6BT4

Crystal structure of the SLH domain of Sap from Bacillus anthracis in complex with a pyruvylated SCWP unit

Summary for 6BT4

• Entry DOI: 10.2210/pdb6bt4/pdb
• Descriptor: S-layer protein sap, 2-(acetylamino)-4-O-{2-(acetylamino)-4,6-O-[(1S)-1-carboxyethylidene]-2-deoxy-beta-D-mannopyranosyl}-2-deoxy-beta-D-glucopyranose, SULFATE ION, ... (4 entities in total)
• Functional Keywords: s-layer homology domain, secondary cell wall polysaccharide, cell wall, anthrax, s-layer, structural protein
• Biological source: Bacillus anthracis
• Total number of polymer chains: 1
• Total formula weight: 22868.62

Authors

Sychantha, D.,Chapman, R.N.,Bamford, N.C.,Boons, G.J.,Howell, P.L.,Clarke, A.J. (deposition date: 2017-12-05, release date: 2018-03-21, Last modification date: 2023-10-04)

Primary citation

Sychantha, D.,Chapman, R.N.,Bamford, N.C.,Boons, G.J.,Howell, P.L.,Clarke, A.J.
Molecular Basis for the Attachment of S-Layer Proteins to the Cell Wall of Bacillus anthracis.
Biochemistry, 57:1949-1953, 2018

PubMed Abstract: Bacterial surface (S) layers are paracrystalline arrays of protein assembled on the bacterial cell wall that serve as protective barriers and scaffolds for housekeeping enzymes and virulence factors. The attachment of S-layer proteins to the cell walls of the Bacillus cereus sensu lato, which includes the pathogen Bacillus anthracis, occurs through noncovalent interactions between their S-layer homology domains and secondary cell wall polysaccharides. To promote these interactions, it is presumed that the terminal N-acetylmannosamine (ManNAc) residues of the secondary cell wall polysaccharides must be ketal-pyruvylated. For a few specific S-layer proteins, the O-acetylation of the penultimate N-acetylglucosamine (GlcNAc) is also required. Herein, we present the X-ray crystal structure of the SLH domain of the major surface array protein Sap from B. anthracis in complex with 4,6- O-ketal-pyruvyl-β-ManNAc-(1,4)-β-GlcNAc-(1,6)-α-GlcN. This structure reveals for the first time that the conserved terminal SCWP unit is the direct ligand for the SLH domain. Furthermore, we identify key binding interactions that account for the requirement of 4,6- O-ketal-pyruvyl-ManNAc while revealing the insignificance of the O-acetylation on the GlcNAc residue for recognition by Sap.

PubMed: 29522326
DOI: 10.1021/acs.biochem.8b00060

Experimental method

X-RAY DIFFRACTION (2.306 Å)