Lateral Interactions Between FtsZ Protofilaments Mediated Z Ring Assembly

The prokaryotic tubulin homolog FtsZ polymerizes into protofilaments,which further assemble into higher-order structures at future division sites to form Z-ring.Z ring,the highly dynamic structure,is essential for bacterial cell division.The precise nature of interactions between FtsZ protofilaments that organize the Z-ring and their physiological significance remain enigmatic.In this study,we have solved two crystallographic structures of a pair of FtsZ protofilaments,demonstrating that they assemble in an antiparallel manner through the formation of two different inter-protofilament lateral interfaces.In vivo photocrosslinking studies demonstrated that such lateral interactons occur in linving cells,and disruption of the lateral interactions rendered cells unable to divide.The hydrophilic nature of these lateral interfaces implies weak interactions between protofilaments,which we propose is critical for enabling the rapid assembly dynamics required for Z-ring function.These results have fundamental implications for our understanding of bacterial cell division and for developint antibiotics that target this key process.