Separation of daughter cells during bacterial cell division requires that the septal cross wall be split by peptidoglycan hydrolases. In Streptococcus pneumoniae an essential protein termed PcsB is predicted to perform this critical operation. Recent evidence shows that the activity of PcsB is regulated by the transmembrane FtsEX complex. In this work the muralytic activity of PcsB is demonstrated for the first time. Furthermore, we report the crystal structure of full-length PcsB showing an unprecedented dimeric structure in which the unique V-shaped coiled-coil domain of each monomer acts as a molecular tweezers locking down the catalytic domain of its dimeric partner in an inactive configuration. This finding strongly suggests that the release of the catalytic domains requires an ATP-driven conformational change in the FtsEX complex, which is most likely conveyed towards the catalytic domains through a set of coordinated movements of the α-helices forming the coiled-coil domain of PcsB.


Sergio G. Bartual, Daniel Straume, Gro Anita Stamsås, Inés G. Muñoz, Carlos Alfonso, Martín Martínez-Ripoll, Leiv Sigve Håvarstein* & Juan A. Hermoso *

Structural basis of PcsB-mediated cell separation in Streptococcus pneumoniae

Nature Communications (2014). DOI: 10.1038/ncomms4842