CTG repeats show bimodal amplification in E. coli

Partha S. Sarkar, Haw Chin Chang, F. Brian Boudi, Sita Reddy

Research output: Contribution to journalArticlepeer-review

62 Scopus citations


Trinucleotide repeats in human genetic disorders showing anticipation follow two inheritance patterns as a function of length. Inheritance of 35- 50 repeats show incremental changes, while tracts greater than 80 repeats show large saltatory expansions. We describe a bacterial system that recapitulates this striking bimodal pattern of CTG amplification. Incremental expansions predominate in CTG tracts < Okazaki fragment size, while saltatory expansions increase in repeat tracts ≥ Okazaki fragment size. CTG amplification requires loss of SbcC, a protein that modulates cleavage of single-stranded DNA and degradation of duplex DNA from double-strand breaks. These results suggest that noncanonical single strand-containing secondary structures in Okazaki fragments and/or double-strand breaks in repeat tracts are intermediates in CTG amplification.

Original languageEnglish (US)
Pages (from-to)531-540
Number of pages10
Issue number4
StatePublished - Nov 13 1998
Externally publishedYes

ASJC Scopus subject areas

  • General Biochemistry, Genetics and Molecular Biology


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