Abstract
Chitin deacetylases, occurring in marine bacteria, several fungi and a few insects, catalyze the deacetylation of chitin, a structural biopolymer found in countless forms of marine life, fungal cell and spore walls as well as insect cuticle and peritrophic matrices. The deacetylases recognize a sequence of four GlcNAc units in the substrate, one of which undergoes deacetylation: the resulting chitosan has a more regular deacetylation pattern than a chitosan treated with hot NaOH. Nevertheless plain chitin is a poor substrate, but glycolated, reprecipitated or depolymerized chitins are good ones. The marine Vibrio sp. colonize the chitin particles and decompose the chitin thanks to the concerted action of chitinases and deacetylases, otherwise they could not tolerate chitosan, a recognized antibacterial biopolymer. In fact, chitosan is used to prevent infections in fishes and crustaceans. Considering that chitin deacetylases play very important roles in the biological attack and defense systems, they may find applications for the biological control of fungal plant pathogens or insect pests in agriculture and for the biocontrol of opportunistic fungal human pathogens.
Highlights
The enzyme chitin deacetylase (EC 3.5.1.41) hydrolyzes the acetamido group in theN-acetylglucosamine units of chitin and chitosan, generating glucosamine units and acetic acid
Chitin deacetylase was first discovered from extracts of the fungus Mucor rouxii [5] and it was further found that the enzyme was associated with cell wall synthesis by converting nascent chitin into chitosan [6]
Most of the reported insect chitin deacetylases are associated with the midgut peritrophic membrane (PM) and evenly distributed throughout the entire length of PM, as shown for the chitin deacetylases from T. ni [26], H. armigera
Summary
N-acetylglucosamine units of chitin and chitosan, generating glucosamine units and acetic acid. It is one of the members of the carbohydrate esterase family 4 (CE-4s), as defined in the CAZY database (http://afmb.cnrs-mrs.fr/~cazy/CAZY) [1]. Colletotrichum lindemuthianum chitin deacetylase has been the most well studied, including its biochemical properties [12,22], catalytic mechanism [23,24] and biological roles [25]. Fungal chitin deacetylases have been studied more amply than those from insects and from marine bacteria. In this review we describe the occurrences of chitin deacetylases in marine invertebrates, in marine and terrestrial fungi, in insects and marine bacteria, along with their biochemical properties, modes of action, biological roles and applications
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