FzlA, an essential regulator of FtsZ filament curvature, controls constriction rate during Caulobacter division

• Published in: Molecular microbiology 2018-01, Vol.107 (2), p.180-197
• Main Authors: Lariviere, Patrick J., Szwedziak, Piotr, Mahone, Christopher R., Löwe, Jan, Goley, Erin D.
• Format: Article
• Language: English
• Subjects: Bacteria; Bacterial proteins; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Caulobacter crescentus - cytology; Caulobacter crescentus - genetics; Caulobacter crescentus - physiology; Cell Cycle Proteins - chemistry; Cell Cycle Proteins - genetics; Cell Cycle Proteins - metabolism; Cell Division - genetics; Cell Division - physiology; Cell Membrane - metabolism; Cell Membrane - ultrastructure; Cell Wall - metabolism; Cell Wall - ultrastructure; Constrictions; Curvature; Cytoskeletal Proteins - chemistry; Cytoskeletal Proteins - genetics; Cytoskeletal Proteins - metabolism; Deformation; Filaments; Gene Library; GTP Phosphohydrolases - metabolism; Guanosine triphosphatases; Insertion; Metabolism; Peptidoglycan - metabolism; Peptidoglycans; Polymers; Protein Binding - genetics; Protein Conformation, beta-Strand; Protein Interaction Domains and Motifs - genetics; Septum; Tubulin
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/mmi.13876

Summary During bacterial division, polymers of the tubulin‐like GTPase FtsZ assemble at midcell to form the cytokinetic Z‐ring, which coordinates peptidoglycan (PG) remodeling and envelope constriction. Curvature of FtsZ filaments promotes membrane deformation in vitro, but its role in division in vivo remains undefined. Inside cells, FtsZ directs PG insertion at the division plane, though it is unclear how FtsZ structure and dynamics are mechanistically coupled to PG metabolism. Here we study FzlA, a division protein that stabilizes highly curved FtsZ filaments, as a tool for assessing the contribution of FtsZ filament curvature to constriction. We show that in Caulobacter crescentus, FzlA must bind to FtsZ for division to occur and that FzlA‐mediated FtsZ curvature is correlated with efficient division. We observed that FzlA influences constriction rate, and that this activity is associated with its ability to bind and curve FtsZ polymers. Further, we found that a slowly constricting fzlA mutant strain develops ‘pointy’ poles, suggesting that FzlA influences the relative contributions of radial versus longitudinal PG insertion at the septum. These findings implicate FzlA as a critical coordinator of envelope constriction through its interaction with FtsZ and suggest a functional link between FtsZ curvature and efficient constriction in C. crescentus. FzlA is an essential regulator of FtsZ protofilament curvature in Caulobacter crescentus. Through a structure‐function approach, we identify mutants of FzlA abrogated in their interactions with FtsZ with regards to binding and protofilament curvature, which correlate with shape, growth and division defects. Importantly, disruption of the FzlA‐FtsZ interaction causes a decrease in constriction rate. We propose that FzlA is required to activate constriction for cell division in C. crescentus through its interaction with FtsZ. Additionally, we provide evidence for a functional link between FtsZ curvature and efficient constriction.