Inhibition of Oncogenic and Activated Wild-Type ras-p21 Protein-Induced Oocyte Maturation by Peptides from the ras-Binding Domain of the raf-p74 Protein, Identified from Molecular Dynamics Calculations

Abstract

In the preceding paper we found from molecular dynamics calculations that the structure of the ras-binding domain (RBD) of raf changes predominantly in three regions depending upon whether it binds to ras-p21 or to its inhibitor protein, rap-1A. These three regions of the RBD involve residues from the protein-protein interaction interface, e.g., between residues 60 and 72, residues 97-110, and 111-121. Since the rap-1A-RBD complex is inactive, these three regions are implicated in ras-p21-induced activation of raf. We have therefore co-microinjected peptides corresponding to these three regions, 62-76, 97-110, and 111-121, into oocytes with oncogenic p21 and microinjected them into oocytes incubated in in insulin, which activates normal p21. All three peptides, but not a control peptide, strongly inhibit both oncogenic p21- and insulin-induced oocyte maturation. These findings corroborate our conclusions from the theoretical results that these three regions constitute raf effector domains. Since the 97-110 peptide is the strongest inhibitor of oncogenic p21, while the 111-121 peptide is the strongest inhibitor of insulin-induced oocyte maturation, the possibility exists that oncogenic and activated normal p21 proteins interact differently with the RBD of raf.

Development of new anti-cancer peptides from conformational energy analysis of the oncogenic ras-p21 protein and its complexes with target proteins

“…On the other hand, as shown for entries 15 and 16 in Figure 4, the RBD 97-110 peptide blocks oncogenic ras-p21-induced maturation to a much greater extent than it blocks insulin-induced maturation (57). Thus this peptide appears to be selective for inhibiting the oncogenic form of ras-p21.…”

“…We then synthesized peptides corresponding to these three raf sequences and co-injected each of them with oncogenic ras-p21 protein into oocytes and also injected each of them into oocytes subsequently incubated with insulin (57). As shown in Figure 4, all three peptides blocked oocyte maturation induced by oncogenic ras-p21 (entries 13, 15 and 17).…”