ABSTRACT
Specific molecular recognition is routine for biology, but has proved difficult to achieve in synthetic systems. Carbohydrate substrates are especially challenging, because of their diversity and similarity to water, the biological solvent. Here we report a synthetic receptor for glucose, which is biomimetic in both design and capabilities. The core structure is simple and symmetrical, yet provides a cavity which almost perfectly complements the all-equatorial ß-pyranoside substrate. The receptor's affinity for glucose, at Ka ~ 18,000 M-1, compares well with natural receptor systems. Selectivities also reach biological levels. Most other saccharides are bound approximately 100 times more weakly, while non-carbohydrate substrates are ignored. Glucose-binding molecules are required for initiatives in diabetes treatment, such as continuous glucose monitoring and glucose-responsive insulin. The performance and tunability of this system augur well for such applications.
Subject(s)
Biomimetic Materials , Glucose , Receptors, Artificial , Receptors, Cell Surface , Animals , Biomimetic Materials/chemistry , Biomimetic Materials/metabolism , Glucose/chemistry , Glucose/metabolism , Humans , Lectins , Models, Molecular , Receptors, Artificial/chemistry , Receptors, Artificial/metabolism , Receptors, Cell Surface/chemistry , Receptors, Cell Surface/metabolism , Synthetic BiologyABSTRACT
Antibiotic resistance continues to reduce the number of available antibiotics, increasing the need for novel antibacterial drugs. Since the seminal work of Sir Alexander Fleming, antibiotic identification has been based exclusively on the inhibition of bacterial growth in vitro. Recently, inhibitors of bacterial virulence which interfere with bacterial pathogenesis mechanisms have been proposed as an alternative to antibiotics, and a few were discovered using assays targeting specific virulence mechanisms. Here we designed a simple surrogate host model for the measurement of virulence and systematic discovery of anti-virulence molecules, based on the interaction of Tetrahymena pyriformis and Klebsiella pneumoniae cells. We screened a library of small molecules and identified several inhibitors of virulence. In a mouse pneumonia model we confirmed that an anti-virulence molecule displayed antibacterial activity against Klebsiella pneumoniae and Pseudomonas aeruginosa, by reducing dramatically the bacterial load in the lungs. This molecule did not inhibit bacterial growth in vitro but prevented biosynthesis of the Klebsiella capsule and lipopolysaccharides, a key requirement for virulence. Our results demonstrate that anti-virulence molecules represent an alternative to antibiotics and those can be discovered using non-animal host models.
Subject(s)
Anti-Bacterial Agents/pharmacology , Bacteria/drug effects , Disease Models, Animal , Animals , Anti-Bacterial Agents/chemistry , Bacteria/genetics , Bacteria/pathogenicity , Cefotaxime/pharmacology , Ceftizoxime/analogs & derivatives , Cyclophosphamide/pharmacology , Female , Klebsiella Infections/complications , Klebsiella Infections/drug therapy , Klebsiella Infections/microbiology , Klebsiella pneumoniae/drug effects , Klebsiella pneumoniae/genetics , Klebsiella pneumoniae/pathogenicity , Lung/drug effects , Lung/microbiology , Mice , Mice, Inbred BALB C , Molecular Structure , Mutation , Neutropenia/drug therapy , Neutropenia/etiology , Pseudomonas aeruginosa/drug effects , Pseudomonas aeruginosa/genetics , Pseudomonas aeruginosa/pathogenicity , Tetrahymena pyriformis/drug effects , Tetrahymena pyriformis/growth & development , Time Factors , Triazines/chemistry , Triazines/pharmacology , Virulence/drug effects , CefpodoximeABSTRACT
The first inhibitors of fungal protein: mannosyl transferase 1 (PMT1) are described. They are based upon rhodanine-3-acetic acid and several compounds have been identified, for example, 5-[[3-(1-phenylethoxy)-4-(2-phenylethoxy)phenyl]methylene]-4-oxo-2-thioxo-3-thiazolidineacetic acid (5a), which inhibit Candida albicans PMT1 with IC(50)s in the range 0.2-0.5 microM. Members of the series are effective in inducing changes in morphology of C. albicans in vitro that have previously been associated with loss of the transferase activity. These compounds could serve as useful tools for studying the effects of protein O-mannosylation and its relevance in the search for novel antifungal agents.
