PDBsum entry 2ixb

Hydrolase

PDB id: 2ixb

Contents

Protein chain

426 a.a. *

Ligands

NAD

A2G

MRD ×2

MPD

Waters ×178

* Residue conservation analysis

PDB id:

2ixb

Name:

Hydrolase

Title:

Crystal structure of n-acetylgalactosaminidase in complex with galnac

Structure:

Alpha-n-acetylgalactosaminidase. Chain: a. Engineered: yes

Source:

Flavobacterium meningosepticum. Organism_taxid: 238. Atcc: 13253. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008. Expression_system_variant: rosetta plyss.

Resolution:

2.40Å R-factor: 0.174 R-free: 0.200

Authors:

G.Sulzenbacher,Q.P.Liu,Y.Bourne,B.Henrissat,H.Clausen

Key ref:

Q.P.Liu et al. (2007). Bacterial glycosidases for the production of universal red blood cells. Nat Biotechnol, 25, 454-464. PubMed id: 17401360 DOI: 10.1038/nbt1298

Date:

07-Jul-06 Release date: 10-Apr-07

Protein chain

A4Q8F7  (GH109_ELIME) -  Alpha-N-acetylgalactosaminidase from Elizabethkingia meningoseptica

Seq: 444 a.a.

Struc: 426 a.a.

Enzyme reactions

• Enzyme class: E.C.3.2.1.49 - alpha-N-acetylgalactosaminidase.
• Reaction: Hydrolysis of terminal non-reducing N-acetyl-D-galactosamine residues in N-acetyl-alpha-D-galactosaminides.

DOI no: 10.1038/nbt1298

Nat Biotechnol 25:454-464 (2007)

PubMed id: 17401360

Bacterial glycosidases for the production of universal red blood cells.

Q.P.Liu, G.Sulzenbacher, H.Yuan, E.P.Bennett, G.Pietz, K.Saunders, J.Spence, E.Nudelman, S.B.Levery, T.White, J.M.Neveu, W.S.Lane, Y.Bourne, M.L.Olsson, B.Henrissat, H.Clausen.

ABSTRACT

Enzymatic removal of blood group ABO antigens to develop universal red blood cells (RBCs) was a pioneering vision originally proposed more than 25 years ago. Although the feasibility of this approach was demonstrated in clinical trials for group B RBCs, a major obstacle in translating this technology to clinical practice has been the lack of efficient glycosidase enzymes. Here we report two bacterial glycosidase gene families that provide enzymes capable of efficient removal of A and B antigens at neutral pH with low consumption of recombinant enzymes. The crystal structure of a member of the alpha-N-acetylgalactosaminidase family reveals an unusual catalytic mechanism involving NAD+. The enzymatic conversion processes we describe hold promise for achieving the goal of producing universal RBCs, which would improve the blood supply while enhancing the safety of clinical transfusions.

Selected figure(s)

Figure 1.
The immunodominant A and B trisaccharide epitopes are formed from the common H disaccharide substrate by 1,3-N-acetylgalactosaminyltransferase (GTA), defined by the blood group A gene, and -galactosyltransferase (GTB), defined by the blood group B gene, respectively. Conversely, the strategy used for enzymatic conversion of blood group A and B antigens to H involves exoglycosidases that specifically hydrolyze the 1,3GalNAc ( -N-acetylgalactosidase, A-zyme) or the 1,3galactose ( -galactosidase, B-zyme) to form the common H structure found on O RBCs. Black arrows indicate the different C-2 N-acetyl group of GalNAc and OH group of Gal in the immunodominant A and B epitopes, respectively. The immunodominant epitopes are positioned at the termini of oligosaccharide chains on glycolipids and glycoproteins as indicated by R. Increased complexity in ABH oligosaccharide structures are provided by the oligosaccharide carrier chain (R). On human RBCs most structures are based on type 2 polylactosamine chains with repeating Gal 1-4GlcNAc disaccharide units (both glycolipids and N-linked glycoproteins). A minor amount of type 1 chain ABH structures with Gal 1-3GlcNAc are found as glycolipids adsorbed from plasma^3.

Figure 2.
(a) Left panel. Cartoon representation of the overall structure of the -N-acetylgalactosaminidase dimer. In the left subunit, the dinucleotide binding domain (residues 19–148) is shown in pink, the -helices of the C-terminal domain (residues 149–444) in cyan, the -sheet forming the dimer interface in yellow, and the -helical bundle covering the NAD^+-binding tunnel in green. In the right subunit, a partial surface representation shows the entry of the NAD^+ binding tunnel and the active-site pocket. NAD^+ and GalNAc are shown as orange and red sticks, respectively. Right panel.

The above figures are reprinted by permission from Macmillan Publishers Ltd: Nat Biotechnol (2007, 25, 454-464) copyright 2007.

Figures were selected by an automated process.