PDBsum entry 2aal

Lyase

PDB id: 2aal

Contents

Protein chains

(+ 0 more) 129 a.a. *

Ligands

MLI ×6

Waters ×956

* Residue conservation analysis

PDB id:

2aal

Name:

Lyase

Title:

Crystal structures of the wild-type, mutant-p1a and inactivated malonate semialdehyde decarboxylase: a structural basis for the decarboxylase and hydratase activities

Structure:

Malonate semialdehyde decarboxylase. Chain: a, b, c, d, e, f. Engineered: yes

Source:

Pseudomonas pavonaceae. Organism_taxid: 47881. Strain: 170. Gene: msad. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Biol. unit:

Trimer (from PQS)

Resolution:

1.65Å R-factor: 0.186 R-free: 0.239

Authors:

J.J.Almrud,G.J.Poelarends,W.H.Johnson Jr.,H.Serrano,M.L.Hackert, C.P.Whitman

Key ref:

J.J.Almrud et al. (2005). Crystal structures of the wild-type, P1A mutant, and inactivated malonate semialdehyde decarboxylase: a structural basis for the decarboxylase and hydratase activities. Biochemistry, 44, 14818-14827. PubMed id: 16274229 DOI: 10.1021/bi051383m

Date:

13-Jul-05 Release date: 22-Nov-05

Protein chains

Q9EV83  (Q9EV83_PSEPV) -  Malonate semialdehyde decarboxylase from Pseudomonas pavonaceae

Seq: 130 a.a.

Struc: 129 a.a.*

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

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1021/bi051383m

Biochemistry 44:14818-14827 (2005)

PubMed id: 16274229

Crystal structures of the wild-type, P1A mutant, and inactivated malonate semialdehyde decarboxylase: a structural basis for the decarboxylase and hydratase activities.

J.J.Almrud, G.J.Poelarends, W.H.Johnson, H.Serrano, M.L.Hackert, C.P.Whitman.

ABSTRACT

Malonate semialdehyde decarboxylase (MSAD) from Pseudomonas pavonaceae 170 is a tautomerase superfamily member that converts malonate semialdehyde to acetaldehyde by a mechanism utilizing Pro-1 and Arg-75. Pro-1 and Arg-75 have also been implicated in the hydratase activity of MSAD in which 2-oxo-3-pentynoate is processed to acetopyruvate. Crystal structures of MSAD (1.8 A resolution), the P1A mutant of MSAD (2.7 A resolution), and MSAD inactivated by 3-chloropropiolate (1.6 A resolution), a mechanism-based inhibitor activated by the hydratase activity of MSAD, have been determined. A comparison of the P1A-MSAD and MSAD structures reveals little geometric alteration, indicating that Pro-1 plays an important catalytic role but not a critical structural role. The structures of wild-type MSAD and MSAD covalently modified at Pro-1 by 3-oxopropanoate, the adduct resulting from the incubation of MSAD and 3-chloropropiolate, implicate Asp-37 as the residue that activates a water molecule for attack at C-3 of 3-chloropropiolate to initiate a Michael addition of water. The interactions of Arg-73 and Arg-75 with the C-1 carboxylate group of the adduct suggest these residues polarize the alpha,beta-unsaturated acid and facilitate the addition of water. On the basis of these structures, a mechanism for the inactivation of MSAD by 3-chloropropiolate can be formulated along with mechanisms for the decarboxylase and hydratase activities. The results also provide additional evidence supporting the hypothesis that MSAD and trans-3-chloroacrylic acid dehalogenase, a tautomerase superfamily member preceding MSAD in the trans-1,3-dichloropropene degradation pathway, diverged from a common ancestor but retained the key elements for the conjugate addition of water.