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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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Representative examples of raw data from three different concentrations of CtpS incubated in activity buffer included in Figure 1B.Light scattering (polymerization) is shown in blue and transmittance data (CTP accumulation) is shown in red. (A) 100 nM CtpS (below polymerization threshold). (B) 2 µM CtpS (at polymerization threshold). (C) 5 µM CtpS (above polymerization threshold).DOI:http://dx.doi.org/10.7554/eLife.03638.005
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fig1s2: Representative examples of raw data from three different concentrations of CtpS incubated in activity buffer included in Figure 1B.Light scattering (polymerization) is shown in blue and transmittance data (CTP accumulation) is shown in red. (A) 100 nM CtpS (below polymerization threshold). (B) 2 µM CtpS (at polymerization threshold). (C) 5 µM CtpS (above polymerization threshold).DOI:http://dx.doi.org/10.7554/eLife.03638.005

Mentions: “The cellular level of CtpS protein in E. coli grown in minimal media was 2.3 μM (Figure 1–figure supplement 2), indicating that the CtpS polymerization observed in vitro occurs within a physiologically relevant concentration regime.” This is actually right at the borderline of where in vitro activity starts to decrease. I would conclude that the proposed regulation mechanism by assembly is on the borderline of physiological significance.


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)

Representative examples of raw data from three different concentrations of CtpS incubated in activity buffer included in Figure 1B.Light scattering (polymerization) is shown in blue and transmittance data (CTP accumulation) is shown in red. (A) 100 nM CtpS (below polymerization threshold). (B) 2 µM CtpS (at polymerization threshold). (C) 5 µM CtpS (above polymerization threshold).DOI:http://dx.doi.org/10.7554/eLife.03638.005
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig1s2: Representative examples of raw data from three different concentrations of CtpS incubated in activity buffer included in Figure 1B.Light scattering (polymerization) is shown in blue and transmittance data (CTP accumulation) is shown in red. (A) 100 nM CtpS (below polymerization threshold). (B) 2 µM CtpS (at polymerization threshold). (C) 5 µM CtpS (above polymerization threshold).DOI:http://dx.doi.org/10.7554/eLife.03638.005
Mentions: “The cellular level of CtpS protein in E. coli grown in minimal media was 2.3 μM (Figure 1–figure supplement 2), indicating that the CtpS polymerization observed in vitro occurs within a physiologically relevant concentration regime.” This is actually right at the borderline of where in vitro activity starts to decrease. I would conclude that the proposed regulation mechanism by assembly is on the borderline of physiological significance.

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