Chitin and peptidoglycan deacetylases: structures, specificities and engineering for biotech applications

S7.2 Bacterial cell-wall modification
Location (hall): 
Start/end time: 
Wednesday, July 3, 2019 - 11:15 to 11:45
Speaker reference: 

Antoni Planas1

1Universidad Ramon Llull, Barcelona, Spain

Pathogenic bacteria and fungi deacetylate their own cell wall polysaccharides as a strategy to evade the host immune responses at initial stages of infection. Pathogenic bacteria utilize acetylation (6-O-acetylation of MurNAc) and deacetylation (2-N-deacetylation of GlcNAc and/or MurNAc residues) of their cell wall peptidoglycan (PGN) to evade detection by the innate immune system. Likewise, plant pathogenic fungi partially deacetylate their cell wall chitin to be resistant to degradation by plant chitinases or deacetylate the released chitooligosaccahides (COS) to escape recognition by chitin receptors and evade the plant immune responses.

Peptidogycan and chitin deacetylases are members of family 4 carbohydrate esterases (CE4 enzymes) which operate by a metal-assisted general acid/base catalytic mechanism [1]. We are interested in understanding the structural bases of substrate specificity by CE4 enzymes, their mechanism of action and biological functions, as well as the use of engineered variants as biocatalysts. 

In this lecture, recent advances towards understanding and engineering substrate specificity of chitin and peptidoglycan deacetylases (CDAs and PGN DAs) will be presented:

  • Structural determinants of substrate specificity in CDAs: the subsite capping model to engineer specificity by rational and combinatorial approaches [1-4].
  • Peptidoglycan GlcNAc and MurNAc deacetylation specificities. Structure and properties of a novel MurNAc DA with dual specificity [5-6].
  • CE4 enzymes active of chitooligosaccharides as biocatalysts for the production of paCOS with defined and novel deacetylation patterns, current targets for a number of biotech applications. [3,7]
  1. Andrés E. et al. Angew. Chem. Int. Ed.. 2014, 53, 6882-7;
  2. Aranda-Martinez A. et al. Sci. Rep. 2018, 8, 2170;
  3. Grifoll-Romero L. et al. Polymers 2018, 10, 352;
  4. Pascual, S. and Planas, A. Anal.Chem. 2018, 90, 10654–10658;
  5. Aragunde H. et al. Int. J. Mol. Sci. 2018, 19, 412;
  6. Grifoll-Romero et al. Structure-function relationships underlying the dual N-acetylmuramic and N-acetylglucosamine specificities of the peptidoglycan deacetylase PdaC from Bacillus subtilis. Submitted;
  7. Hamer SN. et al. Sci. Rep. 2015, 5, article 8716.