B. subtilis LytR-CpsA-Psr Enzymes Transfer Wall Teichoic Acids from Authentic Lipid-Linked Substrates to Mature Peptidoglycan In Vitro

Gram-positive bacteria endow their peptidoglycan with glycopolymers that are crucial for viability and pathogenesis. However, the cellular machinery that executes this function is not well understood. While decades of genetic and phenotypic work have highlighted the LytR-CpsA-Psr (LCP) family of enzymes as cell-wall glycopolymer transferases, their in vitro characterization has been elusive, largely due to a paucity of tools for functional assays. In this report, we synthesized authentic undecaprenyl diphosphate-linked wall teichoic acid (WTA) intermediates and built an assay system capable of monitoring LCP-mediated glycopolymer transfer. We report that all Bacillus subtilis LCP enzymes anchor WTAs to peptidoglycan in vitro. Furthermore, we probed the catalytic requirements and substrate preferences for these LCP enzymes and elaborated in vitro conditions for facile tests of enzyme function. This work sheds light on the molecular features of glycopolymer transfer and aims to aid drug discovery and development programs exploiting this promising antibacterial target.