PDBsum entry 2wlc

Transferase

PDB id: 2wlc

Contents

Protein chain

211 a.a. *

Ligands

ACT ×3

EDO ×5

PO4 ×5

Waters ×214

* Residue conservation analysis

PDB id:

2wlc

Name:

Transferase

Title:

Crystallographic analysis of the polysialic acid o-acetyltransferase oatwy

Structure:

Polysialic acid o-acetyltransferase. Chain: a. Engineered: yes. Mutation: yes. Other_details: left-handed beta helix

Source:

Neisseria meningitidis serogroup y. Organism_taxid: 648194. Strain: 406y. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

1.95Å R-factor: 0.174 R-free: 0.209

Authors:

H.J.Lee,B.Rakic,M.Gilbert,W.W.Wakarchuk,S.G.Withers,N.C.J.Strynadka

Key ref:

H.J.Lee et al. (2009). Structural and kinetic characterizations of the polysialic acid O-acetyltransferase OatWY from Neisseria meningitidis. J Biol Chem, 284, 24501-24511. PubMed id: 19525232 DOI: 10.1074/jbc.M109.006049

Date:

23-Jun-09 Release date: 30-Jun-09

Protein chain

Q93S40  (OATWY_NEIME) -  Polysialic acid O-acetyltransferase from Neisseria meningitidis

Seq: 215 a.a.

Struc: 211 a.a.*

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

Enzyme reactions

• Enzyme class: E.C.2.3.1.- - ?????

DOI no: 10.1074/jbc.M109.006049

J Biol Chem 284:24501-24511 (2009)

PubMed id: 19525232

Structural and kinetic characterizations of the polysialic acid O-acetyltransferase OatWY from Neisseria meningitidis.

H.J.Lee, B.Rakić, M.Gilbert, W.W.Wakarchuk, S.G.Withers, N.C.Strynadka.

ABSTRACT

The neuroinvasive pathogen Neisseria meningitidis has 13 capsular serogroups, but the majority of disease is caused by only 5 of these. Groups B, C, Y, and W-135 all display a polymeric sialic acid-containing capsule that provides a means for the bacteria to evade the immune response during infection by mimicking host sialic acid-containing cell surface structures. These capsules in serogroups C, Y, and W-135 can be further acetylated by a sialic acid-specific O-acetyltransferase, a modification that correlates with decreased immunoreactivity and increased virulence. In N. meningitidis serogroup Y, the O-acetylation reaction is catalyzed by the enzyme OatWY, which we show has clear specificity toward the serogroup Y capsule ([Glc-(alpha1-->4)-Sia](n)). To understand the underlying molecular basis of this process, we have performed crystallographic analysis of OatWY with bound substrate as well as determined kinetic parameters of the wild type enzyme and active site mutants. The structure of OatWY reveals an intimate homotrimer of left-handed beta-helix motifs that frame a deep active site cleft selective for the polysialic acid-bearing substrate. Within the active site, our structural, kinetic, and mutagenesis data support the role of two conserved residues in the catalytic mechanism (His-121 and Trp-145) and further highlight a significant movement of Tyr-171 that blocks the active site of the enzyme in its native form. Collectively, our results reveal the first structural features of a bacterial sialic acid O-acetyltransferase and provide significant new insight into its catalytic mechanism and specificity for the capsular polysaccharide of serogroup Y meningococci.

Selected figure(s)

Figure 1.
Reaction scheme of the OatWY-catalyzed O-acetyltransferase. Although acetylation of both the O-7 and O-9 hydroxyl group of the N. meningitidis serogroup Y polysialic acid has been implied through NMR analysis of the corresponding bacterial capsule (11), for simplicity only the O-9 transfer is shown here.

Figure 5.
Mechanistic scheme of OatWY polysialic acid acetyltransferase. In the schematic above, the two interacting subunits, which define a complete active site, are represented as gray boxes and serve to illustrate the conformational role of Tyr-171 in allowing access to substrate acetyl-CoA. In the dotted box below, a proposed mechanistic scheme is shown highlighting the role of His-121 from one subunit and Trp-145′ from the second subunit that make up the active site.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2009, 284, 24501-24511) copyright 2009.

Figures were selected by an automated process.