The MaoP/maoS Site-Specific System Organizes the Ori Region of the E. coli Chromosome into a Macrodomain
Fig 3
Identification of determinants required for Ori MD structuring.
(A) Effect of the presence of maoP in trans or the insertion of maoS at an ectopic position on deletions spanning the hdfR-yifE region (from coordinates 3944752–3948043) on Ori-3, Ori-4 and NSR-2 mobility. The extent of the region remaining upon the deletion is indicated. Mobility of markers Ori-3, Ori4 and NSR-3 are indicated; the loss of DNA constraint is indicated by “-” and DNA constraint indicated by “+”. (B) Programmed excision of chromosomal segments by site-specific recombination. The two att sites are integrated in the chromosome in the same orientation. Excisive recombination promoted by Int+Xis results in the excision and circularization of the intervening segment carrying attP or attB (depending on the order of attL and attR sites in the chromosome). attL and attR sites are flanked by the 5’ and 3’ parts of lacZ, respectively. The excised segment is devoid of replication origin and is not replicated. Integrative recombination between attP and attB occurs at very low frequency preventing fusion of the two molecules. (C) Travelled distance of Ori markers upon excision of different segment in the Ori region. The ori Td-3 segment carries maoS and maoP indicated by a red square. Mobility of markers Ori-3, Ori4 or Ori-6 are indicated; the loss of constraints is indicated by “-”and DNA constraint indicated by “+”.