Antagonistic interactions of kleisins and DNA with bacterial Condensin MukB.
MukBEF is a bacterial SMC (structural maintenance of chromosome) complex required for faithful chromosome segregation in Escherichia coli. The SMC subunit of the complex, MukB, promotes DNA condensation in vitro and in vivo; however, all three subunits are required for the function of MukBEF. We report here that MukEF disrupts MukB x DNA complex. Preassembled MukBEF was inert in DNA binding or reshaping. Similarly, the association of MukEF with DNA-bound MukB served to displace MukB from DNA. When purified from cells, MukBEF existed as a mixture of MukEF-saturated and unsaturated complexes. The holoenzyme was unstable and could only bind DNA upon dissociation of MukEF. The DNA reshaping properties of unsaturated MukBEF were identical to those of MukB. Furthermore, the unsaturated MukBEF was stable and proficient in DNA binding. These results support the view that kleisins are not directly involved in DNA binding but rather bridge distant DNA-bound MukBs.
Petrushenko
Zoya M
ZM
Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, USA.
Lai
Chien-Hung
CH
Rybenkov
Valentin V
VV
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D020090:Chromosome Segregation; D004269:DNA, Bacterial / Q000737:chemistry*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism / Q000502:physiology*
D002868:Chromosomal Proteins, Non-Histone; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C067035:MukB protein, E coli; D046912:Multiprotein Complexes; D012097:Repressor Proteins; C108312:condensin complexes; C087115:mukE protein, E coli; C087116:mukF protein, E coli; D000251:Adenosine Triphosphatases