Palindromy and the Location of Deletion Endpoints in Escherichia Coli
AUTOR(ES)
Weston-Hafer, K.
RESUMO
The contributions of direct and inverted repeats to deletion formation were studied by characterizing Amp(r) revertants of plasmids with a series of insertion mutations at a specific site in the pBR322 ampicillin resistance (amp) gene. The inserts at this site are palindromic, variable in length, and bracketed by 9- or 10-bp direct repeats of amp sequence. There is an additional direct repeat composed of 4 bp within the insert and 4 bp of adjoining amp sequence. DNA sequencing and colony hybridization of Amp(r) revertants showed that they contained either the parental amp sequence, implying deletion endpoints in the flanking 9- or 10-bp repeats, or a specific 1-bp substitution, implying endpoints in the 4-bp repeats. Although generally direct repeats seem to be used as deletion endpoints with a frequency proportional to their lengths, we found that with uninterrupted palindromes longer than 32 bp, the majority of deletions ended in the 4 bp, not the 9- or 10-bp repeats. This preferential use of the shorter direct repeats associated with palindromes is interpreted according to a DNA synthesis-error model in which hairpin structures formed by intrastrand pairing foster the slippage of nascent strands during DNA synthesis.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1203650Documentos Relacionados
- Limits to the role of palindromy in deletion formation.
- Deletion Formation between the Two Salmonella Typhimurium Flagellin Genes Encoded on the Mini F Plasmid: Escherichia Coli Ssb Alleles Enhance Deletion Rates and Change Hot-Spot Preference for Deletion Endpoints
- Intracellular location of the histonelike protein HU in Escherichia coli.
- Deletion of the Escherichia coli crp Gene
- Cloning and location of the dgsA gene of Escherichia coli.