PDBsum entry 1k4j

Ligase

PDB id: 1k4j

Contents

Protein chain

193 a.a. *

Ligands

REO ×7

Waters ×21

* Residue conservation analysis

PDB id:

1k4j

Name:

Ligase

Title:

Crystal structure of the acyl-homoserinelactone synthase esai complexed with rhenate

Structure:

Acyl-homoserinelactone synthase esai. Chain: a. Engineered: yes

Source:

Pantoea stewartii subsp. Stewartii. Organism_taxid: 66271. Strain: subsp. Stewartii. Gene: esai/esar cluster. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

2.50Å R-factor: 0.216 R-free: 0.275

Authors:

W.T.Watson,T.D.Minogue,D.L.Val,S.Beck Von Bodman,M.E.A.Churchill

Key ref:

W.T.Watson et al. (2002). Structural basis and specificity of acyl-homoserine lactone signal production in bacterial quorum sensing. Mol Cell, 9, 685-694. PubMed id: 11931774 DOI: 10.1016/S1097-2765(02)00480-X

Date:

08-Oct-01 Release date: 17-Apr-02

Protein chain

P54656  (ESAI_PANSE) -  Acyl-homoserine-lactone synthase from Pantoea stewartii subsp. stewartii

Seq: 210 a.a.

Struc: 193 a.a.

Enzyme reactions

• Enzyme class: E.C.2.3.1.184 - acyl-homoserine-lactone synthase.
• Reaction: a fatty acyl-[ACP] + S-adenosyl-L-methionine = an N-acyl-L-homoserine lactone + S-methyl-5'-thioadenosine + holo-[ACP] + H⁺

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

reference

DOI no: 10.1016/S1097-2765(02)00480-X

Mol Cell 9:685-694 (2002)

PubMed id: 11931774

Structural basis and specificity of acyl-homoserine lactone signal production in bacterial quorum sensing.

W.T.Watson, T.D.Minogue, D.L.Val, S.B.von Bodman, M.E.Churchill.

ABSTRACT

Synthesis and detection of acyl-homoserine lactones (AHLs) enables many gram-negative bacteria to engage in quorum sensing, an intercellular signaling mechanism that activates differentiation to virulent and biofilm lifestyles. The AHL synthases catalyze acylation of S-adenosyl-L-methionine by acyl-acyl carrier protein and lactonization of the methionine moiety to give AHLs. The crystal structure of the AHL synthase, EsaI, determined at 1.8 A resolution, reveals a remarkable structural similarity to the N-acetyltransferases and defines a common phosphopantetheine binding fold as the catalytic core. Critical residues responsible for catalysis and acyl chain specificity have been identified from a modeled substrate complex and verified through functional analysis in vivo. A mechanism for the N-acylation of S-adenosyl-L-methionine by 3-oxo-hexanoyl-acyl carrier protein is proposed.

Selected figure(s)

Figure 2.
Figure 2. Sequence and Structural Alignment of Selected AHL Synthases and GNATsThe sequence and topology of the AHL synthase family is compared to the GCN5-related N-acetyltransferases. The gray shaded regions are conserved sequence blocks within each family that constitute the enzyme's “sequence signature.” Residues are colored red to indicate acidic or hydrophilic, blue for basic, and orange for other. Shaded residues are absolutely conserved, and the boxed residues are homologous within each family. Residues that comprise the core “phosphopantetheine binding fold” were identified by LSQMAN using a 2.0 Å cutoff and are indicated by black bars above the segments. The Tetrahymena GCN5 residues that contact the pantetheine or acetyl portion of the acetyl-CoA are indicated by “p” or “a,” respectively.

Figure 4.
Figure 4. Proposed Mechanism of Acyl Transfer(A) The stereodiagram of acyl-phosphopantetheine modeled into the EsaI active-site cavity viewed as in Figure 2A. The electrostatic surface, generated using GRASP (Nicholls et al., 1993) and Photoshop (Adobe), is colored red, white, and blue to indicate negatively charged, neutral, or positively charged regions of the surface, respectively. The individual atoms in the modeled phosphopantetheine are colored according to atom type.(B) The acylation cleft of EsaI and relevant residues are shown in gray, the modeled phosphopanteteine is shown in cyan, and the well-ordered water molecules observed in the native structure that lie along β4 are shown as red spheres.(C) The proposed N-acylation reaction is catalyzed via nucleophilic attack on the 1-carbonyl of acyl-ACP by the free amine electrons of SAM after proton abstraction by a water molecule stabilized by Glu97 or Ser99.

The above figures are reprinted by permission from Cell Press: Mol Cell (2002, 9, 685-694) copyright 2002.