In vitro evidence for the recognition of 8-oxoGTP by Ras, a small GTP-binding protein

Sun Hee Yoon, Jin Won Hyun, Jinhee Choi, Eun Young Choi, Hee Joon Kim, Su Jae Lee, Myung Hee Chung

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

Oxygen radicals attack guanine bases in DNA but they also attack cytoplasmic GTP forming 8-oxoGTP. The presence of 8-oxoGTP in cytoplasm is evidenced by the fact that cells contain MutT/MTH1 which hydrolyze 8-oxoGTP into 8-oxoGMP. In this study, the interaction between 8-oxoGTP and Ras, a small GTP-binding protein, was tested in vitro, and the action of 8-oxoGTP was compared to that of GTP. When purified Ras was treated with 8-oxoGTPγS, Ras was activated, as indicated by the enhanced binding of Ras with Raf-1. GTPγS also activated Ras but 8-oxoGTPγS had a much more potent effect. In lysates of human embryo kidney 293 cells, 8-oxoGTPγS activated not only Ras but also the downstream effectors of the Ras-ERK pathway, i.e., Raf-1 and ERK1/2. In contrast to Ras, other small GTP-binding proteins, Rac1 and Cdc42, were inactivated by 8-oxoGTPγS, whereas both of these proteins were activated by GTPγS, indicating that the biological natures of 8-oxoGTP and GTP differ. These results suggest the possibility that 8-oxoGTP is not a simple by-product but a functional molecule transmitting an oxidative signal to small GTP-binding proteins like Ras.

Original languageEnglish
Pages (from-to)342-348
Number of pages7
JournalBiochemical and Biophysical Research Communications
Volume327
Issue number1
DOIs
StatePublished - 4 Feb 2005

Keywords

  • 8-oxoGTP
  • Oxidative stress
  • Ras
  • Small GTP-binding protein

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