Marcos Pires

Nature, Published online: 29 April 2020; doi:10.1038/s41586-020-2236-6

Using high-resolution atomic force microscopy of live cells, the authors present an updated view of the cell walls of both Staphylococcus aureus and Bacillus subtilis.

A critical step in peptidoglycan (PG) recycling is the transformation of PG tetrapeptides into tripeptides. Hernández et al. demonstrate that Vibrio cholerae accumulates tetrapeptide PG precursors to downregulate PG synthesis in the stationary phase. Tetrapeptide accumulation relies on the substrate preference of l,d-carboxypeptidases for d-ala versus NCDAA-modified substrates.

Viomycin, an antibiotic that has been used to fight tuberculosis infections, is believed to block the translocation step of protein synthesis by inhibiting ribosomal subunit dissociation and trapping the ribosome in an intermediate state of intersubunit rotation. The mechanism by which viomycin stabilizes this state remains unexplained. To address this,...

Reduction of systemic inflammation without immune system inhibition: A photoswitchable ligand for regulation of immune activation through optical control of the heterodimerization of toll‐like receptors 1 and 2 (TLR1/2) has been developed, offering the potential to regulate immune activation and inflammation.

Abstract

The activation of toll‐like receptors (TLRs) plays important roles in the immune response. The ability to control the activities of TLRs could be usable as a switch for immune response. Here we have rationally designed and synthesized a photoswitchable Pam₃CSK₄ derivative—P10—to control the activation of TLR1/2. The ground‐state trans‐P10 was able to stimulate and activate antigen‐presenting cells (APCs) by promoting TLR1/2 heterodimerization. However, cis‐P10, derived from UV irradiation of trans‐P10, reduced the activities of APCs by impeding the TLR1/2 heterodimerization. In the absence of UV radiation, the cis‐P10 slowly returned to its ground trans state, restoring the activities of the APCs stimulation. Our results indicated that optical control of TLR1/2 heterodimerization mediated by the photoswitchable P10 offers the potential to regulate immune activation and inflammation.

Taking the lead : The highly dynamic secondary TAR RNA structure of HIV‐1 is used to template cycloaddition reactions leading to the generation of triazole‐containing thiazole peptidomimetics as selective leads. The triazole ligand with flexible methylene units selectively binds to TAR RNA over TAR RNA without a bulge and TAR DNA. The ligand presumably binds in the bulge region of the TAR RNA and inhibits its interaction with the Tat peptide.

Abstract

The highly conserved HIV‐1 transactivation response element (TAR) binds to the trans‐activator protein Tat and facilitates viral replication in its latent state. The inhibition of Tat–TAR interactions by selectively targeting TAR RNA has been used as a strategy to develop potent antiviral agents. Therefore, HIV‐1 TAR RNA represents a paradigmatic system for therapeutic intervention. Herein, we have employed biotin‐tagged TAR RNA to assemble its own ligands from a pool of reactive azide and alkyne building blocks. To identify the binding sites and selectivity of the ligands, the in situ cycloaddition has been further performed using control nucleotide (TAR DNA and TAR RNA without bulge) templates. The hit triazole‐linked thiazole peptidomimetic products have been isolated from the biotin‐tagged target templates using streptavidin beads. The major triazole lead generated by the TAR RNA presumably binds in the bulge region, shows specificity for TAR RNA over TAR DNA, and inhibits Tat–TAR interactions.

Fab‐ulous ! A novel small‐molecule‐controlled chimeric antigen receptor T cell (CAR‐T) therapy was developed based on a chemically programmed antibody fragment (Fab) as an on/off switch. As a proof‐of‐concept, a folate‐programmed Fab switch mediated potent and specific eradication of folate‐receptor‐expressing cancer cells by engaging CAR‐T cells in both in vitro and in vivo models of ovarian cancer.

Abstract

Although macromolecules on cell surfaces are predominantly targeted and drugged with antibodies, they harbor pockets that are only accessible to small molecules and constitutes a rich subset of binding sites with immense potential diagnostic and therapeutic utility. Compared to antibodies, however, small molecules are disadvantaged by a less confined biodistribution, shorter circulatory half‐life, and inability to communicate with the immune system. Presented herein is a method that endows small molecules with the ability to recruit and activate chimeric antigen receptor T cells (CAR‐Ts). It is based on a CAR‐T platform that uses a chemically programmed antibody fragment (cp‐Fab) as on/off switch. In proof‐of‐concept studies, this cp‐Fab/CAR‐T system targeting folate binding proteins on the cell surface mediated potent and specific eradication of folate‐receptor‐expressing cancer cells in vitro and in vivo.

Nature, Published online: 22 April 2020; doi:10.1038/d41586-020-01176-0

Airway inflammation improves in mice dosed with a protein from an intestinal parasite.

Killer instinct : A supramolecular polyvalent antibody mimic (PAM) has been synthesized in situ on the surface of natural killer cells by nucleic acid assembly and hybridization under physiological conditions without genetic manipulation. The PAM‐engineered natural killer cells (green) possess a superb ability to bind to and kill cancer cells (red) and thus constitute a promising technology platform for cancer immunotherapy.

Abstract

An ability to promote therapeutic immune cells to recognize cancer cells is important for the success of cell‐based cancer immunotherapy. We present a synthetic method for functionalizing the surface of natural killer (NK) cells with a supramolecular aptamer‐based polyvalent antibody mimic (PAM). The PAM is synthesized on the cell surface through nucleic acid assembly and hybridization. The data show that PAM has superiority over its monovalent counterpart in powering NKs to bind to cancer cells, and that PAM‐engineered NK cells exhibit the capability of killing cancer cells more effectively. Notably, aptamers can, in principle, be discovered against any cell receptors; moreover, the aptamers can be replaced by any other ligands when developing a PAM. Thus, this work has successfully demonstrated a technology platform for promoting interactions between immune and cancer cells.

Getting in your own way . We report fusion proteins consisting of a HER2 binding domain and antibody‐binding domain. Concomitant treatment with a mixture of fusions increased antibody recruitment and antibody‐dependent cellular cytotoxicity (ADCC) for some mixtures. For a fusion containing a Sac7d IgG‐recruiting domain, IgG recruitment is observed, but not ADCC, likely due to inhibition of CD16 binding.

Abstract

We report fusion proteins designed to bind spatially distinct epitopes on the extracellular portion of HER2, a breast cancer biomarker and established therapeutic target, and recruit IgG (either anti‐His₆ or serum IgG) to the cell surface. When the proteins were incubated with anti‐His₆ antibody and various concentrations of a single HER2‐binding protein His₆ fusion, we observed interference and a decrease in antibody recruitment at HER2‐binding protein concentrations exceeding ∼30 nM. In contrast, concomitant treatment with two or three distinct HER2‐binding protein His₆ fusions, and anti‐His₆, results in increased antibody recruitment, even at relatively high HER2‐binding protein concentration. In some instances, increased antibody recruitment leads to increased antibody‐dependent cellular cytotoxicity (ADCC) activity. While a fusion protein consisting of a HER2‐binding nanobody and Sac7d, a protein evolved to recognize the Fc domain of IgG, binds IgG from serum, antibody recruitment does not lead to ADCC activity. Rationales for these disparities are provided. Collectively, our findings have implications for the design of efficacious targeted immunotherapeutic biologics, and ensembles thereof.

Nature, Published online: 15 April 2020; doi:10.1038/s41586-020-2186-z

The authors report near-atomic resolution structures of the R-type bacteriocin from Pseudomonas aeruginosa in the pre-contraction and post-contraction states, and these structures provide insight into the mechanism of action of molecular syringes.

Nature, Published online: 15 April 2020; doi:10.1038/s41586-020-2199-7

Experiments in mice show that a population of neurons in the vagal ganglia respond to the presence of glucose in the gut and connect to neurons in the brainstem, revealing the circuit that underlies the neural basis for the behavioural preference for sugar.

Nature, Published online: 15 April 2020; doi:10.1038/s41586-020-2193-0

The secondary bile acid 3β-hydroxy-deoxycholic (isodeoxycholic) acid, produced by gut bacteria, promotes the generation of colonic extrathymic regulatory T cells, whose immunosuppressive activities are known to be essential for intestinal health.

ABSTRACT

Staphylococcus aureus is a major concern in human health care, mostly due to the increasing prevalence of antibiotic resistance. Intracellular localization of S. aureus plays a key role in recurrent infections by protecting the pathogens from antibiotics and immune responses. Peptidoglycan hydrolases (PGHs) are highly specific bactericidal enzymes active against both drug-sensitive and -resistant bacteria. However, PGHs able to effectively target intracellular S. aureus are not yet available. To overcome this limitation, we first screened 322 recombineered PGHs for staphylolytic activity under conditions found inside eukaryotic intracellular compartments. The most active constructs were modified by fusion to different cell-penetrating peptides (CPPs), resulting in increased uptake and enhanced intracellular killing (reduction by up to 4.5 log units) of various S. aureus strains (including methicillin-resistant S. aureus [MRSA]) in different tissue culture infection models. The combined application of synergistic PGH-CPP constructs further enhanced their intracellular efficacy. Finally, synergistically active PGH-CPP cocktails reduced the total S. aureus by more than 2.2 log units in a murine abscess model after peripheral injection. Significantly more intracellular bacteria were killed by the PGH-CPPs than by the PGHs alone. Collectively, our findings show that CPP-fused PGHs are effective novel protein therapeutics against both intracellular and drug-resistant S. aureus.

IMPORTANCE The increasing prevalence of antibiotic-resistant bacteria is one of the most urgent problems of our time. Staphylococcus aureus is an important human pathogen that has acquired several mechanisms to evade antibiotic treatment. In addition, S. aureus is able to invade and persist within human cells, hiding from the immune response and antibiotic therapies. For these reasons, novel antibacterial strategies against these pathogens are needed. Here, we developed lytic enzymes which are able to effectively target drug-resistant and intracellular S. aureus. Fusion of these so-called enzybiotics to cell-penetrating peptides enhanced their uptake and intracellular bactericidal activity in cell culture and in an abscess mouse model. Our results suggest that cell-penetrating enzybiotics are a promising new class of therapeutics against staphylococcal infections.

Nature Microbiology, Published online: 13 April 2020; doi:10.1038/s41564-020-0694-0

Using a multi-omics approach to analyse meconium and stool samples from babies during the first few days of life, the authors show that the gut is detectably colonized within 16 h of birth, with Escherichia coli dominating, and that this correlates with proteome and metabolome changes including the fermentation of amino acids.

In this paper, Huus et al. demonstrate that undernourished mice fail to develop IgA interactions with commensal Lactobacillus. In response to nutrient restriction, Lactobacillus adapts its surface structure, evading host glycan binding and reducing mucosal colonization. This microbe-host dynamic has implications for the use of Lactobacillus probiotics in undernourished populations.

A variety of N‐methylated peptides were synthesized in high yield without severe racemization via the generation of acylN‐methylimidazolium cations. Brønsted acids dramatically accelerated the reaction. The developed amidation reaction enabled the synthesis of a bulky peptide in higher yield and shorter reaction time in comparison with conventional amidation reactions. The first total synthesis of pterulamides I–IV was also achieved.

Abstract

The development of a robust amide‐bond formation remains a critical aspect of N‐methylated peptide synthesis. In this study, we synthesized a variety of dipeptides in high yields, without severe racemization, from equivalent amounts of amino acids. Highly reactive N‐methylimidazolium cation species were generated in situ to accelerate the amidation. The key to success was the addition of a strong Brønsted acid. The developed amidation enabled the synthesis of a bulky peptide with a higher yield in a shorter amount of time compared with the results of conventional amidation. In addition, the amidation can be performed by using either a microflow reactor or a conventional flask. The first total synthesis of naturally occurring bulky N‐methylated peptides, pterulamides I–IV, was achieved. Based on experimental results and theoretical calculations, we speculated that a Brønsted acid would accelerate the rate‐limiting generation of acyl imidazolium cations from mixed carbonic anhydrides.

by R. Christopher D. Furniss, Markus Kostrzewa, Despoina A. I. Mavridou, Gerald Larrouy-Maumus

Millions of patients with Parkinson’s disease rely on the drug Levodopa for relief from tremors, slowed movement, and other motor symptoms. But many patients experience side effects such as cardiac arrhythmias, nausea, and gastrointestinal problems. Levodopa’s side effects and benefits vary widely among patients. Those puzzling disparities, it turns out,...

Nature Biotechnology, Published online: 07 April 2020; doi:10.1038/s41587-020-0488-1

Recent patents related to new antimicrobial materials and methods of imparting antimicrobial activity to an article or product.