Ishiguro E E, Ramey W D
J Bacteriol. 1976 Sep;127(3):1119-26. doi: 10.1128/jb.127.3.1119-1126.1976.
[3H]Diaminopimelic acid (Dap) was incorporated exclusively into peptidoglycan by Escherichia coli strains auxotrophic for both lysine and Dap. The rate of [3H]Dap incorporation by stringent (rel+) strains was significantly decreased when cells were deprived of required amino acids. The addition of chloramphenicol to amino acid-starved rel+ cultured stimulated both peptidoglycan and ribonucleic acid synthesis. In contrast, a relaxed (relA) derivative incorporated [3H]Dap at comparable rates in the presence or absence of required amino acids. Physiologically significant concentrations of guanosine 5'-diphosphate 3'-diphosphate (ppGpp) inhibited the in vitro synthesis of both carrier lipid-linked intermediate and peptidoglycan catalyzed by a particulate enzyme system. The degree of inhibition was dependent on the concentration of ppGpp in the reaction mixture. Thus, the results of in vivo and in vitro studies indicate that peptidoglycan synthesis is stringently controlled in E. coli.
[3H]二氨基庚二酸（Dap）仅被赖氨酸和Dap营养缺陷型的大肠杆菌菌株掺入肽聚糖中。当细胞缺乏必需氨基酸时，严谨型（rel +）菌株掺入[3H] Dap的速率显著降低。向氨基酸饥饿的rel +培养物中添加氯霉素可刺激肽聚糖和核糖核酸的合成。相比之下，松弛型（relA）衍生物在存在或不存在必需氨基酸的情况下以相当的速率掺入[3H] Dap。生理上显著浓度的鸟苷5'-二磷酸3'-二磷酸（ppGpp）抑制了由颗粒酶系统催化的载体脂质连接中间体和肽聚糖的体外合成。抑制程度取决于反应混合物中ppGpp的浓度。因此，体内和体外研究结果表明，大肠杆菌中的肽聚糖合成受到严格控制。
