The metabolic enzyme CTP synthase forms cytoskeletal filaments.
Filament-forming cytoskeletal proteins are essential for the structure and organization of all cells. Bacterial homologues of the major eukaryotic cytoskeletal families have now been discovered, but studies suggest that yet more remain to be identified. We demonstrate that the metabolic enzyme CTP synthase (CtpS) forms filaments in Caulobacter crescentus. CtpS is bifunctional, as the filaments it forms regulate the curvature of C. crescentus cells independently of its catalytic function. The morphogenic role of CtpS requires its functional interaction with the intermediate filament, crescentin (CreS). Interestingly, the Escherichia coli CtpS homologue also forms filaments both in vivo and in vitro, suggesting that CtpS polymerization may be widely conserved. E. coli CtpS can replace the enzymatic and morphogenic functions of C. crescentus CtpS, indicating that C. crescentus has adapted a conserved filament-forming protein for a secondary role. These results implicate CtpS as a novel bifunctional member of the bacterial cytoskeleton and suggest that localization and polymerization may be important properties of metabolic enzymes.
Ingerson-Mahar
Michael
M
Department of Molecular Biology, Princeton University, Lewis Thomas Labs, Washington Road, Princeton, NJ 08544, USA.
Briegel
Ariane
A
Werner
John N
JN
Jensen
Grant J
GJ
Gitai
Zemer
Z
D001426:Bacterial Proteins / Q000378:metabolism*; D019731:Carbon-Nitrogen Ligases / Q000378:metabolism*; D016935:Caulobacter crescentus / Q000201:enzymology / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D008858:Microscopy, Phase-Contrast; D011485:Protein Binding
D001426:Bacterial Proteins; D019731:Carbon-Nitrogen Ligases; C019951:CTP synthetase