High-frequency spontaneous deletion of DNA sequences flanked by direct DNA repeats which also contain an internal palindrome

Robert (Stephen) Lloyd, Mary Lou Augustine

Research output: Contribution to journalArticle

2 Scopus citations


The DNA sequences associated with a very high-frequency, spontaneous deletion event have been determined to be two 11-base direct repeats which also contain an internal 6-base palindrome. A parental M13 replicative form (RF) DNA harboring DNA fragments of the T4 denV gene contained these direct repeats and could only be maintained at 5% of the total RF DNA within an infected cell. The remaining RF DNA was deleted for all intervening sequences between the direct repeats (2.2-kb), but one copy of the direct repeat was retained after the deletion had occurred. This site-specific deletion was highly reproducible in that if parental-sized M13 RF DNA was gel purified and transformed back into cells, the deletion occurred at precisely the same sequence as before. Electron microscopic analyses of DNA extracted from cells transformed with parental-sized DNA revealed the presence of excised 2.2-kb double-stranded circular DNA molecules. This observation thus rules out a copy choice replication/deletion mechanism to account for this high-frequency deletion event.

Original languageEnglish (US)
Pages (from-to)135-142
Number of pages8
JournalMutation Research - Fundamental and Molecular Mechanisms of Mutagenesis
Issue number2
Publication statusPublished - 1987
Externally publishedYes



  • DNA sequences
  • high-frequency
  • Internal 6-base palindrome
  • Spontaneous deletion

ASJC Scopus subject areas

  • Molecular Biology
  • Health, Toxicology and Mutagenesis

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