Richter D
Proc Natl Acad Sci U S A. 1976 Mar;73(3):707-11. doi: 10.1073/pnas.73.3.707.
Uncharged tRNA is preferentially bound to the peptidyl site of the ribosome in the absence of stringent factor ,but in its presence is directed to the acceptor site. The synthesis of pppGpp and ppGpp is initiated by tRNA bound in the acceptor but not in the peptidyl site. In this reaction, tRNA is not permanently attached to the acceptor site. Uncharged [32P] tRNA but not 3H-labeled stringent factor is released from the ribosome after each round of stringent factor-dependent hydrolysis of ATP. ATP-32PPi-exchange experiments reveal that exchange is independent of the presence of GTP but strongly enhanced by the addition of stringent factor and tRNA. The tRNA release is suppressed when ATP is replaced by beta, gamma-imido adenosine 5'-triphosphate, 5'-AMP, or GTP.
在没有严谨因子的情况下,未负载的tRNA优先结合于核糖体的肽基部位,但在有严谨因子存在时则被导向受体部位。pppGpp和ppGpp的合成由结合在受体部位而非肽基部位的tRNA起始。在该反应中,tRNA并非永久附着于受体部位。每一轮依赖严谨因子的ATP水解后,未负载的[32P]tRNA而非3H标记的严谨因子从核糖体释放。ATP-32PPi交换实验表明,交换不依赖于GTP的存在,但添加严谨因子和tRNA可显著增强。当ATP被β,γ-亚氨基腺苷5'-三磷酸、5'-AMP或GTP取代时,tRNA的释放受到抑制。