We now present the first example in which triplet repeat DNAs adopt the i-motif structure at neutral pH by molecular crowding. Crowding stabilized the i-motif and the pK(a) of N3 of cytosine was raised in such a microenvironment. Molecular crowding is known to accelerate the formation of the multi-stranded i-motif while the triplet repeats adopt the single-strand structure.

The mechanisms of trinucleotide repeat expansions, underlying more than a dozen hereditary neurological disorders, are yet to be understood. Here we looked at the replication of (CGG)(n) x (CCG)(n) and (CAG)(n) x (CTG)(n) repeats and their propensity to expand in Saccharomyces cerevisiae. Using electrophoretic analysis of replication intermediates, we found that (CGG)(n) x (CCG)(n) repeats sign...

DNA must constantly be repaired to maintain genome stability. Although it is clear that DNA repair reactions depend on cell type and developmental stage, we know surprisingly little about the mechanisms that underlie this tissue specificity. This is due, in part, to the lack of adequate study systems. This review discusses recent progress toward understanding the mechanism leading to varying ra...

In most trinucleotide repeat (TNR) diseases, the primary factor determining the likelihood of expansions is the length of the TNR. In some diseases, however, stable alleles contain one to three base pair substitutions that interrupt the TNR tract. The unexpected stability of these alleles compared to the frequent expansions of perfect TNRs suggested that interruptions somehow block expansions a...

Environment-dependent genomic features have been defined for different metagenomes, whose genes and their associated processes are related to specific environments. Identification of ORFs and their functional categories are the most common methods for association between functional and environmental features. However, this analysis based on finding ORFs misses noncoding sequences and, therefore...

Myotonic dystrophy type 1 (DM1) is associated with one of the most highly unstable CTG*CAG repeat expansions. The formation of further repeat expansions in transgenic mice carrying expanded CTG*CAG tracts requires the mismatch repair (MMR) proteins MSH2 and MSH3, forming the MutSbeta complex. It has been proposed that binding of MutSbeta to CAG hairpins blocks its ATPase activity compromising h...

1 Caine ED, Shoulson T. Psychiatric syndrome in Huntington's disease. AmJPsychiatry 1983; 140:728-33. 2 Seeman P, Niznik HB, Guan HC, et al. Link between DI and D2 dopamine receptor is reduced in schizophrenia and Huntington's disease brain. Proc Natl Acad Sci USA 1989; 86:10156-60. 3 MacDonald ME, Ambrose CM, Duyao MP, et al. A novel gene containing a trinucleotide repeat that is expanded and ...

Background/aim: Huntington disease (HD) is a progressive adult-onset neurodegenerative disorder presenting an autosomal dominant inheritance. Since there is no information on the prevalence of HD in northwestern Iran, the aim of the present study was to determine the prevalence of HD and the number of CAG trinucleotide repeats in the population of northwestern Iran.Materials and methods: Genomi...