Asymmetric Allosteric Signaling in Aspartate Transcarbamoylase

In the presence of CTP, UTP becomes an allosteric inhibitor of aspartate transcarbamoylase.

The allosteric control of aspartate transcarbamoylase (ATCase, EC 2.1.3.2) of Escherichia coli involves feedback inhibition by both CTP and UTP rather than just CTP alone. It has been known that CTP functions as a heterotropic inhibitor of catalysis; however, the inhibition by CTP alone is incomplete (50-70% at various aspartate concentrations) and there is only a partial occupancy of the allos...

Aspartate Transcarbamoylase of Aeromonas Hydrophila

Trapping and structure determination of an intermediate in the allosteric transition of aspartate transcarbamoylase.

X-ray crystallography and small-angle X-ray scattering (SAXS) in solution have been used to show that a mutant aspartate transcarbamoylase exists in an intermediate quaternary structure between the canonical T and R structures. Additionally, the SAXS data indicate a pH-dependent structural alteration consistent with either a pH-induced conformational change or a pH-induced alteration in the T t...

Can a simple model account for the allosteric transition of aspartate transcarbamoylase?

Stabilization of the R allosteric structure of Escherichia coli aspartate transcarbamoylase by disulfide bond formation.

Here we report the first use of disulfide bond formation to stabilize the R allosteric structure of Escherichia coli aspartate transcarbamoylase. In the R allosteric state, residues in the 240s loop from two catalytic chains of different subunits are close together, whereas in the T allosteric state they are far apart. By substitution of Ala-241 in the 240s loop of the catalytic chain with cyst...