标题：Identification of the Synthesis of Guanosine Tetraphosphate (MS I) as Insertion of a Pyrophosphoryl Group into the 3′-Position in Guanosine 5′-Diphosphate
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1973
卷号：70
期号：2
页码：306-309
DOI：10.1073/pnas.70.2.306
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The phosphate transfer system of Haseltine et al., consisting of a ribosomal wash obtained from a stringent strain of Escherichia coli, washed ribosomes, GTP, and ATP, was used to prepare large quantities of guanosine tetra- and pentaphosphates, the magic spot compounds MS I and MS II of Cashel and Gallant. In our hands, the Haseltine et al. system yielded predominantly guanosine tetraphosphate, ppGpp. This system was used exclusively in the described experiments, with ATP labeled with 32P in the {beta}- and {gamma}-positions as donor. The {beta}-label was found to produce a ppG[IMG]/medium/pstar.gif" ALT="Formula ">p and the {gamma}-label a ppGp[IMG]/medium/pstar.gif" ALT="Formula ">. Furthermore, [3H]GDP + [{gamma}-32P]ATP yielded ppGpp in a 3H:32P ratio of 1:1. The results indicate a transfer of the terminal pyrophosphoryl group of ATP as a unit. The position of the transferred pyrophosphoryl was assayed for by preparation of pG[IMG]/medium/pstar.gif" ALT="Formula "> from ppG[IMG]/medium/pstar.gif" ALT="Formula ">p with Zn++-activated inorganic pyrophosphatase from yeast. The pG[IMG]/medium/pstar.gif" ALT="Formula "> was then assayed with 3'-nucleotidase, which liberated practically all the labeled phosphate. This result indicate that the phosphate transfer from ATP to GDP yields guanosine 5'-diphosphate-3'-diphosphate.
关键词：E. coli ; stringent ; relaxed control ; phosphate transfer
