Rachita Dash

Int J Mol Sci. 2023 Mar 20;24(6):5893. doi: 10.3390/ijms24065893.

ABSTRACT

Gomesin is a cationic antimicrobial peptide which is isolated from the haemocytes of the Brazilian tarantula Acanthoscurria gomesiana and can be produced chemically by Fmoc solid-phase peptide synthesis. Gomesin exhibits a range of biological activities, as demonstrated by its toxicity against therapeutically relevant pathogens such as Gram-positive or Gram-negative bacteria, fungi, cancer cells, and parasites. In recent years, a cyclic version of gomesin has been used for drug design and development as it is more stable than native gomesin in human serum and can penetrate and enter cancer cells. It can therefore interact with intracellular targets and has the potential to be developed as a drug lead for to treat cancer, infectious diseases, and other human diseases. This review provides a perspective on the discovery, structure-activity relationships, mechanism of action, biological activity, and potential clinical applications of gomesin.

PMID:36982972 | PMC:PMC10053013 | DOI:10.3390/ijms24065893

Nat Commun. 2023 Mar 22;14(1):1594. doi: 10.1038/s41467-023-37310-5.

ABSTRACT

Phenol-soluble modulins (PSMs) and Staphylococcal protein A (SpA) are key virulence determinants for community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA), an important human pathogen that causes a wide range of diseases. Here, using chemical and genetic approaches, we show that inhibition of TarO, the first enzyme in the wall teichoic acid (WTA) biosynthetic pathway, decreases the expression of genes encoding PSMs and SpA in the prototypical CA-MRSA strain USA300 LAC. Mechanistically, these effects are linked to the activation of VraRS two-component system that directly represses the expression of accessory gene regulator (agr) locus and spa. The activation of VraRS was due in part to the loss of the functional integrity of penicillin-binding protein 2 (PBP2) in a PBP2a-dependent manner. TarO inhibition can also activate VraRS in a manner independent of PBP2a. We provide multiple lines of evidence that accumulation of lipid-linked peptidoglycan precursors is a trigger for the activation of VraRS. In sum, our results reveal that WTA biosynthesis plays an important role in the regulation of virulence gene expression in CA-MRSA, underlining TarO as an attractive target for anti-virulence therapy. Our data also suggest that acquisition of PBP2a-encoding mecA gene can impart an additional regulatory layer for the modulation of key signaling pathways in S. aureus.

PMID:36949052 | PMC:PMC10032271 | DOI:10.1038/s41467-023-37310-5

Nat Med. 2023 Mar 13. doi: 10.1038/s41591-023-02234-6. Online ahead of print.

ABSTRACT

Increasing evidence suggests that the gut microbiome may modulate the efficacy of cancer immunotherapy. In a B cell lymphoma patient cohort from five centers in Germany and the United States (Germany, n = 66; United States, n = 106; total, n = 172), we demonstrate that wide-spectrum antibiotics treatment ('high-risk antibiotics') prior to CD19-targeted chimeric antigen receptor (CAR)-T cell therapy is associated with adverse outcomes, but this effect is likely to be confounded by an increased pretreatment tumor burden and systemic inflammation in patients pretreated with high-risk antibiotics. To resolve this confounding effect and gain insights into antibiotics-masked microbiome signals impacting CAR-T efficacy, we focused on the high-risk antibiotics non-exposed patient population. Indeed, in these patients, significant correlations were noted between pre-CAR-T infusion Bifidobacterium longum and microbiome-encoded peptidoglycan biosynthesis, and CAR-T treatment-associated 6-month survival or lymphoma progression. Furthermore, predictive pre-CAR-T treatment microbiome-based machine learning algorithms trained on the high-risk antibiotics non-exposed German cohort and validated by the respective US cohort robustly segregated long-term responders from non-responders. Bacteroides, Ruminococcus, Eubacterium and Akkermansia were most important in determining CAR-T responsiveness, with Akkermansia also being associated with pre-infusion peripheral T cell levels in these patients. Collectively, we identify conserved microbiome features across clinical and geographical variations, which may enable cross-cohort microbiome-based predictions of outcomes in CAR-T cell immunotherapy.

PMID:36914893 | DOI:10.1038/s41591-023-02234-6

Transgenic Res. 2023 Apr;32(1-2):121-133. doi: 10.1007/s11248-023-00341-1. Epub 2023 Mar 17.

ABSTRACT

Multiple sclerosis (MS) is a debilitating disease that requires prolonged treatment with often severe side effects. One experimental MS therapeutic currently under development is a single amino acid mutant of a plant peptide termed kalata B1, of the cyclotide family. Like all cyclotides, the therapeutic candidate [T20K]kB1 is highly stable as it contains a cyclic backbone that is cross-linked by three disulfide bonds in a knot-like structure. This stability is much sought after for peptide drugs, which despite exquisite selectivity for their targets, are prone to rapid degradation in human serum. In preliminary investigations, it was found that [T20K]kB1 retains oral activity in experimental autoimmune encephalomyelitis, a model of MS in mice, thus opening up opportunities for oral dosing of the peptide. Although [T20K]kB1 can be synthetically produced, a recombinant production system provides advantages, specifically for reduced scale-up costs and reductions in chemical waste. In this study, we demonstrate the capacity of the Australian native Nicotiana benthamiana plant to produce a structurally identical [T20K]kB1 to that of the synthetic peptide. By optimizing the co-expressed cyclizing enzyme, precursor peptide arrangements, and transgene regulatory regions, we demonstrate a [T20K]kB1 yield in crude peptide extracts of ~ 0.3 mg/g dry mass) in whole plants and close to 1.0 mg/g dry mass in isolated infiltrated leaves. With large-scale plant production facilities coming on-line across the world, the sustainable and cost-effective production of cyclotide-based therapeutics is now within reach.

PMID:36930229 | PMC:PMC10102037 | DOI:10.1007/s11248-023-00341-1

Protein Pept Lett. 2023 Mar 15. doi: 10.2174/0929866530666230315113624. Online ahead of print.

ABSTRACT

The high global burden of tuberculosis (TB) and the increasing emergence of the drug-resistant (DR) strain of Mycobacterium tuberculosis (Mtb) emphasize the urgent need for novel anti-mycobacterial agents. Antimicrobial peptides (AMPs) are small peptides widely existing in a variety of organisms and usually have amphiphilic cationic structures, which have a selective affinity to the negatively charged bacterial cell wall. Besides direct bactericidal mechanisms, including interacting with the bacterial cell membrane and interfering with the biosynthesis of the cell wall, DNA, or protein, some AMPs are involved in the host's innate immunity. AMPs are promising alternative or complementary agents for the treatment of DR-TB, given their various antibacterial mechanisms and low cytotoxicity. A large number of AMPs, synthetic or natural, from human to bacteriophage sources, have displayed potent anti-mycobacterial activity in vitro and in vivo. In this review, we summarized the features, antimycobacterial activity, and mechanisms of action of the AMPs according to their sources. Although AMPs have not yet met the expectations for clinical application due to their low bioavailabilities, high cost, and difficulties in large-scale production, their potent antimycobacterial activity and action mechanisms, which are different from conventional antibiotics, make them promising antibacterial agents against DR-Mtb in the future.

PMID:36924097 | DOI:10.2174/0929866530666230315113624

Nat Commun. 2023 Mar 17;14(1):1416. doi: 10.1038/s41467-023-36978-z.

ABSTRACT

Naturally occurring peptides with high membrane permeability often have ester bonds on their backbones. However, the impact of amide-to-ester substitutions on the membrane permeability of peptides has not been directly evaluated. Here we report the effect of amide-to-ester substitutions on the membrane permeability and conformational ensemble of cyclic peptides related to membrane permeation. Amide-to-ester substitutions are shown to improve the membrane permeability of dipeptides and a model cyclic hexapeptide. NMR-based conformational analysis and enhanced sampling molecular dynamics simulations suggest that the conformational transition of the cyclic hexapeptide upon membrane permeation is differently influenced by an amide-to-ester substitution and an amide N-methylation. The effect of amide-to-ester substitution on membrane permeability of other cyclic hexapeptides, cyclic octapeptides, and a cyclic nonapeptide is also investigated to examine the scope of the substitution. Appropriate utilization of amide-to-ester substitution based on our results will facilitate the development of membrane-permeable peptides.

PMID:36932083 | PMC:PMC10023679 | DOI:10.1038/s41467-023-36978-z

J Chem Inf Model. 2023 Mar 17. doi: 10.1021/acs.jcim.2c01573. Online ahead of print.

ABSTRACT

Recently, cyclic peptides have been considered breakthrough drugs because they can interact with "undruggable" targets such as intracellular protein-protein interactions. Membrane permeability is an essential indicator of oral bioavailability and intracellular targeting, and the development of membrane-permeable peptides is a bottleneck in cyclic peptide drug discovery. Although many experimental data on membrane permeability of cyclic peptides have been reported, a comprehensive database is not yet available. A comprehensive membrane permeability database is essential for developing computational methods for cyclic peptide drug design. In this study, we constructed CycPeptMPDB, the first web-accessible database of cyclic peptide membrane permeability. We collected information on a total of 7334 cyclic peptides, including the structure and experimentally measured membrane permeability, from 45 published papers and 2 patents from pharmaceutical companies. To unambiguously represent cyclic peptides larger than small molecules, we used the hierarchical editing language for macromolecules notation to generate a uniform sequence representation of peptides. In addition to data storage, CycPeptMPDB provides several supporting functions such as online data visualization, data analysis, and downloading. CycPeptMPDB is expected to be a valuable platform to support membrane permeability research on cyclic peptides. CycPeptMPDB can be freely accessed at http://cycpeptmpdb.com.

PMID:36930969 | DOI:10.1021/acs.jcim.2c01573

Molecules. 2023 Feb 24;28(5):2114. doi: 10.3390/molecules28052114.

ABSTRACT

Sortase A (SrtA) is an enzyme which attaches proteins, including virulence factors, to bacterial cell walls. It is a potential target for developing anti-virulence agents against pathogenic and antimicrobial resistant bacteria. This study aimed to engineer 𝛽-lactoglobulin protein nanoparticles (PNPs) for encapsulating safe and inexpensive natural SrtA inhibitors (SrtAIs; trans-chalcone (TC), curcumin (CUR), quercetin (QC), and berberine (BR)) to improve their poor aqueous dispersibility, to screen for synergy with antimicrobial peptides (AMPs), and to reduce the cost, dose, and toxicity of AMPs. Minimum inhibitory concentration (MIC), checkerboard synergy, and cell viability assays were performed for SrtAI PNPs against Gram-positive (methicillin-sensitive and -resistant S. aureus) and Gram-negative (E. coli, P. aeruginosa) bacteria alone and combined with leading AMPs (pexiganan, indolicidin, and a mastoparan derivative). Each SrtAI PNP inhibited Gram-positive (MIC: 62.5-125 µg/mL) and Gram-negative (MIC: 31.3-500 µg/mL) bacterial growth. TC PNPs with pexiganan demonstrated synergy against each bacteria, while BR PNPs with pexiganan or indolicidin provided synergy towards S. aureus. Each SrtAI PNP inhibited SrtA (IC₅₀: 25.0-81.8 µg/mL), and did not affect HEK-293 cell viability at their MIC or optimal synergistic concentrations with AMPs. Overall, this study provides a safe nanoplatform for enhancing antimicrobial synergy to develop treatments for superbug infections.

PMID:36903360 | PMC:PMC10004702 | DOI:10.3390/molecules28052114

ACS Chem Biol. 2023 Mar 15. doi: 10.1021/acschembio.2c00680. Online ahead of print.

ABSTRACT

A key limitation for the development of peptides as therapeutics is their lack of cell permeability. Recent work has shown that short, arginine-rich macrocyclic peptides containing hydrophobic amino acids are able to penetrate cells and reach the cytosol. Here, we have developed a new strategy for developing cyclic cell penetrating peptides (CPPs) that shifts some of the hydrophobic character to the peptide cyclization linker, allowing us to do a linker screen to find cyclic CPPs with improved cellular uptake. We demonstrate that both hydrophobicity and position of the alkylation points on the linker affect uptake of macrocyclic cell penetrating peptides (CPPs). Our best peptide, 4i, is on par with or better than prototypical CPPs Arg₉ (R9) and CPP12 under assays measuring total cellular uptake and cytosolic delivery. 4i was also able to carry a peptide previously discovered from an in vitro selection, 8.6, and a cytotoxic peptide into the cytosol. A bicyclic variant of 4i showed even better cytosolic entry than 4i, highlighting the plasticity of this class of peptides toward modifications. Since our CPPs are cyclized via their side chains (as opposed to head-to-tail cyclization), they are compatible with powerful technologies for peptide ligand discovery including phage display and mRNA display. Access to diverse libraries with inherent cell permeability will afford the ability to find cell permeable hits to many challenging intracellular targets.

PMID:36920103 | DOI:10.1021/acschembio.2c00680

ACS Med Chem Lett. 2023 Jan 27;14(3):278-284. doi: 10.1021/acsmedchemlett.2c00486. eCollection 2023 Mar 9.

ABSTRACT

The recent shift toward increasingly larger drug modalities has created a significant demand for novel classes of compounds with high membrane permeability that can inhibit intracellular protein-protein interactions (PPIs). While major advances have been made in the design of cell-permeable helices, stapled β-sheets, and cyclic peptides, the development of large acyclic β-hairpins lags far behind. Therefore, we investigated a series of 26 β-hairpins (MW > 1.6 kDa) belonging to a chemical space far beyond the Lipinski "rule of five" (fbRo5) and showed that, in addition to their innate plasticity, the lipophilicity of these peptides (log D _7.4 ≈ 0 ± 0.7) can be tuned to drastically improve the balance between aqueous solubility and passive membrane permeability.

PMID:36923919 | PMC:PMC10009788 | DOI:10.1021/acsmedchemlett.2c00486

Int J Mol Sci. 2023 Feb 26;24(5):4568. doi: 10.3390/ijms24054568.

ABSTRACT

Alterations in the gut microbiota composition and their associated metabolic dysfunction exist in psoriasis. However, the impact of biologics on shaping gut microbiota is not well known. This study aimed to determine the association of gut microorganisms and microbiome-encoded metabolic pathways with the treatment in patients with psoriasis. A total of 48 patients with psoriasis, including 30 cases who received an IL-23 inhibitor (guselkumab) and 18 cases who received an IL-17 inhibitor (secukinumab or ixekizumab) were recruited. Longitudinal profiles of the gut microbiome were conducted by using 16S rRNA gene sequencing. The gut microbial compositions dynamically changed in psoriatic patients during a 24-week treatment. The relative abundance of individual taxa altered differently between patients receiving the IL-23 inhibitor and those receiving the IL-17 inhibitor. Functional prediction of the gut microbiome revealed microbial genes related to metabolism involving the biosynthesis of antibiotics and amino acids were differentially enriched between responders and non-responders receiving IL-17 inhibitors, as the abundance of the taurine and hypotaurine pathway was found to be augmented in responders treated with the IL-23 inhibitor. Our analyses showed a longitudinal shift in the gut microbiota in psoriatic patients after treatment. These taxonomic signatures and functional alterations of the gut microbiome could serve as potential biomarkers for the response to biologics treatment in psoriasis.

PMID:36902001 | PMC:PMC10002560 | DOI:10.3390/ijms24054568

Molecules. 2023 Feb 25;28(5):2156. doi: 10.3390/molecules28052156.

ABSTRACT

Antimicrobial peptides (AMPs) are essential components of innate immunity across all species. AMPs have become the focus of attention in recent years, as scientists are addressing antibiotic resistance, a public health crisis that has reached epidemic proportions. This family of peptides represents a promising alternative to current antibiotics due to their broad-spectrum antimicrobial activity and tendency to avoid resistance development. A subfamily of AMPs interacts with metal ions to potentiate antimicrobial effectiveness, and, as such, they have been termed metalloAMPs. In this work, we review the scientific literature on metalloAMPs that enhance their antimicrobial efficacy when combined with the essential metal ion zinc(II). Beyond the role played by Zn(II) as a cofactor in different systems, it is well-known that this metal ion plays an important role in innate immunity. Here, we classify the different types of synergistic interactions between AMPs and Zn(II) into three distinct classes. By better understanding how each class of metalloAMPs uses Zn(II) to potentiate its activity, researchers can begin to exploit these interactions in the development of new antimicrobial agents and accelerate their use as therapeutics.

PMID:36903402 | PMC:PMC10004757 | DOI:10.3390/molecules28052156

J Chem Inf Model. 2023 Mar 13. doi: 10.1021/acs.jcim.2c01551. Online ahead of print.

ABSTRACT

There are several classes of short peptide molecules, known as antimicrobial peptides (AMPs), which are produced during the immune responses of living organisms against various infections. In recent years, substantial progress has been achieved in applying machine-learning methods to predict the activities of AMPs against bacteria. In most investigated cases, however, the outcome is not bacterium-specific since the specific features of bacteria, such as chemical composition and structure of membranes, are not considered. To overcome this problem, we developed a new computational approach that allowed us to train several supervised machine-learning models using a specific set of data associated with peptides targeting E. coli bacteria. LASSO regression and Support Vector Machine techniques have been utilized to select, among more than 1500 physicochemical descriptors, the most important features that can be used to classify a peptide as antimicrobial or ineffective against E. coli. We then performed the classification of active versus inactive AMPs using the Support Vector classifiers, Logistic Regression, and Random Forest methods. This computational study allows us to make recommendations of how to design more efficient antibacterial drug therapies.

PMID:36912047 | DOI:10.1021/acs.jcim.2c01551