{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,4]],"date-time":"2026-10-04T18:41:35Z","timestamp":1791139295331,"version":"4.1.0"},"reference-count":44,"publisher":"Oxford University Press (OUP)","issue":"2","license":[{"start":{"date-parts":[[2014,7,31]],"date-time":"2014-07-31T00:00:00Z","timestamp":1406764800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/journals\/pages\/open_access\/funder_policies\/chorus\/standard_publication_model"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2014,10,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n               <jats:p>The expansion of CAG\u00b7CTG repeat tracts is responsible for several neurodegenerative diseases, including Huntington disease and myotonic dystrophy. Understanding the molecular mechanism of CAG\u00b7CTG repeat tract expansion is therefore important if we are to develop medical interventions limiting expansion rates. Escherichia coli provides a simple and tractable model system to understand the fundamental properties of these DNA sequences, with the potential to suggest pathways that might be conserved in humans or to highlight differences in behavior that could signal the existence of human-specific factors affecting repeat array processing. We have addressed the genetics of CAG\u00b7CTG repeat expansion in E. coli and shown that these repeat arrays expand via an orientation-independent mechanism that contrasts with the orientation dependence of CAG\u00b7CTG repeat tract contraction. The helicase Rep contributes to the orientation dependence of repeat tract contraction and limits repeat tract expansion in both orientations. However, RuvAB-dependent fork reversal, which occurs in a rep mutant, is not responsible for the observed increase in expansions. The frequency of repeat tract expansion is controlled by both the 5\u2032\u20133\u2032 exonuclease RecJ and the 3\u2032\u20135\u2032 exonuclease ExoI, observations that suggest the importance of both 3\u2032and 5\u2032 single-strand ends in the pathway of CAG\u00b7CTG repeat tract expansion. We discuss the relevance of our results to two competing models of repeat tract expansion.<\/jats:p>","DOI":"10.1534\/genetics.114.168245","type":"journal-article","created":{"date-parts":[[2014,8,1]],"date-time":"2014-08-01T07:03:03Z","timestamp":1406876583000},"page":"509-517","source":"Crossref","is-referenced-by-count":5,"title":["Expansion of CAG Repeats in <i>Escherichia coli<\/i> Is Controlled by Single-Strand DNA Exonucleases of Both Polarities"],"prefix":"10.1093","volume":"198","author":[{"given":"Adam","family":"Jackson","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ewa A","family":"Okely","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"David R F","family":"Leach","sequence":"additional","affiliation":[{"name":"Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3JR, United Kingdom"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"286","published-online":{"date-parts":[[2014,7,31]]},"reference":[{"key":"2022011301120819000_bib1","doi-asserted-by":"crossref","first-page":"596","DOI":"10.1038\/sj.emboj.7600941","article-title":"RuvAB is essential for replication forks reversal in certain replication mutants.","volume":"25","author":"Baharoglu","year":"2006","journal-title":"EMBO J."},{"key":"2022011301120819000_bib2","doi-asserted-by":"crossref","first-page":"1453","DOI":"10.1126\/science.277.5331.1453","article-title":"The complete genome sequence of Escherichia coli K-12.","volume":"277","author":"Blattner","year":"1997","journal-title":"Science"},{"key":"2022011301120819000_bib3"},{"key":"2022011301120819000_bib4","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1007\/978-1-62703-411-1_1","article-title":"A brief history of triplet repeat diseases.","volume":"1010","author":"Budworth","year":"2013","journal-title":"Methods Mol. 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