<p>Optimization of a Benzothiazole Indolene Scaffold Targeting Bacterial Cell Wall Assembly</p>

ABSTRACTThe bacterial cell wall is made of peptidoglycan (PG), a polymer that is essential for maintenance of cell shape and survival. During growth, bacteria remodel their PG, releasing fragments that are predominantly re-internalized by the cell, where they are recycled for synthesis of new PG. Although the PG recycling pathway is widely conserved, its components are not essential and its roles in cell wall homeostasis are not well-understood. Here, we identified LdcV, a Vibrio cholerae L,D-carboxypeptidase that cleaves the terminal D-Alanine from recycled murotetrapeptides. In the absence of ldcV, recycled tetrapeptides accumulated in the cytosol, leading to two toxic consequences for the cell wall. First, incorporation of tetrapeptide-containing PG precursors into the cell wall led to reduction in D,D-cross-linkage between stem peptides, diminishing PG integrity. Second, tetrapeptide accumulation led to a decrease in canonical UDP-pentapeptide precursors, reducing PG synthesis. Thus, LdcV and the recycling pathway promote optimal cell wall assembly and composition. Furthermore, Ldc substrate preference for murotetrapeptides containing canonical (D-Alanine) vs. non-canonical (D-Methionine) D-amino acids is conserved, suggesting that accumulation of tetrapeptide recycling intermediates may modulate PG homeostasis in environments enriched in non-canonical-muropeptides via substrate competition.

Download Full-text

Bacterial cell wall composition and the influence of antibiotics by cell-wall and whole-cell NMR

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2015.0024 ◽

2015 ◽

Vol 370 (1679) ◽

pp. 20150024 ◽

Cited By ~ 52

Author(s):

Joseph A. H. Romaniuk ◽

Lynette Cegelski

Keyword(s):

Cell Wall ◽

Solid State ◽

Bacterial Cell ◽

Solid State Nmr ◽

Cell Wall Composition ◽

Bacterial Cell Wall ◽

Whole Cell ◽

Whole Cells ◽

Cell Wall Assembly ◽

Modes Of Action

The ability to characterize bacterial cell-wall composition and structure is crucial to understanding the function of the bacterial cell wall, determining drug modes of action and developing new-generation therapeutics. Solid-state NMR has emerged as a powerful tool to quantify chemical composition and to map cell-wall architecture in bacteria and plants, even in the context of unperturbed intact whole cells. In this review, we discuss solid-state NMR approaches to define peptidoglycan composition and to characterize the modes of action of old and new antibiotics, focusing on examples in Staphylococcus aureus . We provide perspectives regarding the selected NMR strategies as we describe the exciting and still-developing cell-wall and whole-cell NMR toolkit. We also discuss specific discoveries regarding the modes of action of vancomycin analogues, including oritavancin, and briefly address the reconsideration of the killing action of β-lactam antibiotics. In such chemical genetics approaches, there is still much to be learned from perturbations enacted by cell-wall assembly inhibitors, and solid-state NMR approaches are poised to address questions of cell-wall composition and assembly in S. aureus and other organisms.

Download Full-text