Fold-back structures at the distal end influence DNA slippage at the proximal end during mononucleotide repeat expansions.
AUTOR(ES)
Karthikeyan, G
RESUMO
Polymerase slippage during DNA synthesis by the Klenow fragment of DNA polymerase across A, C, G and T repeats (30 bases) has been studied. Within minutes, duplexes that contain only repeats (30 bp) expand dramatically to several hundred base pairs long. Rate comparisons in a repeat duplex when one strand was expanded as against that when both strands were expanded suggest a model of migrating hairpin loops which in the latter case coalesce into a duplex. Moreover, slippage (at the proximal or 3'-end) is subject to positive and negative effects from the 5'-end (distal) of the same strand. Growing T and G strands generate T.A:T and G-G:C motif fold-back structures at the distal end that hamper slippage at the proximal end. On the other hand, growing tails at the distal end upon annealing with excess complementary template accentuates proximal slippage several-fold.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=148648Documentos Relacionados
- A knob-associated tandem repeat in maize capable of forming fold-back DNA segments: Are chromosome knobs megatransposons?
- Tc4, a Caenorhabditis elegans transposable element with an unusual fold-back structure.
- The nucleotide sequence of the ubiquitous repetitive DNA sequence B1 complementary to the most abundant class of mouse fold-back RNA.
- Large CAG/CTG repeat templates produced by PCR, usefulness for the DIRECT method of cloning genes with CAG/CTG repeat expansions.
- Mononucleotide repeat polymorphism in the APP gene
