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FtsZ Protofilaments Use a Hinge-Opening Mechanism for Constrictive Force Generation

24-09-2013

The essential bacterial protein FtsZ is a guanosine triphosphatase that self-assembles into a structure at the division

site termed the “Z ring”. During cytokinesis, the Z ring exerts a constrictive force on the membrane by using the

chemical energy of guanosine triphosphate hydrolysis. However, the structural basis of this constriction remains

unresolved. Here, we present the crystal structure of a guanosine diphosphate–boundMycobacterium tuberculosis

FtsZ protofilament, which exhibits a curved conformational state. The structure reveals a longitudinal interface that

is important for function. The protofilament curvature highlights a hydrolysis-dependent conformational switch at the

T3 loop that leads to longitudinal bending between subunits, which could generate sufficient force to drive cytokinesis.

The research was conducted at the SSRF beamline 17U1.

GTP hydrolysis induces a straight-to-curved conformational switch at the longitudinal interface.