# NMR 1H, 13C, and 15N resonance assignments of the oncogenic Q61R variant of human NRAS in the active, GTP-bound conformation

## TL;DR

This study uses NMR spectroscopy to determine the structure and stability of the NRASQ61R-GTP protein, which is linked to melanoma.

## Contribution

The study provides detailed NMR resonance assignments and structural insights into the active conformation of the oncogenic NRASQ61R variant.

## Key findings

- NRASQ61R-GTP is conformationally stable in solution with minimal peak-broadening observed in NMR spectra.
- The protein exhibits canonical secondary structural elements and less flexible switch regions compared to KRAS4b-GTP.
- 31P NMR experiments confirm the G-domain of NRASQ61R-GTP is predominantly in the active conformation.

## Abstract

NRASQ61R is a frequent mutation in melanoma. Hydrolysis of GTP by NRASQ61R is reported to be much slower than other KRAS and NRAS mutants. Recent structural biology efforts for KRAS and NRAS proteins have been limited to X-ray crystallography and therefore lack insight into the structure and dynamics of these proteins in solution. Here we report the 1HN, 15N, and 13C backbone and sidechain resonance assignments of the G-domain of oncogenic NRASQ61R-GTP (MW 19.3 kDa; aa 1–169) using heteronuclear, multidimensional NMR spectroscopy. NRASQ61R-GTP is a conformationally stable protein in solution. The 1H–15N correlation cross-peaks in a 2D 1H–15N HSQC spectrum collected after 48 h at 298 K remained intact and only minimal signs of peak-broadening were noted for select residues. High resolution NMR allowed unambiguous assignments of the 1H–15N correlation cross-peaks for all aa residues, except Y40, in addition to a significantly large number of aliphatic and aromatic sidechain resonances. NRASQ61R-GTP exhibits canonical secondary structural elements in the 5 (five) α-helices, 6 (six) β-strands, and associated loop regions as predicted in TALOS-N and CSI. Order parameter (RCI-S2) values predicted by TALOS-N indicate that the NRASQ61R-GTP switch (SW) regions and overall backbone are less flexible than observed in KRAS4b-GTP. The SW region rigidification was validated in heteronuclear NOE measurements. 31P NMR experiments indicate that the G-domain of NRASQ61R-GTP is in a predominant state 2 (active) conformation.

The online version contains supplementary material available at 10.1007/s12104-025-10236-3.