scholarly journals Reciprocal allostery arising from a bi-enzyme assembly controls aromatic amino acid biosynthesis in Prevotella nigrescens

2021 ◽  
Author(s):  
Yu Bai ◽  
Emily J. Parker
Keyword(s):  
Amino Acid ◽  
Branch Point ◽  
Aromatic Amino Acid ◽  
Amino Acid Biosynthesis ◽  
Chorismate Mutase ◽  
Dual Function ◽  
Acid Biosynthesis ◽  
Aromatic Amino Acid Biosynthesis ◽  
Prevotella Nigrescens ◽  
Interdomain Interactions

ABSTRACTModular protein assembly has been widely reported as a mechanism for constructing allosteric machinery. Recently, a distinctive allosteric system has been identified in a bi-enzyme assembly comprising a 3-deoxy-d-arabino heptulosonate-7-phosphate synthase (DAH7PS) and chorismate mutase (CM). These enzymes catalyze the first and branch point reactions of aromatic amino acid biosynthesis in the bacterium Prevotella nigrescens (PniDAH7PS), respectively. The interactions between these two distinct catalytic domains support functional inter-reliance within this bifunctional enzyme. The binding of prephenate, the product of CM-catalyzed reaction, to the CM domain is associated with a striking rearrangement of overall protein conformation that alters the interdomain interactions and allosterically inhibits the DAH7PS activity. In this study, we observed allosteric activation of CM activity in the presence of all DAH7PS substrates. Using small angle X-ray scattering (SAXS) experiments we show that changes in overall protein conformations and dynamics are associated with the presence of different DAH7PS substrates and the allosteric inhibitor prephenate. Furthermore, we have identified an extended interhelix loop located in CM domain, loopC320-F333, as a crucial segment for the interdomain structural and catalytic communications. Our results suggest that the dual function enzyme PniDAH7PS contains a reciprocal allosteric system between the two enzymatic moieties, as a result of this bidirectional interdomain communication. This arrangement allows for a complex feedback and feedforward system for control of pathway flux by connecting the initiation and branch point of aromatic amino acid biosynthesis.

Computational investigations of allostery in aromatic amino acid biosynthetic enzymes

2021 ◽  
Author(s):  
Wanting Jiao
Keyword(s):  
Amino Acid ◽  
Aromatic Amino Acid ◽  
Amino Acid Biosynthesis ◽  
Chorismate Mutase ◽  
Tryptophan Synthase ◽  
Biosynthesis Pathway ◽  
Acid Biosynthesis ◽  
Computational Tools ◽  
Aromatic Amino Acid Biosynthesis ◽  
Allosteric Mechanisms

Allostery, in which binding of ligands to remote sites causes a functional change in the active sites, is a fascinating phenomenon observed in enzymes. Allostery can occur either with or without significant conformational changes in the enzymes, and the molecular basis of its mechanism can be difficult to decipher using only experimental techniques. Computational tools for analyzing enzyme sequences, structures, and dynamics can provide insights into the allosteric mechanism at the atomic level. Combining computational and experimental methods offers a powerful strategy for the study of enzyme allostery. The aromatic amino acid biosynthesis pathway is essential in microorganisms and plants. Multiple enzymes involved in this pathway are sensitive to feedback regulation by pathway end products and are known to use allostery to control their activities. To date, four enzymes in the aromatic amino acid biosynthesis pathway have been computationally investigated for their allosteric mechanisms, including 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase, anthranilate synthase, chorismate mutase, and tryptophan synthase. Here we review the computational studies and findings on the allosteric mechanisms of these four enzymes. Results from these studies demonstrate the capability of computational tools and encourage future computational investigations of allostery in other enzymes of this pathway.

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