bms-187745 and staphyloxanthin

Clinically useful antibiotics, β-lactams and vancomycin, are known to inhibit bacterial cell wall peptidoglycan synthesis. Methicillin-resistant Staphylococcus aureus (MRSA) has a unique cell wall structure consisting of peptidoglycan and wall teichoic acid. In recent years, new anti-infectious agents (spirohexaline, tripropeptin C, DMPI, CDFI, cyslabdan, 1835F03, and BPH-652) targeting MRSA cell wall biosynthesis have been discovered using unique screening methods. These agents were found to inhibit important enzymes involved in cell wall biosynthesis such as undecaprenyl pyrophosphate (UPP) synthase, FemA, flippase, or UPP phosphatase. In this review, the discovery, the mechanism of action, and the future of these anti-infectious agents are described.

Topics: Acetylcysteine; Alkyl and Aryl Transferases; Anti-Bacterial Agents; Bacterial Proteins; beta-Lactams; Cell Wall; Diterpenes; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Mycotoxins; Organothiophosphorus Compounds; Peptidoglycan; Spiro Compounds; Teichoic Acids; Vancomycin; Virulence Factors; Xanthophylls

Staphylococcus aureus produces hospital- and community-acquired infections, with methicillin-resistant S. aureus posing a serious public health threat. The golden carotenoid pigment of S. aureus, staphyloxanthin, promotes resistance to reactive oxygen species and host neutrophil-based killing, and early enzymatic steps in staphyloxanthin production resemble those for cholesterol biosynthesis. We determined the crystal structures of S. aureus dehydrosqualene synthase (CrtM) at 1.58 angstrom resolution, finding structural similarity to human squalene synthase (SQS). We screened nine SQS inhibitors and determined the structures of three, bound to CrtM. One, previously tested for cholesterol-lowering activity in humans, blocked staphyloxanthin biosynthesis in vitro (median inhibitory concentration approximately 100 nM), resulting in colorless bacteria with increased susceptibility to killing by human blood and to innate immune clearance in a mouse infection model. This finding represents proof of principle for a virulence factor-based therapy against S. aureus.

Topics: Amino Acid Sequence; Animals; Anti-Bacterial Agents; Bacterial Proteins; Cell Line; Cell Proliferation; Cholesterol; Crystallography, X-Ray; Enzyme Inhibitors; Farnesyl-Diphosphate Farnesyltransferase; Humans; Mice; Molecular Sequence Data; Organothiophosphorus Compounds; Polyisoprenyl Phosphates; Protein Structure, Secondary; Sesquiterpenes; Staphylococcal Infections; Staphylococcus aureus; Virulence; Xanthophylls