Quinate-based ligands for irreversible inactivation of the bacterial virulence factor DHQ1 enzyme-A molecular insight.

Irreversible inhibition of the enzyme type I dehydroquinase (DHQ1), a promising target for anti-virulence drug development, has been explored by enhancing the electrophilicity of specific positions of the ligand towards covalent lysine modification. For ligand design, we made use of the advantages offered by the intrinsic acid-base properties of the amino substituents introduced in the quinate scaffold, namely compounds 6-7 (R configuration at C3), to generate a potential leaving group, as well as the recognition pattern of the enzyme. The reactivity of the C2-C3 bond (Re face) in the scaffold was also explored using compound 8. The results of the present study show that replacement of the C3 hydroxy group of (-)-quinic acid by a hydroxyamino substituent (compound 6) provides a time-dependent irreversible inhibitor, while compound 7, in which the latter functionality was substituted by an amino group, and the introduction of an oxirane ring at C2-C3 bond, compound 8, do not allow covalent modification of the enzyme. These outcomes were supported by resolution of the crystal structures of DHQ1 from Staphylococcus aureus (Sa-DHQ1) and Salmonella typhi (St-DHQ1) chemically modified by 6 at a resolution of 1.65 and 1.90 Å, respectively, and of St-DHQ1 in the complex with 8 (1.55 Å). The combination of these structural studies with extensive molecular dynamics simulation studies allowed us to understand the molecular basis of the type of inhibition observed. This study is a good example of the importance of achieving the correct geometry between the reactive center of the ligand (electrophile) and the enzyme nucleophile (lysine residue) to allow selective covalent modification. The outcomes obtained with the hydroxyamino derivative 6 also open up new possibilities in the design of irreversible inhibitors based on the use of amino substituents.

The drop plate method as an alternative for Azospirillum spp viable cell enumeration within the consensus protocol of the REDCAI network

Abstract Quality evaluation of commercial inoculants is essential to warrant an adequate cropresponse to inoculation within a biosecurity framework. In this sense, this work is aimed at standardizing and validating the drop plate method for the enumeration of Azospirillum viable cellsas an alternative to the spread plate technique, which is currently proposed in the consensusprotocol of the REDCAI network. Between 14 and 25 private and public laboratories partici-pated in three independent trials. We obtained consistent and robust results that allowed toconfirm that both techniques are equivalent, concluding that the drop plate method is an alternative enumeration technique that is adequate to be included in the abovementioned consensusprotocol.

Resumen La evaluación de la calidad de los inoculantes comerciales es fundamental para garantizar una adecuada respuesta de los cultivos a la inoculación dentro de un marco de bioseguridad. En este sentido, el objetivo de este trabajo fue la estandarización y validación de la técnica de la microgota para la cuantificación de Azospirillum como metodología alternativa a la técnica de siembra en superficie, propuesta actualmente en el protocolo consenso de la Red de Calidad de Inoculantes, REDCAI. Entre 14 y 25 laboratorios, tanto privados como públicos, participaron de tres ensayos independientes. A partir de ellos se obtuvieron resultados reproducibles y robustos que permiten confirmar que ambas técnicas son equivalentes y concluir que la técnica de recuento por la microgota es una alternativa adecuada para ser incluida dentro del mencionado protocolo consenso.

The drop plate method as an alternative for Azospirillum spp. viable cell enumeration within the consensus protocol of the REDCAI network.

Quality evaluation of commercial inoculants is essential to warrant an adequate crop response to inoculation within a biosecurity framework. In this sense, this work is aimed at standardizing and validating the drop plate method for the enumeration of Azospirillum viable cells as an alternative to the spread plate technique, which is currently proposed in the consensus protocol of the REDCAI network. Between 14 and 25 private and public laboratories participated in three independent trials. We obtained consistent and robust results that allowed to confirm that both techniques are equivalent, concluding that the drop plate method is an alternative enumeration technique that is adequate to be included in the abovementioned consensus protocol.

A Suite of Activity-Based Probes To Dissect the KLK Activome in Drug-Resistant Prostate Cancer.

Kallikrein-related peptidases (KLKs) are a family of secreted serine proteases, which form a network (the KLK activome) with an important role in proteolysis and signaling. In prostate cancer (PCa), increased KLK activity promotes tumor growth and metastasis through multiple biochemical pathways, and specific quantification and tracking of changes in the KLK activome could contribute to validation of KLKs as potential drug targets. Herein we report a technology platform based on novel activity-based probes (ABPs) and inhibitors enabling simultaneous orthogonal analysis of KLK2, KLK3, and KLK14 activity in hormone-responsive PCa cell lines and tumor homogenates. Importantly, we identifed a significant decoupling of KLK activity and abundance and suggest that KLK proteolysis should be considered as an additional parameter, along with the PSA blood test, for accurate PCa diagnosis and monitoring. Using selective inhibitors and multiplexed fluorescent activity-based protein profiling (ABPP), we dissect the KLK activome in PCa cells and show that increased KLK14 activity leads to a migratory phenotype. Furthermore, using biotinylated ABPs, we show that active KLK molecules are secreted into the bone microenvironment by PCa cells following stimulation by osteoblasts suggesting KLK-mediated signaling mechanisms could contribute to PCa metastasis to bone. Together our findings show that ABPP is a powerful approach to dissect dysregulation of the KLK activome as a promising and previously underappreciated therapeutic target in advanced PCa.

6-Halopyridylmethylidene Penicillin-Based Sulfones Efficiently Inactivate the Natural Resistance of Pseudomonas aeruginosa to ß-Lactam Antibiotics.

Pseudomonas aeruginosa, a major cause of nosocomial infections, is considered a paradigm of antimicrobial resistance, largely due to hyperproduction of chromosomal cephalosporinase AmpC. Here, we explore the ability of 6-pyridylmethylidene penicillin-based sulfones 1-3 to inactivate the AmpC ß-lactamase and thus rescue the activity of the antipseudomonal ceftazidime. These compounds increased the susceptibility to ceftazidime in a collection of clinical isolates and PAO1 mutant strains with different ampC expression levels and also improved the inhibition kinetics relative to avibactam, displaying a slow deacylation rate and involving the formation of an indolizine adduct. Bromide 2 was the inhibitor with the lowest KI (15.6 nM) and the highest inhibitory efficiency (kinact/KI). Computational studies using diverse AmpC enzymes revealed that the aromatic moiety in 1-3 targets a tunnel-like site adjacent to the catalytic serine and induces the folding of the H10 helix, indicating the potential value of this not-always-evident pocket in drug design.

Activity of Imipenem, Meropenem, Cefepime, and Sulbactam in Combination with the ß-Lactamase Inhibitor LN-1-255 against Acinetobacter spp.

Treatment of infections caused by Acinetobacter spp., particularly A. baumannii, is a major clinical problem due to its high rates of antibiotic resistance. New strategies must be developed; therefore, restoration of ß-lactam efficacy through the use of ß-lactamase inhibitors is paramount. Activities of the antibiotics imipenem, meropenem, cefepime, and sulbactam in combination with the penicillin-sulfone inhibitor LN-1-255 were tested by microdilution against 148 isolates of Acinetobacter spp. collected in 14 hospitals in Spain in 2020. Relevantly, the MIC90 (i.e., minimum concentration at which 90% of isolates were inhibited) of antibiotics in combination with LN-1-255 decreased 4- to 8-fold for all of the Acinetobacter isolates. Considering only the carbapenem-resistant A. baumannii isolates, which produce carbapenem-hydrolyzing class D ß-lactamases, the addition of LN-1-255 decreased the resistance rates from 95.1% to 0% for imipenem, from 100% to 9.8% for meropenem, from 70.7% to 7.3% for cefepime, and sulbactam resistance rates from 9.8% to 0% and intermediate susceptibility rates from 53.7% to 2.4%. The inhibitor also decreased the minimum inhibitory concentrations (MICs) when tested against non-carbapenem-resistant Acinetobacter spp. isolates. In conclusion, combining LN-1-255 with imipenem, meropenem, cefepime, and sulbactam to target A. baumannii, and especially carbapenem-resistant isolates, represents an attractive option that should be developed for the treatment of infections caused by this pathogen.

Self-Immolation of a Bacterial Dehydratase Enzyme by its Epoxide Product.

Disabling the bacterial capacity to cause infection is an innovative approach that has attracted significant attention to fight against superbugs. A relevant target for anti-virulence drug discovery is the type I dehydroquinase (DHQ1) enzyme. It was shown that the 2-hydroxyethylammonium derivative 3 has in vitro activity since it causes the covalent modification of the catalytic lysine residue of DHQ1. As this compound does not bear reactive electrophilic centers, how the chemical modification occurs is intriguing. We report here an integrated approach, which involves biochemical studies, X-ray crystallography and computational studies on the reaction path using combined quantum mechanics/molecular mechanics Umbrella Sampling Molecular Dynamics, that evidences that DHQ1 catalyzes its self-immolation by transforming the unreactive 2-hydroxyethylammonium group in 3 into an epoxide that triggers the lysine covalent modification. This finding might open opportunities for the design of lysine-targeted irreversible inhibitors bearing a 2-hydroxyethylammonium moiety as an epoxide proform, which to our knowledge has not been reported previously.

6-Arylmethylidene Penicillin-Based Sulfone Inhibitors for Repurposing Antibiotic Efficiency in Priority Pathogens.

The ability of 6-(aryl)methylidene penicillin-based sulfones 1-7 to repurpose ß-lactam antibiotics activity with bacterial species that carry carbapenem-hydrolyzing class D ß-lactamases (OXA-23, OXA-24/40 and OXA-48), as well as with class A (TEM-1, CTX-M-2) and class C (CMY-2, DHA-1) enzymes, is reported. The combinations imipenem/3 and imipenem/4 restored almost completely the antibiotic efficacy in OXA-23 and OXA-24/40 carbapenemase-producing A. baumannii strains (1 µg mL-1) and also provided good results for OXA-48 carbapenemase-producing K. pneumoniae strains (4 µg mL-1). Compounds 2-6 in combinations with ceftazidime and ampicillin were also efficient in restoring antibiotic efficacy in E. coli strains carrying class C (CMY-2 and DHA-1) and class A (TEM-1 and CTX-M-2) ß-lactamase enzymes, respectively. Kinetic and inhibition studies with the OXA-24/40 enzyme, protein mass spectrometry analysis and docking studies allowed us to gain an insight into the inhibition mechanism and the experimentally observed differences between the ligands.

Therapeutic Efficacy of LN-1-255 in Combination with Imipenem in Severe Infection Caused by Carbapenem-Resistant Acinetobacter baumannii.

The carbapenem-hydrolyzing class D ß-lactamases (CHDLs) are the main mechanism of carbapenem resistance in Acinetobacter baumannii CHDLs are not effectively inactivated by clinically available ß-lactam-type inhibitors. We have previously described the in vitro efficacy of the inhibitor LN-1-255 in combination with carbapenems. The aim of this study was to compare the efficacy of LN-1-255 with that of imipenem in murine pneumonia using A. baumannii strains carrying their most extended carbapenemases, OXA-23 and OXA-24/40. The blaOXA-23 and blaOXA-24/40 genes were cloned into the carbapenem-susceptible A. baumannii ATCC 17978 strain. Clinical isolates Ab1 and JC12/04, producing the enzymes OXA-23 and OXA-24/40, respectively, were used in the study. Pharmacokinetic (PK) parameters were determined. An experimental pneumonia model was used to evaluate the efficacy of the combined imipenem-LN-1-255 therapy. MICs of imipenem decreased between 32- and 128-fold in the presence of LN-1-255. Intramuscular treatment with imipenem-LN-1-255 (30/50 mg/kg) decreased the bacterial burden by (i) 4 and 1.7 log10 CFU/g lung in the infection with the ATCC 17978-OXA-23 and Ab1 strains, respectively, and by (ii) 2.5 and 4.5 log10 CFU/g lung in the infection produced by the ATCC 17978-OXA-24/40 and the JC12/04 strains, respectively. In all assays, combined therapy offered higher protection against pneumonia than that provided by monotherapy. No toxicity was observed in treated mice. Imipenem treatment combined with LN-1-255 treatment significantly reduced the severity of infection by carbapenem-resistant A. baumannii strains carrying CHDLs. Preclinical assays demonstrated the potential of LN-1-255 and imipenem therapy as a new antibacterial treatment.

Chemo- and Regioselective Lysine Modification on Native Proteins.

Site-selective chemical conjugation of synthetic molecules to proteins expands their functional and therapeutic capacity. Current protein modification methods, based on synthetic and biochemical technologies, can achieve site selectivity, but these techniques often require extensive sequence engineering or are restricted to the N- or C-terminus. Here we show the computer-assisted design of sulfonyl acrylate reagents for the modification of a single lysine residue on native protein sequences. This feature of the designed sulfonyl acrylates, together with the innate and subtle reactivity differences conferred by the unique local microenvironment surrounding each lysine, contribute to the observed regioselectivity of the reaction. Moreover, this site selectivity was predicted computationally, where the lysine with the lowest p Ka was the kinetically favored residue at slightly basic pH. Chemoselectivity was also observed as the reagent reacted preferentially at lysine, even in those cases when other nucleophilic residues such as cysteine were present. The reaction is fast and proceeds using a single molar equivalent of the sulfonyl acrylate reagent under biocompatible conditions (37 °C, pH 8.0). This technology was demonstrated by the quantitative and irreversible modification of five different proteins including the clinically used therapeutic antibody Trastuzumab without prior sequence engineering. Importantly, their native secondary structure and functionality is retained after the modification. This regioselective lysine modification method allows for further bioconjugation through aza-Michael addition to the acrylate electrophile that is generated by spontaneous elimination of methanesulfinic acid upon lysine labeling. We showed that a protein-antibody conjugate bearing a site-specifically installed fluorophore at lysine could be used for selective imaging of apoptotic cells and detection of Her2+ cells, respectively. This simple, robust method does not require genetic engineering and may be generally used for accessing diverse, well-defined protein conjugates for basic biology and therapeutic studies.

Activity of the ß-Lactamase Inhibitor LN-1-255 against Carbapenem-Hydrolyzing Class D ß-Lactamases from Acinetobacter baumannii.

The number of infections caused by Gram-negative pathogens carrying carbapenemases is increasing, and the group of carbapenem-hydrolyzing class D ß-lactamases (CHDLs) is especially problematic. Several clinically important CHDLs have been identified in Acinetobacter baumannii, including OXA-23, OXA-24/40, OXA-58, OXA-143, OXA-235, and the chromosomally encoded OXA-51. The selection and dissemination of carbapenem-resistant A. baumannii strains constitutes a serious global threat. Carbapenems have been successfully utilized as last-resort antibiotics for the treatment of multidrug-resistant A. baumannii infections. However, the spread of OXA carbapenemases is compromising the continued use of these antimicrobials. In response to this clinical issue, it is necessary and urgent to design and develop new specific inhibitors with efficacy against these enzymes. The aim of this work was to characterize the inhibitory activity of LN-1-255 (a 6-alkylidene-2-substituted penicillin sulfone) and compare it to that of two established inhibitors (avibactam and tazobactam) against the most relevant enzymes of each group of class D carbapenemases in A. baumannii The ß-lactamase inhibitor LN-1-255 demonstrated excellent microbiological synergy and inhibition kinetics parameters against all tested CHDLs and a significantly higher activity than tazobactam and avibactam. A combination of carbapenems and LN-1-255 was effective against A. baumannii class D carbapenemases. Docking assays confirmed the affinity of LN-1-255 for the active site of these enzymes. LN-1-255 represents a potential new ß-lactamase inhibitor that may have a significant role in eradicating infections caused by A. baumannii isolates carrying CHDLs.

Targeting the Motion of Shikimate Kinase: Development of Competitive Inhibitors that Stabilize an Inactive Open Conformation of the Enzyme.

The large conformational changes observed by Molecular Dynamics simulation studies on the product release in the LID and shikimic acid binding (SB) domains of the shikimate kinase (SK) enzyme have been exploited in the development of reversible competitive inhibitors against SK from Mycobacterium tuberculosis and Helicobacter pylori. This enzyme is a recognized target for antibiotic drug discovery. The reported C5-substituted shikimic acid analogues interact with the dynamic apolar pocket that surrounds the C4 and C5 hydroxyl groups of the natural substrate, cause the opening of the LID and SB domains, and capture the essential arginine far from the ATP binding site as required for catalysis. The 3-nitrobenzyl 3e and 5-benzothiophenyl derivatives 3i proved to be the most potent inhibitors. An ester prodrug of 3i was the most efficient derivative in achieving good in vitro activity against H. pylori, having a MIC value of 4 µg/mL.

Irreversible covalent modification of type I dehydroquinase with a stable Schiff base.

The irreversible inhibition of type I dehydroquinase (DHQ1), the third enzyme of the shikimic acid pathway, is investigated by structural, biochemical and computational studies. Two epoxides, which are mimetics of the natural substrate, were designed as irreversible inhibitors of the DHQ1 enzyme and to study the binding requirements of the linkage to the enzyme. The epoxide with the S configuration caused the covalent modification of the protein whereas no reaction was obtained with its epimer. The first crystal structure of DHQ1 from Salmonella typhi covalently modified by the S epoxide, which is reported at 1.4 Å, revealed that the modified ligand is surprisingly covalently attached to the essential Lys170 by the formation of a stable Schiff base. The experimental and molecular dynamics simulation studies reported here highlight the huge importance of the conformation of the C3 carbon of the ligand for covalent linkage to this type of aldolase I enzyme, revealed the key role played by the essential His143 as a Lewis acid in this process and show the need for a neatly closed active site for catalysis.

Insights into substrate binding and catalysis in bacterial type I dehydroquinase.

Structural, biochemical and computational studies to study substrate binding and the role of the conserved residues of the DHQ1 (type I dehydroquinase) enzyme active site are reported in the present paper. The crystal structure of DHQ1 from Salmonella typhi in complex with (2R)-2-methyl-3-dehydroquinic acid, a substrate analogue, was solved at 1.5 Å. The present study reveals a previously unknown key role for conserved Glu46, Phe145 and Met205 and Gln236, Pro234 and Ala233 residues, with the latter three being located in the flexible substrate-covering loop. Gln236 was shown to be responsible for the folding of this loop and for the dramatic reduction of its flexibility, which triggers active site closure. Glu46 was found to be key in bringing the substrate close to the lysine/histidine catalytic pocket to initiate catalysis. The present study could be useful in the rational design of inhibitors of this challenging and recognized target for the development of novel herbicides and antimicrobial agents.

El plan jefes y jefas de hogar desocupados: sus efectos en la protesta de los movimientos de trabajadores desocupados / Social programs for unemployed workers in Argentina: its efects on the collective action

El proceso de desindustrialización profundizado por el proyecto neoliberal implementado en la Argentina, dio como resultado una sociedad más desigual, en la cual el desempleo y la informalidad crecieron en forma descomunal. En ese marco, surgió un abanico de movimientos sociales referenciados en el derecho al trabajo. Tras la crisis de 2001, fue implementado el plan Jefes y Jefas de Hogar Desocupados, que pretendía ser una política social que abarcase el universo de los desempleados. En la práctica, no fue universal y fue implementado fundamentalmente a partir de los municipios y, en algún sentido, por organizaciones comunitarias, como los movimientos de trabajadores desocupados. El trabajo pretende presentar el alcance del plan Jefes y Jefas de Hogar Desocupados y el impacto de éste sobre estos movimientos sociales. Interesa analizar el modo en que es leído por parte delos diferentes actores y la dinámica que se establece como respuesta a su implementación.(AU)

The process of desindustrialización as a result of the neoliberal project in Argentina produced a more unequal society, with high unemployment rates. In that frame, arose a range of social movements around employment problems. After the 2001 crisis, was implemented programme for unemployed chiefs of family with the aim of being an universal social policy covering the whole universe of enemployed persons. In fact, the programe was not universalbut implemented, he was not universal and it was implemented by political leaders and, insome sense, by communitarian organizations, such us the movements of vacated workers. In that sense, the work tries to analize the impact of this programe on the social dynamic of unemployed movemts; particularly, how interact the different actors.(AU)

El plan jefes y jefas de hogar desocupados: sus efectos en la protesta de los movimientos de trabajadores desocupados / Social programs for unemployed workers in Argentina: its efects on the collective action

El proceso de desindustrialización profundizado por el proyecto neoliberal implementado en la Argentina, dio como resultado una sociedad más desigual, en la cual el desempleo y la informalidad crecieron en forma descomunal. En ese marco, surgió un abanico de movimientos sociales referenciados en el derecho al trabajo. Tras la crisis de 2001, fue implementado el plan Jefes y Jefas de Hogar Desocupados, que pretendía ser una política social que abarcase el universo de los desempleados. En la práctica, no fue universal y fue implementado fundamentalmente a partir de los municipios y, en algún sentido, por organizaciones comunitarias, como los movimientos de trabajadores desocupados. El trabajo pretende presentar el alcance del plan Jefes y Jefas de Hogar Desocupados y el impacto de éste sobre estos movimientos sociales. Interesa analizar el modo en que es leído por parte delos diferentes actores y la dinámica que se establece como respuesta a su implementación.

The process of desindustrialización as a result of the neoliberal project in Argentina produced a more unequal society, with high unemployment rates. In that frame, arose a range of social movements around employment problems. After the 2001 crisis, was implemented programme for unemployed chiefs of family with the aim of being an universal social policy covering the whole universe of enemployed persons. In fact, the programe was not universalbut implemented, he was not universal and it was implemented by political leaders and, insome sense, by communitarian organizations, such us the movements of vacated workers. In that sense, the work tries to analize the impact of this programe on the social dynamic of unemployed movemts; particularly, how interact the different actors.

Revisitando Germani: a interpretação da modernidade e a teoria da ação / Revisiting Germani: an interpretation of modernity and the theory of action

The work of Italian-German sociologist Gino Germani has traditionally been classified as functionalist. However, recent studies have tended to change this perspective, emphasizing other important influences in his work. Against the backdrop of his broader theory, the objective of this article is to analyze, on the one hand, his perception, in the Latin American transition to modernity, of freedom as the essential issue in politics and daily life, and on the other, how this translates into a theory of action that remains overlooked, although only recently have equivalents been found in Sociology, with his theory being more advanced in certain aspects than contemporary proposals in this direction.