ABSTRACT
We report here the optimization of an HldE kinase inhibitor to low nanomolar potency, which resulted in the identification of the first reported compounds active on selected E. coli strains. One of the most interesting candidates, compound 86, was shown to inhibit specifically bacterial LPS heptosylation on efflux pump deleted E. coli strains. This compound did not interfere with E. coli bacterial growth (MIC > 32 µg/mL) but sensitized this pathogen to hydrophobic antibiotics like macrolides normally inactive on Gram-negative bacteria. In addition, 86 could sensitize E. coli to serum complement killing. These results demonstrate that HldE kinase is a suitable target for drug discovery. They also pave the way toward novel possibilities of treating or preventing bloodstream infections caused by pathogenic Gram negative bacteria by inhibiting specific virulence factors.
Subject(s)
Anti-Bacterial Agents/chemical synthesis , Benzothiazoles/chemical synthesis , Escherichia coli/drug effects , Multienzyme Complexes/antagonists & inhibitors , Nucleotidyltransferases/antagonists & inhibitors , Phosphotransferases (Alcohol Group Acceptor)/antagonists & inhibitors , Triazines/chemical synthesis , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Benzothiazoles/chemistry , Benzothiazoles/pharmacology , Escherichia coli/pathogenicity , Lipopolysaccharides/pharmacology , Microbial Sensitivity Tests , Structure-Activity Relationship , Triazines/chemistry , Triazines/pharmacology , Virulence/drug effectsABSTRACT
In this paper, we present some elements of our optimization program to decouple triclosan's specific FabI effect from its nonspecific cytotoxic component. The implementation of this strategy delivered highly specific, potent, and nonbiocidal new FabI inhibitors. We also disclose some preclinical data of one of their representatives, 83, a novel antibacterial compound active against resistant staphylococci and some clinically relevant Gram negative bacteria that is currently undergoing clinical trials.
Subject(s)
Anti-Infective Agents, Local/pharmacology , Benzamides/pharmacology , Drug Resistance, Multiple, Bacterial/drug effects , Enoyl-(Acyl-Carrier-Protein) Reductase (NADH)/antagonists & inhibitors , Gram-Negative Bacteria/drug effects , Phenyl Ethers/pharmacology , Triclosan/pharmacology , Animals , Anti-Infective Agents, Local/chemical synthesis , Benzamides/chemical synthesis , Cells, Cultured , Dogs , Drug Evaluation, Preclinical , Humans , Microbial Sensitivity Tests , Models, Molecular , Molecular Structure , Phenyl Ethers/chemical synthesis , Rats , Structure-Activity Relationship , Triclosan/chemical synthesisABSTRACT
A structure-activity relationship study from a screening hit and structure-based design strategy has led to the identification of bisarylureas as potent inhibitors of Streptococcus agalactiae Stk1. As this target has been directly linked to bacterial virulence, these inhibitors can be considered as a promising step towards antivirulence drugs.
Subject(s)
Anti-Bacterial Agents/chemistry , Protein Serine-Threonine Kinases/antagonists & inhibitors , Streptococcus agalactiae/drug effects , Urea/analogs & derivatives , Anti-Bacterial Agents/pharmacology , Gram-Positive Bacteria/drug effects , Structure-Activity Relationship , Urea/pharmacology , Urea/therapeutic use , Virulence/drug effectsABSTRACT
Gram-negative bacteria lacking heptoses in their lipopolysaccharide (LPS) display attenuated virulence and increased sensitivity to human serum and to some antibiotics. Thus inhibition of bacterial heptose synthesis represents an attractive target for the development of new antibacterial agents. HldE is a bifunctional enzyme involved in the synthesis of bacterial heptoses. Development of a biochemical assay suitable for high-throughput screening allowed the discovery of inhibitors 1 and 2 of HldE kinase. Study of the structure-activity relationship of this series of inhibitors led to highly potent compounds.
Subject(s)
Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Gram-Negative Bacteria/drug effects , Multienzyme Complexes/antagonists & inhibitors , Nucleotidyltransferases/antagonists & inhibitors , Phosphotransferases (Alcohol Group Acceptor)/antagonists & inhibitors , Amino Acid Sequence , Anti-Bacterial Agents/chemical synthesis , Escherichia coli/drug effects , Escherichia coli/enzymology , Gram-Negative Bacteria/enzymology , Heptoses/metabolism , Humans , Inhibitory Concentration 50 , Kinetics , Molecular Sequence Data , Sequence Alignment , Sequence Homology, Amino Acid , Structure-Activity RelationshipABSTRACT
Lipopolysaccharides constitute the outer leaflet of the outer membrane of Gram-negative bacteria and are therefore essential for cell growth and viability. The heptosyltransferase WaaC is a glycosyltransferase (GT) involved in the synthesis of the inner core region of LPS. It catalyzes the addition of the first L-glycero-D-manno-heptose (heptose) molecule to one 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo) residue of the Kdo2-lipid A molecule. Heptose is an essential component of the LPS core domain; its absence results in a truncated lipopolysaccharide associated with the deep-rough phenotype causing a greater susceptibility to antibiotic and an attenuated virulence for pathogenic Gram-negative bacteria. Thus, WaaC represents a promising target in antibacterial drug design. Here, we report the structure of WaaC from the Escherichia coli pathogenic strain RS218 alone at 1.9 A resolution, and in complex with either ADP or the non-cleavable analog ADP-2-deoxy-2-fluoro-heptose of the sugar donor at 2.4 A resolution. WaaC adopts the GT-B fold in two domains, characteristic of one glycosyltransferase structural superfamily. The comparison of the three different structures shows that WaaC does not undergo a domain rotation, characteristic of the GT-B family, upon substrate binding, but allows the substrate analog and the reaction product to adopt remarkably distinct conformations inside the active site. In addition, both binary complexes offer a close view of the donor subsite and, together with results from site-directed mutagenesis studies, provide evidence for a model of the catalytic mechanism.
