Reconstitution of Staphylococcus aureus Lipoteichoic Acid Synthase Activity Identifies Congo Red as a Selective Inhibitor

Abstract

<p class="first" id="P1">Lipoteichoic acid (LTA) is an anionic surface pol-ymer that is essential for normal growth of <i>Staphylococcus aureus</i>, making the LTA polymerase, LTA synthase (LtaS), a proposed drug target for combating Staphylococcal infections. LtaS is a polytopic membrane protein with five membrane-spanning helices and an extracellular domain, and it uses phosphatidyl glycerol to assemble a glycerol phosphate chain on a glycosylated diacylglycerol membrane anchor. We report here the first reconstitution of LtaS polymerization activity and show that the azo dye Congo red inhibits this enzyme both <i>in vitro</i> and in cells. Related azo dyes and the previously reported LtaS inhibitor 1771 have weak or no <i>in vitro</i> inhibitory activity. Synthetic lethality with mutant strains known to be non-viable in the absence of LTA confirms selective inhibition by Congo red. As the only validated LtaS inhibitor, Congo red can serve as a probe to understand how inhibiting lipoteichoic acid biosynthesis affects cell physiology and may also guide the discovery of more potent inhibitors for use in treating <i>S. aureus</i> infections. </p><p id="P2"> <div class="figure-container so-text-align-c"> <img alt="" class="figure" src="/document_file/4e2b75e8-a1fa-43fb-8f0f-b7e740f63f19/PubMedCentral/image/nihms940605u1.jpg"/> </div> </p>