Crystal structures of distinct parallel and antiparallel DNA G-quadruplexes reveal structural polymorphism in C9orf72 G4C2 repeats.

ABSTRACT: The abnormal expansion of GGGGCC (G4C2) repeats in the noncoding region of the C9orf72 gene is a major genetic cause of two devastating neurodegenerative disorders, amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). These G4C2 repeats are known to form G-quadruplex (G4) structures, which are hypothesized to contribute to disease pathogenesis. Here, we demonstrated that four DNA G4C2 repeats can fold into two structurally distinct G4 conformations: a parallel and an antiparallel topology. The high-resolution crystal structure of the parallel G4 reveals an eight-layered dimeric assembly, formed by two identical monomeric units. Each unit contains four stacked G-tetrads connected by three propeller CC loops and is stabilized through 5'-to-5' π-π interactions and coordinati

SUBMITTER: Geng Y 

PROVIDER: S-EPMC12421379 | biostudies-literature | 2025 Sep

REPOSITORIES: biostudies-literature