PDBsum entry 1ps8

Oxidoreductase

PDB id: 1ps8

Contents

Protein chain

357 a.a. *

Waters ×59

* Residue conservation analysis

PDB id:

1ps8

Name:

Oxidoreductase

Title:

Crystal structure of the r270k mutant of aspartate semialdehyde dehydrogenase from haemophilus influenzae

Structure:

Aspartate semialdehyde dehydrogenase. Chain: a. Synonym: asa dehydrogenase, asadh. Engineered: yes. Mutation: yes

Source:

Haemophilus influenzae. Organism_taxid: 727. Gene: asd. Expressed in: escherichia coli bl21. Expression_system_taxid: 511693.

Biol. unit:

Dimer (from PQS)

Resolution:

2.40Å R-factor: 0.224 R-free: 0.285

Authors:

J.Blanco,R.A.Moore,C.R.Faehnle,D.M.Coe,R.E.Viola

Key ref:

J.Blanco et al. (2004). The role of substrate-binding groups in the mechanism of aspartate-beta-semialdehyde dehydrogenase. Acta Crystallogr D Biol Crystallogr, 60, 1388-1395. PubMed id: 15272161 DOI: 10.1107/S0907444904012971

Date:

20-Jun-03 Release date: 27-Jul-04

Protein chain

P44801  (DHAS_HAEIN) -  Aspartate-semialdehyde dehydrogenase from Haemophilus influenzae (strain ATCC 51907 / DSM 11121 / KW20 / Rd)

Seq: 371 a.a.

Struc: 357 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: E.C.1.2.1.11 - aspartate-semialdehyde dehydrogenase.
• Pathway: Lysine biosynthesis (early stages)
• Reaction: L-aspartate 4-semialdehyde + phosphate + NADP⁺ = 4-phospho-L-aspartate + NADPH + H⁺

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

DOI no: 10.1107/S0907444904012971

Acta Crystallogr D Biol Crystallogr 60:1388-1395 (2004)

PubMed id: 15272161

The role of substrate-binding groups in the mechanism of aspartate-beta-semialdehyde dehydrogenase.

J.Blanco, R.A.Moore, C.R.Faehnle, D.M.Coe, R.E.Viola.

ABSTRACT

The reversible dephosphorylation of beta-aspartyl phosphate to L-aspartate-beta-semialdehyde (ASA) in the aspartate biosynthetic pathway is catalyzed by aspartate-beta-semialdehyde dehydrogenase (ASADH). The product of this reaction is a key intermediate in the biosynthesis of diaminopimelic acid, an integral component of bacterial cell walls and a metabolic precursor of lysine and also a precursor in the biosynthesis of threonine, isoleucine and methionine. The structures of selected Haemophilus influenzae ASADH mutants were determined in order to evaluate the residues that are proposed to interact with the substrates ASA or phosphate. The substrate Km values are not altered by replacement of either an active-site arginine (Arg270) with a lysine or a putative phosphate-binding group (Lys246) with an arginine. However, the interaction of phosphate with the enzyme is adversely affected by replacement of Arg103 with lysine and is significantly altered when a neutral leucine is substituted at this position. A conservative Glu243 to aspartate mutant does not alter either ASA or phosphate binding, but instead results in an eightfold increase in the Km for the coenzyme NADP. Each of the mutations is shown to cause specific subtle active-site structural alterations and each of these changes results in decreases in catalytic efficiency ranging from significant (approximately 3% native activity) to substantial (<0.1% native activity).

Selected figure(s)

Figure 1.
Figure 1 An abbreviated mechanism of the reaction catalyzed by aspartate -semialdehyde dehydrogenase.

Figure 4.
Figure 4 Overlay of the backbone drawings of native (light) and R103L mutant (dark) hiASADH structures. (a) The overall fold and backbone position of the native and mutant structures are essentially the same, except for the reorientation of a critical active-site loop (shown in red). (b) Disruption of the water-mediated hydrogen-bonding network between Arg103 and Asn135 in the R103L mutant that triggers this loop movement and shifts the position of the active-site Cys136 nucleophile. The calculation for the overlay was performed with XtalView and the drawing was produced using SPOCK.

The above figures are reprinted by permission from the IUCr: Acta Crystallogr D Biol Crystallogr (2004, 60, 1388-1395) copyright 2004.

Figures were selected by an automated process.