Glycoprotein inhibitors and iodophilic polysaccharide storage in group A Streptococcus pyogenes

Inhibitors of glycoprotein synthesis in eucaryotic cells also inhibited iodophilic polysaccharide (IPS) storage in group A streptococcus pyogenes. Addition of bacitracin or amphomycin, known inhibitors of polyisoprenol phosphate metabolism or lipid-linked oligosaccharide synthesis, indicated that a key intermediate must be synthesized before IPS storage could be detected. Based on inhibitor action and energy requirements the intermediate was most likely an undecaprenol pyrophosphoryl maltosaccharide. Biosynthesis of the maltosaccharide had an ATP requirement as shown by arsenate action but IPS synthesis via amylomaltase was energy independent if the lipid-linked saccharides were preformed. Maltosaccharide acceptor site blockade with 2-deoxy-d-glucose immediately inhibited IPS storage, which demonstrated the need of acceptor glucose residues for transglycosylation activity of amylomaltase. Tunicamycin failed to inhibit IPS synthesis although it was added in lethal concentrations.