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Large-scale filament formation inhibits the activity of CTP synthetase.

Barry RM, Bitbol AF, Lorestani A, Charles EJ, Habrian CH, Hansen JM, Li HJ, Baldwin EP, Wingreen NS, Kollman JM, Gitai Z - Elife (2014)

Bottom Line: Structure-guided mutagenesis and mathematical modeling further indicate that coupling activity to polymerization promotes cooperative catalytic regulation.This previously uncharacterized regulatory mechanism is important for cellular function since a mutant that disrupts CtpS polymerization disrupts E. coli growth and metabolic regulation without reducing CTP levels.We propose that regulation by large-scale polymerization enables ultrasensitive control of enzymatic activity while storing an enzyme subpopulation in a conformationally restricted form that is readily activatable.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology, Princeton University, Princeton, United States.

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Cryo-EM reconstruction of CtpS filaments.(A) A field of CtpS filaments in cryo-EM. (B) Cryo-EM image of a single CtpS filament. (C) The reconstruction of CtpS filament shown at 8.4 Å resolution. In addition to the refined helical symmetry, local 2-2-2 point group symmetry was imposed on each helical subunit. (D) The resolution of the final reconstruction was estimated in two ways: the standard even-odd half volume test (blue), and a comparison of the cryo-EM structure to the atomic model (red). For both measures, the resolution is estimated at 10.4 Å by the 0.5 cutoff criterion, and 8.4 Å by the 0.143 criterion.DOI:http://dx.doi.org/10.7554/eLife.03638.018
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fig3s1: Cryo-EM reconstruction of CtpS filaments.(A) A field of CtpS filaments in cryo-EM. (B) Cryo-EM image of a single CtpS filament. (C) The reconstruction of CtpS filament shown at 8.4 Å resolution. In addition to the refined helical symmetry, local 2-2-2 point group symmetry was imposed on each helical subunit. (D) The resolution of the final reconstruction was estimated in two ways: the standard even-odd half volume test (blue), and a comparison of the cryo-EM structure to the atomic model (red). For both measures, the resolution is estimated at 10.4 Å by the 0.5 cutoff criterion, and 8.4 Å by the 0.143 criterion.DOI:http://dx.doi.org/10.7554/eLife.03638.018

Mentions: To better understand the mechanism of enzymatic inhibition by polymerization, we determined the structure of the CtpS filament by cryo-electron microscopy at 8.4 Å resolution (Figure 3—figure supplement 1). The repeating subunits of the filament are X-shaped CtpS tetramers (Figure 3A). The helical symmetry of the filament results in CtpS tetramers stacked atop one another with the arms of the adjacent Xs interdigitated. The 222 point group symmetry of the tetramer is maintained within the filament, resulting in overall twofold symmetry both along and perpendicular to the helical axis. A significant effect of this unusual symmetry is that, unlike many biological polymers, CtpS filaments are apolar.10.7554/eLife.03638.017Figure 3.Cryo-EM structure of CtpS filaments at 8.4 Å resolution.


Large-scale filament formation inhibits the activity of CTP synthetase.

Barry RM, Bitbol AF, Lorestani A, Charles EJ, Habrian CH, Hansen JM, Li HJ, Baldwin EP, Wingreen NS, Kollman JM, Gitai Z - Elife (2014)

Cryo-EM reconstruction of CtpS filaments.(A) A field of CtpS filaments in cryo-EM. (B) Cryo-EM image of a single CtpS filament. (C) The reconstruction of CtpS filament shown at 8.4 Å resolution. In addition to the refined helical symmetry, local 2-2-2 point group symmetry was imposed on each helical subunit. (D) The resolution of the final reconstruction was estimated in two ways: the standard even-odd half volume test (blue), and a comparison of the cryo-EM structure to the atomic model (red). For both measures, the resolution is estimated at 10.4 Å by the 0.5 cutoff criterion, and 8.4 Å by the 0.143 criterion.DOI:http://dx.doi.org/10.7554/eLife.03638.018
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4126345&req=5

fig3s1: Cryo-EM reconstruction of CtpS filaments.(A) A field of CtpS filaments in cryo-EM. (B) Cryo-EM image of a single CtpS filament. (C) The reconstruction of CtpS filament shown at 8.4 Å resolution. In addition to the refined helical symmetry, local 2-2-2 point group symmetry was imposed on each helical subunit. (D) The resolution of the final reconstruction was estimated in two ways: the standard even-odd half volume test (blue), and a comparison of the cryo-EM structure to the atomic model (red). For both measures, the resolution is estimated at 10.4 Å by the 0.5 cutoff criterion, and 8.4 Å by the 0.143 criterion.DOI:http://dx.doi.org/10.7554/eLife.03638.018
Mentions: To better understand the mechanism of enzymatic inhibition by polymerization, we determined the structure of the CtpS filament by cryo-electron microscopy at 8.4 Å resolution (Figure 3—figure supplement 1). The repeating subunits of the filament are X-shaped CtpS tetramers (Figure 3A). The helical symmetry of the filament results in CtpS tetramers stacked atop one another with the arms of the adjacent Xs interdigitated. The 222 point group symmetry of the tetramer is maintained within the filament, resulting in overall twofold symmetry both along and perpendicular to the helical axis. A significant effect of this unusual symmetry is that, unlike many biological polymers, CtpS filaments are apolar.10.7554/eLife.03638.017Figure 3.Cryo-EM structure of CtpS filaments at 8.4 Å resolution.

Bottom Line: Structure-guided mutagenesis and mathematical modeling further indicate that coupling activity to polymerization promotes cooperative catalytic regulation.This previously uncharacterized regulatory mechanism is important for cellular function since a mutant that disrupts CtpS polymerization disrupts E. coli growth and metabolic regulation without reducing CTP levels.We propose that regulation by large-scale polymerization enables ultrasensitive control of enzymatic activity while storing an enzyme subpopulation in a conformationally restricted form that is readily activatable.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology, Princeton University, Princeton, United States.

Show MeSH
Related in: MedlinePlus