2W3Z

Structure of a Streptococcus mutans CE4 esterase

Summary for 2W3Z

• Entry DOI: 10.2210/pdb2w3z/pdb
• Descriptor: PUTATIVE DEACETYLASE, ZINC ION, PHOSPHATE ION, ... (4 entities in total)
• Functional Keywords: pgda, glcnac de-n-acetylase, hydrolase, divale metal cation dependent, carbohydrate esterase family 4, cell surface surface deacetylase
• Biological source: STREPTOCOCCUS MUTANS UA159
• Total number of polymer chains: 1
• Total formula weight: 35051.39

Authors

Deng, D.M.,Urch, J.E.,ten Cate, J.M.,Rao, V.A.,van Aalten, D.M.F.,Crielaard, W. (deposition date: 2008-11-17, release date: 2008-12-02, Last modification date: 2024-05-08)

Primary citation

Deng, D.M.,Urch, J.E.,Ten Cate, J.M.,Rao, V.A.,Van Aalten, D.M.F.,Crielaard, W.
Streptococcus Mutans Smu.623C Codes for a Functional, Metal Dependent Polysaccharide Deacetylase that Modulates Interactions with Salivary Agglutinin.
J.Bacteriol., 191:394-, 2009

PubMed Abstract: The genome sequence of the oral pathogen Streptococcus mutans predicts the presence of two putative polysaccharide deacetylases. The first, designated PgdA in this paper, shows homology to the catalytic domains of peptidoglycan deacetylases from Streptococcus pneumoniae and Listeria monocytogenes, which are both thought to be involved in the bacterial defense mechanism against human mucosal lysozyme and are part of the CAZY family 4 carbohydrate esterases. S. mutans cells in which the pgdA gene was deleted displayed a different colony texture and a slightly increased cell surface hydrophobicity and yet did not become hypersensitive to lysozyme as shown previously for S. pneumoniae. To understand this apparent lack of activity, the high-resolution X-ray structure of S. mutans PgdA was determined; it showed the typical carbohydrate esterase 4 fold, with metal bound in a His-His-Asp triad. Analysis of the protein surface showed that an extended groove lined with aromatic residues is orientated toward the active-site residues. The protein exhibited metal-dependent de-N-acetylase activity toward a hexamer of N-acetylglucosamine. No activity was observed toward shorter chitooligosaccharides or a synthetic peptidoglycan tetrasaccharide. In agreement with the lysozyme data this would suggest that S. mutans PgdA does not act on peptidoglycan but on an as-yet-unidentified polysaccharide within the bacterial cell surface. Strikingly, the pgdA-knockout strain showed a significant increase in aggregation/agglutination by salivary agglutinin, in agreement with this gene acting as a deacetylase of a cell surface glycan.

PubMed: 18978064
DOI: 10.1128/JB.00838-08

Experimental method

X-RAY DIFFRACTION (1.45 Å)