Treadmilling analysis reveals new insights into dynamic FtsZ ring architecture

Abstract

FtsZ, the primary protein of the bacterial Z ring guiding cell division, has been recently shown to engage in intriguing treadmilling dynamics along the circumference of the division plane. When coreconstituted in vitro with FtsA, one of its natural membrane anchors, on flat supported membranes, these proteins assemble into dynamic chiral vortices compatible with treadmilling of curved polar filaments. Replacing FtsA by a membrane-targeting sequence (mts) to FtsZ, we have discovered conditions for the formation of dynamic rings, showing that the phenomenon is intrinsic to FtsZ. Ring formation is only observed for a narrow range of protein concentrations at the bilayer, which is highly modulated by free Mg2+ and depends upon guanosine triphosphate (GTP) hydrolysis. Interestingly, the direction of rotation can be reversed by switching the mts from the C-terminus to the N-terminus of the protein, implying that the filament attachment must have a perpendicular component to both curvature and polarity. Remarkably, this chirality switch concurs with previously shown inward or outward membrane deformations by the respective FtsZ mutants. Our results lead us to suggest an intrinsic helicity of FtsZ filaments with more than one direction of curvature, supporting earlier hypotheses and experimental evidence.

Functional Modules of Minimal Cell Division for Synthetic Biology

“…[71,72] It is also a cytosolic protein and needs either FtsA or ZipA in order to attach to the membrane in vivo. [76] These results could be used in the field of bottom-up synthetic biology to design a minimal divisome consisting of only two proteins: ZipA acting as a membrane anchor to transmit the motor force generated by FtsZ polymerization as has been shown by vesicle shrinkage and membrane invagination in vitro. [57] ZipA is integrated into the membrane via an N-terminal domain and also contains a C-terminal FtsZ-binding domain, both connected via a flexible linker.…”

“…One big player in this context and one of the best studied prokaryotic division proteins to date is FtsZ, which is required for septum formation but does not itself perform the septation process. [76] FtsZ shows outstanding treadmilling dynamics in vivo as well as in vitro in circular polymer structures with a diameter of ≈1 µm. [71,72] It is also a cytosolic protein and needs either FtsA or ZipA in order to attach to the membrane in vivo.…”

“…It is highly conserved in the bacterial domain and the ancestor of eukaryotic tubulin. [76] In combination with recent studies in E. coli [77] and B. subtilis [78] on the correlation between treadmilling dynamics and peptidoglycan synthesis, a new focus on the FtsZ structure and its dynamics can now be formulated, as well as provide insight into the mechanical aspects of bacterial cell division. FtsA is part of the actin-family and contains an amphipathic helix that is believed to mediate its binding to the membrane.…”

“…[57] ZipA is integrated into the membrane via an N-terminal domain and also contains a C-terminal FtsZ-binding domain, both connected via a flexible linker. [76,[79][80][81] [76] FtsZ shows outstanding treadmilling dynamics in vivo as well as in vitro in circular polymer structures with a diameter of ≈1 µm.…”

Regulation of Streptococcus pneumoniae FtsZ assembly by divalent cations: paradoxical effects of Ca2+ on the nucleation and bundling of FtsZ polymers

“…FtsZ, a homolog of the eukaryotic cytoskeletal protein, tubulin [5,6], is the chief constituent of the machinery that coordinates the partitioning of the bacterial cells. FtsZ also displays treadmilling behavior, which emphasizes the importance of the GTPase activity for the formation and functioning of the Zring in bacteria [12][13][14]. The Zring formation is orchestrated by coordinated actions of several positive and negative regulators of FtsZ assembly [8][9][10][11].…”