Crystal Structure of an i-Motif from the HRAS Oncogene Promoter.

ABSTRACT: An i-motif is a non-canonical DNA structure implicated in gene regulation and linked to cancers. The C-rich strand of the HRAS oncogene, 5'-CGCCCGTGCCCTGCGCCCGCAACCCGA-3' (herein referred to as iHRAS), forms an i-motif in vitro but its exact structure was unknown. HRAS is a member of the RAS proto-oncogene family. About 19 % of US cancer patients carry mutations in RAS genes. We solved the structure of iHRAS at 1.77 Å resolution. The structure reveals that iHRAS folds into a double hairpin. The two double hairpins associate in an antiparallel fashion, forming an i-motif dimer capped by two loops on each end and linked by a connecting region. Six C-C⁺ base pairs form each i-motif core, and the core regions are extended by a G-G base pair and a cytosine stacking. Extensive canonic

SUBMITTER: Li KS 

PROVIDER: S-EPMC10330059 | biostudies-literature | 2023 Jun

REPOSITORIES: biostudies-literature