AGG interruptions in (CGG)(n) DNA repeat tracts modulate the structure and thermodynamics of non-B conformations in vitro.

ABSTRACT: The trinucleotide repeat sequence CGG/CCG is known to expand in the human genome. This expansion is the primary pathogenic signature of fragile X syndrome, which is the most common form of inherited mental retardation. It has been proposed that formation of non-B conformations by the repetitive sequence contributes to the expansion mechanism. It is also known that the CGG/CCG repeat sequence of healthy individuals, which is not prone to expansion, contains AGG/CCT interruptions every 8-11 CGG/CCG repeats. Using DNA containing 19 or 39 CGG repeats, we have found that both the position and number of interruptions modulate the non-B conformation adopted by the repeat sequence. Analysis by chemical probes revealed larger loops and the presence of bulges for sequences containing interruptions.

SUBMITTER: Jarem DA 

PROVIDER: S-EPMC3650493 | biostudies-literature | 2010 Aug

REPOSITORIES: biostudies-literature