3-deoxyarabinoheptulosanate-7-phosphate synthase

3-deoxyarabinoheptulosanate-7-phosphate synthase (E. coli)
Ribbon model of 3-deoxyarabinoheptulosanate-7-phosphate synthase
other names	DAHP synthase
Existing structure data : PDB  1GG1 , PDB  1KFL , PDB  1N8F
Mass / length primary structure	356 amino acids , 38,804 Da
Secondary to quaternary structure	Tetramer
Cofactor	a divalent metal ion
Isoforms	3
Identifier
Gene name (s)	aroF, aroG, aroH
External IDs	UniProt :  P00888 CAS number : 9026-94-2
Enzyme classification
EC, category	2.5.1.54 ,  transferase
Response type	condensation
Substrate	Erythrose-4-phosphate + PEP + H 2 O
Products	3-deoxyarabinoheptulosanate-7-phosphate + P i
Occurrence
Homology family	HOG000220501
Parent taxon	Bacteria , Eukaryota
Orthologue (E. coli)
Entrez	947084
UniProt	P00888
Refseq (protein)	NP_417092.1
PubMed search	947084

3-deoxyarabinoheptulosanate-7-phosphate synthase ( DAHP synthase ) is an enzyme that mostly degenerates in bacteria , but also in eukaryotes and archaea . The enzyme belongs to the so-called DAHP synthases, which catalyze the first enzymatic reaction of the shikimic acid pathway . Within the DAHP synthases, a distinction is made between two different classes, the enzymes of which are produced by organisms from different domains . Class I is made up of DAHP synthases from microorganisms, including 3-deoxyarabinoheptulosanate-7-phosphate synthase, and class II from plants, although some class II enzymes can also be produced by microbial eukaryotes and bacteria.

properties

Reaction mechanism

In addition to catalyzing the first enzymatic reaction in the shikimic acid pathway, the enzyme is also responsible for regulating the carbon content during this reaction, which is primarily controlled by feedback inhibition (product inhibition ) and transcriptionally .

There are three such isoenzymes in Escherichia coli , each of which is inhibited by one of the three aromatic amino acids .

From a structural point of view, there are no major differences between the isoenzymes. For example, phenylalanine- regulated DAHP synthases have so-called TIM barrels (German: TIM-Fass ) as monomers, which consist of eight parallel β-sheets and are connected to each other with eight helices , with another β-sheet near the C terminus is located. The allosteric center for feedback inhibition consists of the residues of two adjacent subunits, which are located approximately 20 Å from the active center .

reaction

Erythrose-4-phosphate and phosphoenolpyruvate are reacted with water to form 3-deoxyarabinoheptulosanate-7-phosphate and phosphate .

use

The enzyme has both agricultural and biotechnological potential. When a bacterial gene was expressed in a transgenic cress , elevated levels of metabolic intermediates and phytochemicals were discovered that can help overcome bottlenecks in primary and secondary metabolic pathways. Phosphoenolpyruvate is used for many biosynthetic reactions, for example in the fermentation of glucose , whereby PEP is consumed by the phosphotransferase system. Mutant E. coli bacteria can transport glucose without consuming PEP, so several aromatic compounds can be produced using the increased yield of PEP.

Individual evidence

1. ↑ GE Walker, B. Dunbar, l. S. Hunter, HG Nimmo, JR Coggins: Evidence for a novel class of microbial 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase in Streptomyces coelicolor A3 (2), Streptomyces rimosus and Neurospora crassa. In: Microbiology. 142, 1996, p. 1973, doi: 10.1099 / 13500872-142-8-1973 .
2. ↑ R. Schoner, KM Herrmann: 3-Deoxy-D-arabino-heptulosonate 7-phosphate synthase. Purification, properties, and kinetics of the tyrosine-sensitive isoenzymes from Escherichia coli. In: The Journal of biological chemistry. Volume 251, Number 18, September 1976, pp. 5440-5447, PMID 9387 .
3. ↑ IA Shumilin, RH Kretsinger, RH Bauerle: Crystal structure of phenylalanine-regulated 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase from Escherichia coli. In: Structure. Volume 7, Number 7, July 1999, pp. 865-875, PMID 10425687 .
4. ↑ IA Shumilin, C. Zhao, R. Bauerle, RH Kretsinger: Allosteric inhibition of 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase age the coordination of Both substrates. In: Journal of molecular biology. Volume 320, Number 5, July 2002, pp. 1147-1156, PMID 12126632 .
5. ↑ N. Flores, J. Xiao, A. Berry, F. Bolivar, F. Valle: Pathway engineering for the production of aromatic compounds in Escherichia coli. In: Nature Biotechnology . Volume 14, Number 5, May 1996, pp. 620-623, doi: 10.1038 / nbt0596-620 , PMID 9630954 .