NMR analysis of G7-18NATE, a nonphosphorylated cyclic peptide inhibitor of the Grb7 adapter protein

Corrine J Porter, Jacqueline Anne Wilce

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14 Citations (Scopus)

Abstract

The G7-18NATE is a non-phosphorylated, cyclic peptide that specifically inhibits the Grb7 adapter protein implicated in several pathways critical to cell proliferation and migration. It has been shown that G7-18NATE is able to compete with natural ligands for the Grb7 SH2 phosphotyrosine binding site, and to attenuate cell migration in a pancreatic cancer cell line. It is thus an important lead in the development of a selective inhibitor of Grb7 and potential novel anti-cancer therapeutics. The current study reports the solution properties of G7-18NATE determined using NMR spectroscopy in both water pH 2-3 and phosphate buffer pH 6.0, 100 mM NaCl. The spectra reveal that G7-18NATE exists in two distinguishable conformational states on the NMR timescale, most likely due to cis-trans proline isomerisation. In addition, the chemical shift data are consistent with a tendency of G7-18NATE to form a turn about the YDN motif, known to be important for binding, and suggest that this turn is stabilized in low salt and low pH conditions. Low NH temperature coefficients of Tyr-5 and Asn-7 amide protons may reflect their involvement in the formation of hydrogen bonds that stabilize such a turn. Overall, however, the peptide does not form a rigid structure, but exists in a highly flexible state in solution. Averaged (3)J(NH-alphaH) coupling constants and a lack of inter-residue NOEs are characteristic of such peptide solution behavior. This suggests that there is scope for increasing the rigidity of the peptide that may enhance its binding affinity and specificity for Grb7. (c) 2007 Wiley Periodicals, Inc. Biopolymers (Pept Sci), 2007.
Original languageEnglish
Pages (from-to)174 - 181
Number of pages8
JournalBiopolymers (Peptide Science)
Volume88
Issue number2
Publication statusPublished - 2007

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