Synthesis of linear plasmid multimers in Escherichia coli K-12.
AUTOR(ES)
Cohen, A
RESUMO
Linear plasmid multimers were identified in extracts of recB21 recC22 strains containing derivatives of the ColE1-type plasmids pACYC184 and pBR322. A mutation in sbcB increases the proportion of plasmid DNA as linear multimers. A model to explain this is based on proposed roles of RecBC enzyme and SbcB enzyme (DNA exonuclease I) in preventing two types of rolling-circle DNA synthesis. Support for this hypothesis was obtained by derepressing synthesis of an inhibitor of RecBC enzyme and observing a difference in control of linear multimer synthesis and monomer circle replication. Reinitiation of rolling-circle DNA synthesis was proposed to occur by recA+-dependent and recA+-independent recombination events involving linear multimers. The presence of linear plasmid multimers in recB and recC mutants sheds new light on plasmid recombination frequencies in various mutant strains.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=212879Documentos Relacionados
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