FIG 3 .

Model for the triggering of the stringent stress response by mutations identified in the highly resistant (H*R) isolates. A schematic model for the postulated effect of H*R mutations on the relA-controlled stress response of S. aureus is shown. Functional categories of mutations are defined as in Table 2. HD, hydrolase; SYN, synthetase; TGS, a domain named after three enzymes that contain it [threonyl-tRNA synthetase (ThrRS), GTPase, and guanosine-3′,5′-bis(diphosphate) 3′-pyrophosphohydrolase (SpoT)]; ACT, the domain named after three proteins that carry it [aspartate kinase, chorismate mutase, and prephenate dehydrogenase (TyrA)].