalonate as starting material. The key step is the resolution of N-acetamido-alanine esters using different quantities of fairly inexpensive Protamex proteinase to obtain pure enantiomeric D/L-3-pyridyl- and substituted phenylalanine or its derivative, with the ee value and purity of all products exceeding 99%. The different chiral arylalanine derivatives that can be prepared using the above two methods have good versatility.

Impairing protein-protein interactions in an essential tRNA modification complex: An innovative antimicrobial strategy against Pseudomonas aeruginosa.

Protein-protein interactions (PPIs) have been recognized as a promising target for the development of new drugs, as proved by the growing number of PPI modulators reaching clinical trials. In this context, peptides represent a valid alternative to small molecules, owing to their unique ability to mimic the target protein structure and interact with wider surface areas. Among the possible fields of interest, bacterial PPIs represent an attractive target to face the urgent necessity to fight antibiotic resistance. Growing attention has been paid to the YgjD/YeaZ/YjeE complex responsible for the essential t6A37 tRNA modification in bacteria. We previously identified an α-helix on the surface of Pseudomonas aeruginosa YeaZ, crucial for the YeaZ-YeaZ homodimer formation and the conserved YeaZ-YgjD interactions. Herein, we present our studies for impairing the PPIs involved in the formation of the YeaZ dimers through synthetic peptide derivatives of this helical moiety, both in vitro with purified components and on P. aeruginosa cells. Our results proved the possibility of targeting those PPIs which are usually essential for protein functioning and thus are refractory to mutational changes and antibiotic resistance development.