Ras regulation by reactive oxygen and nitrogen species.
Ras GTPases cycle between inactive GDP-bound and active GTP-bound states to modulate a diverse array of processes involved in cellular growth control. We have previously shown that both NO/O(2) (via nitrogen dioxide, (*)NO(2)) and superoxide radical anion (O(2)(*)(-)) promote Ras guanine nucleotide dissociation. We now show that hydrogen peroxide in the presence of transition metals (i.e., H(2)O(2)/transition metals) and peroxynitrite also trigger radical-based Ras guanine nucleotide dissociation. The primary redox-active reaction species derived from H(2)O(2)/transition metals and peroxynitrite is O(2)(*)(-) and (*)NO(2), respectively. A small fraction of hydroxyl radical (OH(*)) is also present in both. We also show that both carbonate radical (CO(3)(*)(-)) and (*)NO(2), derived from the mixture of peroxynitrite and bicarbonate, facilitate Ras guanine nucleotide dissociation. We further demonstrate that NO/O(2) and O(2)(*)(-) promote Ras GDP exchange with GTP in the presence of a radical-quenching agent, ascorbate, or NO, and generation of Ras-GTP promotes high-affinity binding of the Ras-binding domain of Raf-1, a downstream effector of Ras. S-Nitrosylated Ras (Ras-SNO) can be formed when NO serves as a radical-quenching agent, and hydroxyl radical but not (*)NO(2) or O(2)(*)(-) can further react with Ras-SNO to modulate Ras activity in vitro. However, given the lack of redox specificity associated with the high redox potential of OH(*), it is unclear whether this reaction occurs under physiological conditions.
Heo
Jongyun
J
Department of Biochemistry and Biophysics, University of North Carolina, 530 Mary Ellen Jones Building, Chapel Hill, North Carolina 27599-7260, USA.
Campbell
Sharon L
SL
D003300:Copper / Q000494:pharmacology; D005296:Ferrous Compounds / Q000494:pharmacology; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D030421:Peroxynitrous Acid / Q000494:pharmacology; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D026361:Reactive Nitrogen Species / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000494:pharmacology*; D020663:ras Guanine Nucleotide Exchange Factors / Q000378:metabolism; D018631:ras Proteins / Q000378:metabolism*
D005296:Ferrous Compounds; D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; D020663:ras Guanine Nucleotide Exchange Factors; D006153:Guanosine Diphosphate; D030421:Peroxynitrous Acid; D003300:Copper; D006160:Guanosine Triphosphate; D006861:Hydrogen Peroxide; D019908:Proto-Oncogene Proteins c-raf; D018631:ras Proteins