A Polymerization-Associated Structural Switch in FtsZ That Enables Treadmilling of Model Filaments

Abstract

Bacterial cell division in many organisms involves a constricting cytokinetic ring that is orchestrated by the tubulin-like protein FtsZ. FtsZ forms dynamic filaments close to the membrane at the site of division that have recently been shown to treadmill around the division ring, guiding septal wall synthesis. Here, using X-ray crystallography of Staphylococcus aureus FtsZ (SaFtsZ), we reveal how an FtsZ can adopt two functionally distinct conformations, open and closed. The open form is found in SaFtsZ filaments formed in crystals and also in soluble filaments of Escherichia coli FtsZ as deduced by electron cryomicroscopy. The closed form is found within several crystal forms of two nonpolymerizing SaFtsZ mutants and corresponds to many previous FtsZ structures from other organisms. We argue that FtsZ’s conformational switch is polymerization-associated, driven by the formation of the longitudinal intersubunit interfaces along the filament. We show that such a switch provides explanations for both how treadmilling may occur within a single-stranded filament and why filament assembly is cooperative.

Conserved Dynamics of Chloroplast Cytoskeletal FtsZ Proteins Across Photosynthetic Lineages

“…Similar distinct curvatures have been observed for EcFtsZ (Lu and Erickson, 1999;Romberg et al, 2001;Srinivasan et al, 2008;Erickson et al, 2010). The structural basis for these differences remains unclear, though it is likely not a consequence of GTPase activity Wagstaff et al, 2017).…”

Bifunctional Immunity Proteins Protect Bacteria against FtsZ-Targeting ADP-Ribosylating Toxins

“…Treadmilling, or the preferential addition of new subunits at one end of a polymer coupled with loss at the opposite end requires a means of establishing filament polarity; how this is achieved for FtsZ filaments remains unclear (Krupka and Margolin, 2018). The ability of Tre1 to block FtsZ polymerization by modification of a residue located on one half of the monomer interaction interface could prove useful in testing different models for the mechanism by which polarity is produced (Wagstaff et al, 2017). …”

“…The model generated with MODELLER (https://salilab.org/modeller/) was based upon a crystal structure of Staphylococcus aureus FtsZ in the open conformation (PDB 5MN4) (Wagstaff et al, 2017). A trimeric FtsZ polymer was generated based on crystallographic symmetry.…”

“…Top, R174 in stick representation; middle, R174-ADPr in molecular surface representation; bottom, R174-ADPr in alternative rotomer that induces steric clashes between protomers. The FtsZ monomer structure was generated with MODELLER based on FtsZ from Staphylococcus aureus (PDB 5MN4) (Wagstaff et al, 2017) and the polymer was generated based on crystallographic symmetry. (G) Effect of adding FtsZ–ADPr at the indicated ratios to polymerization reactions of unmodified FtsZ.…”

The Molecular Machinery of Chloroplast Division

“…2; Box 1; Friedman and Nunnari, 2014;Addinall et al, 1996;Beech et al, 2000;Gilson et al, 2003;BilssonFilho et al, 2017;Osawa et al, 2009;Rothfield et al, 2005;Yang et al, 2017;Wagstaff et al, 2017;Strepp et al, 1997;Nishida et al, 2003;Lutkenhaus et al, 1980;Wang et al, 2017). Purified FtsZ undergoes GTPdependent self-assembly into single-stranded polymers called protofilaments.…”