These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Partition functions of mini-F affect plasmid DNA topology in Escherichia coli.
    Author: Biek DP, Strings J.
    Journal: J Mol Biol; 1995 Feb 24; 246(3):388-400. PubMed ID: 7877163.
    Abstract:
    Efficient segregation of the low copy number plasmid mini-F is dependent on partition functions encoded by the plasmid sopABC genes. The sop region encodes proteins SopA and SopB and a cis-acting element, sopC, which may function as a centromere analog. The SopC segment contains 12 imperfect 43 bp repeats to which the SopB protein binds. We have found that mutations in the sop genes affect superhelicity of isolated plasmid DNA. Plasmids with mutations in sopB or a deletion of the sopC segment were more highly negatively supercoiled than normal. In contrast, a mutation in the autoregulatory SopA protein resulted in plasmid DNA that was more relaxed. The SopAB proteins provided in trans to a pBR322 plasmid carrying sopC resulted in the relaxation of negative supercoils. We suggest that binding of SopB protein to the cis-acting sopC segment in vivo, alone or in conjunction with other proteins, produced a change in DNA topology in which positive superhelical turns were introduced locally. This higher-order nucleoprotein structure may allow interaction of plasmid mini-F with the partition apparatus.
    [Abstract] [Full Text] [Related] [New Search]