Condensins are key mediators of chromosome condensation across organisms. Like other condensins, the bacterial MukBEF condensin complex consists of an SMC family protein dimer containing two ATPase head domains, MukB, and two interacting subunits, MukE and MukF. We report complete structural views of the intersubunit interactions of this condensin along with ensuing studies that reveal a role for the ATPase activity of MukB. MukE and MukF together form an elongated dimeric frame, and MukF's C-terminal winged-helix domains (C-WHDs) bind MukB heads to constitute closed ring-like structures. Surprisingly, one of the two bound C-WHDs is forced to detach upon ATP-mediated engagement of MukB heads. This detachment reaction depends on the linker segment preceding the C-WHD, and mutations on the linker restrict cell growth. Thus ATP-dependent transient disruption of the MukB-MukF interaction, which creates openings in condensin ring structures, is likely to be a critical feature of the functional mechanism of condensins.
Bibliographical noteFunding Information:
This study was supported by Creative Research Initiatives (Center for Biomolecular Interaction) of MOST/KOSEF and partly by Core Research Program of POSTECH. J.-H.L., M.-K.S., H.-C.S., B.K. and K.-H.L. were supported by the Brain Korea 21 Project. This study made use of the beamline 4A at the Pohang Accelerator Laboratory in Korea, the beamline BL-5A at Photon Factory in Japan and the Brookhaven National Laboratory/Biology beamline X29 at the National Synchrotron Light Source in USA. The BNL Biology/PX Mail-in program is supported by the NIH institute, National Center for Research Resources.
ASJC Scopus subject areas
- General Biochemistry,Genetics and Molecular Biology