Acyl carrier protein promotes MukBEF action in Escherichia coli chromosome organization-segregation

Abstract

Structural Maintenance of Chromosomes (SMC) complexes act ubiquitously to compact DNA linearly, thereby facilitating chromosome organization-segregation. SMC proteins have a conserved architecture, with a dimerization hinge and an ATPase head domain separated by a long antiparallel intramolecular coiled-coil. Dimeric SMC proteins interact with essential accessory proteins, kleisins that bridge the two subunits of an SMC dimer, and HAWK/KITE proteins that interact with kleisins. The ATPase activity of the Escherichia coli SMC protein, MukB, which is essential for its in vivo function, requires its interaction with the dimeric kleisin, MukF that in turn interacts with the KITE protein, MukE. Here we demonstrate that, in addition, MukB interacts specifically with Acyl Carrier Protein (AcpP) that has essential functions in fatty acid synthesis. We characterize the AcpP interaction at the joint of the MukB coiled-coil and show that the interaction is necessary for MukB ATPase and for MukBEF function in vivo.

Inter- and intra-Subunit interactions driving the MukBEF ATPase

“…It has been reported that the MukB ATPase activity is DNA-independent and is, in fact, inhibited somewhat by double-stranded DNA (31), whereas Zawadzka et al (41) showed that DNA neutralized to some extent the effect of MukE-mediated inhibition of the MukBF ATPase activity. However, in our current study, using saturating concentrations of AcpP, which is required for the MukBF ATPase activity (25), we find no effect of DNA on the ATPase activity of either the MukBF or MukBEF complexes.…”

“…Optimal Conditions for the MukB ATPase Activity-MukB alone hydrolyzes ATP (26), and this activity is stimulated by MukF (27,28), whereas the MukBF ATPase is inhibited by MukE (27,28). AcpP was known to interact with MukB (26,29,30), but the significance of this interaction remained obscure until Prince et al (25) demonstrated that AcpP was required for maximal MukBF ATPase activity. This observation indicated that some previous observations of the MukB ATPase activity might have been affected by the extent to which the MukB preparation was saturated with AcpP.…”

“…This bent conformation of MukB had been reported previously (24). AcpP has also very recently been shown to be required for the MukB ATPase (25).…”

Intersubunit and intrasubunit interactions driving the MukBEF ATPase

“…AcpP was known to interact with MukB ( 27 , 30 , 31 ), but the significance of this interaction remained obscure until Prince et al. ( 26 ) demonstrated that AcpP was required for maximal MukBF ATPase activity. This observation indicated that some previous observations of the MukB ATPase activity might have been affected by the extent to which the MukB preparation was saturated with AcpP.…”

“…This bent conformation of MukB had been reported previously ( 13 ). AcpP has also very recently been shown to be required for the MukB ATPase ( 26 ).…”