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Molecular and General Genetics MGG

, Volume 261, Issue 4–5, pp 707–715 | Cite as

Mobilisation of the streptococcal plasmid pMV158: interactions of MobM protein with its cognate oriT DNA region

  • E. Grohmann
  • L. M. Guzmán
  • M. Espinosa
ORIGINAL PAPER

Abstract

The streptococcal plasmid pMV158 encodes the relaxase protein, MobM, involved in its mobilisation. Purified MobM protein specifically cleaved supercoiled or single-stranded DNA containing the plasmid origin of transfer, oriT. Gel retardation and DNase I footprinting assays performed with DNA fragments containing the plasmid oriT provided evidence for specific binding of MobM by oriT DNA. Dissection of the MobM-binding sequence revealed that the oriT region protected by MobM spanned 28 nucleotides, and includes an inversely repeated sequence, termed IR2. MobM exhibits a high degree of similarity with the mob gene product of the Streptococcus ferus plasmid pVA380-1. Although the origins of transfer of pMV158 and pVA380-1 show 20% sequence divergence in a 24-bp sequence included in their oriT regions, the pMV158 MobM was able to cleave a supercoiled derivative of pVA380-1 in vitro.

Key words Mobilisation protein Plasmid pMV158 Site- and strand-specific cleavage Origin of transfer DNA-protein interactions 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • E. Grohmann
    • 1
  • L. M. Guzmán
    • 1
  • M. Espinosa
    • 1
  1. 1.Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Velázquez 144, E-28006 Madrid, Spain e-mail: mespinosa@fresno.csic.es Tel.: +34-91-5611800 ext. 4209; Fax: +34-91-5627518ES

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