Biological activity can be predicted at a prescreening stage by using a target‐accelerated combinatorial synthesis. The rate of dimerization of vancomycin analogues (see picture, X=CH=CH2, SAc) in the presence of vancomycin's targets Ac‐D‐Ala‐D‐Ala and Ac2‐L‐Lys‐D‐Ala‐D‐Ala correlated well with the observed biological activity. From this study three highly potent antibacterial agents effective against both vancomycin‐susceptible and vancomycin‐resistant bacteria strains were identified.

The Epstein-Barr virus-induced receptor 2 (EBI2) is a constitutively active seven-transmembrane receptor, which was recently shown to orchestrate the positioning of B cells in the follicle. To date, no ligands, endogenously or synthetic, have been identified that modulate EBI2 activity. Here we describe an inverse agonist, GSK682753A, which selectively inhibited the constitutive activity of EBI2 with high potency and efficacy. In cAMP-response element-binding protein-based reporter and guanosine 5-3-O-(thio)-triphosphate (GTP␥S) binding assays, the potency of this compound was 2.6 -53.6 nM, and its inhibitory efficacy was 75%. In addition, we show that EBI2 constitutively activated extracellular signal-regulated kinase (ERK) in a pertussis toxin-insensitive manner. Intriguingly, GSK682753A inhibited ERK phosphorylation, GTP␥S binding, and cAMP-response element-binding protein activation with similar potency. Overexpression of EBI2 profoundly potentiated antibody-stimulated ex vivo proliferation of murine B cells compared with WT cells, whereas this was equivalently reduced for EBI2-deficient B cells. Inhibition of EBI2 constitutive activity suppressed the proliferation in all cases. Importantly, the suppression was of much higher potency (32-fold) in WT or EBI2-overexpressing B cells compared with EBI2-deficient counterparts. Finally, we screened GSK682753A against an EBI2 mutant library to determine putative molecular binding determinants in EBI2. We identified Phe 111 at position III:08/3.32 as being crucial for GSK682753A inverse agonism because Ala substitution resulted in a >500-fold decrease in IC 50 . In conclusion, we present the first ligand targeting EBI2. In turn, this molecule provides a useful tool for further characterization of EBI2 as well as serving as a potent lead compound.The Epstein-Barr virus (EBV) induced receptor 2 (EBI2; also known as GPR183) is an orphan member of the 7TM 2 receptor family A. EBI2 is up-regulated up to 200-fold in B cells following EBV infection (1). In agreement with an expression pattern primarily restricted to immunological cell types (1, 2), it was recently demonstrated that EBI2 orchestrates the positioning of B cells in the follicle (3, 4). Specifically, expression of EBI2 allowed activated B cells to translocate to the outer follicular regions; in contrast, the absence of EBI2 permitted the cells to enter the germinal centers. Thus, EBI2 mediates the correct localization of B cells during humoral immune responses. To date, no endogenous ligand for EBI2 has been identified. Given that this receptor does not have a close homolog, the chemical nature of such a ligand is difficult to infer. Accordingly, EBI2 has been placed in varying 7TM receptor subgroups by different phylogenetic analyses as being a target of peptide (1, 5) or lipid ligands (6). Nevertheless, many aspects of EBI2 signaling have been revealed. Thus, we have previously demonstrated that EBI2 is constitutively active through G␣ i (but not G␣ q or G␣ s ) and serum response element (but not NFAT or NFB...

Vancomycin, the prototypical member of the glycopeptide family of antibiotics, is a clinically used antibiotic employed against a variety of drug-resistant bacterial strains including methicillin-resistant Staphylococcus aureus (MRSA). The recent emergence of vancomycin resistance, viewed as a growing threat to public health, prompted us to initiate a program aimed at restoring the potency of this important antibiotic through chemical manipulation of the vancomycin structure. Herein, we describe the development of synthetic technology based on the design of a novel selenium safety catch linker, application of this technology to a solid-phase semisynthesis of vancomycin, and the solid- and solution-phase synthesis of vancomycin libraries. Biological evaluation of these compound libraries led to the identification of a number of in vitro highly potent antibacterial agents effective against vancomycin-resistant bacteria. In addition to aiding these investigations, the solid-phase chemistry described herein is expected to enhance the power of combinatorial chemistry and facilitate chemical biology and medicinal chemistry studies.