Hecker M, Schroeter A
Z Allg Mikrobiol. 1984;24(1):57-60.
Stringent and relaxed strains of E. coli subjected to isoleucine starvation were examined by follow-wing the incorporation of 3H-thymidine into chromosomal DNA. After valine treatment to trigger an isoleucine deprivation (p)ppGpp is synthesized in the stringent strain only. Remarkable differences in the morphology of the amino acid starved cells of the stringent and relaxed strains can be observed. Upon isoleucine limitation 3H-thymidine incorporation into DNA is reduced in both strains, but this inhibition is remarkably delayed in the relaxed strain. Our result show that the reduction of chromosomal DNA synthesis during amino acid limitation occurs also without ppGpp, but in the presence of ppGpp this process is accelerated.
通过追踪³H-胸腺嘧啶核苷掺入染色体DNA的情况，对经受异亮氨酸饥饿的大肠杆菌严谨型菌株和松弛型菌株进行了检测。在用缬氨酸处理引发异亮氨酸缺乏后，仅在严谨型菌株中合成了（p）ppGpp。可以观察到严谨型菌株和松弛型菌株的氨基酸饥饿细胞在形态上有显著差异。在异亮氨酸受限的情况下，两种菌株中³H-胸腺嘧啶核苷掺入DNA的量均减少，但在松弛型菌株中这种抑制明显延迟。我们的结果表明，在氨基酸限制期间染色体DNA合成的减少在没有ppGpp的情况下也会发生，但在有ppGpp的情况下这个过程会加速。
