1N8F

Crystal structure of E24Q mutant of phenylalanine-regulated 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase (DAHP synthase) from Escherichia Coli in complex with Mn2+ and PEP

Summary for 1N8F

• Entry DOI: 10.2210/pdb1n8f/pdb
• Related: 1GG1 1KFL 1QR7
• Descriptor: DAHP Synthetase, MANGANESE (II) ION, SULFATE ION, ... (5 entities in total)
• Functional Keywords: (beta/alpha)8 barrel, metal binding protein
• Biological source: Escherichia coli
• Total number of polymer chains: 4
• Total formula weight: 153894.50

Authors

Shumilin, I.A.,Bauerle, R.,Kretsinger, R.H. (deposition date: 2002-11-20, release date: 2003-04-22, Last modification date: 2024-02-14)

Primary citation

Shumilin, I.A.,Bauerle, R.,Kretsinger, R.H.
The High-Resolution Structure of 3-Deoxy-D-arabino-heptulosonate-7-phosphate Synthase Reveals a Twist in the Plane of Bound Phosphoenolpyruvate
Biochemistry, 42:3766-3776, 2003

PubMed Abstract: 3-Deoxy-D-arabino-heptulosonate-7-phosphate synthase (DAHPS), the first enzyme of the aromatic biosynthetic pathway in microorganisms and plants, catalyzes the aldol-like condensation of phosphoenolpyruvate (PEP) and D-erythrose 4-phosphate (E4P) with the formation of DAHP. The native and the selenomethionine-substituted forms of the phenylalanine-regulated isozyme [DAHPS(Phe)] from Escherichia coli were crystallized in complex with PEP and a metal cofactor, Mn(2+), but the crystals displayed disorder in their unit cells, preventing satisfactory refinement. However, the crystal structure of the E24Q mutant form of DAHPS(Phe) in complex with PEP and Mn(2+) has been determined at 1.75 A resolution. Unlike the tetrameric wild-type enzyme, the E24Q enzyme is dimeric in solution, as a result of the mutational perturbation of four intersubunit salt bridges that are critical for tetramer formation. The protein chain conformation and subunit arrangement in the crystals of E24Q and wild-type DAHPS are very similar. However, the interaction of Mn(2+) and PEP in the enzymatically active E24Q mutant complex differs from the Pb(2+)-PEP and Mn(2+)-phosphoglycolate interactions in two enzymatically inactive wild-type complexes whose structures have been determined previously. The geometry of PEP bound in the active site of the E24Q enzyme deviates from planarity due to a 30 degrees twist of the carboxylate plane relative to the enol plane. In addition, seven water molecules are within contact distance of PEP, two of which are close enough to its C2 atom to serve as the nucleophile required in the reaction.

PubMed: 12667068
DOI: 10.1021/bi027257p

Experimental method

X-RAY DIFFRACTION (1.75 Å)