title: Chitosanase from Streptomyces coelicolor A3(2): biochemical properties and role in protection against antibacterial effect of chitosan.
abstract: Chitosan, an N-deacetylated derivative of chitin, has attracted much attention as an antimicrobial agent against fungi, bacteria, and viruses. Chitosanases, the glycoside hydrolases responsible for chitosan depolymerisation, are intensively studied as tools for biotechnological transformation of chitosan. The chitosanase CsnA (SCO0677) from Streptomyces coelicolor A3(2) was purified and characterized. CsnA belongs to the GH46 family of glycoside hydrolases. However, it is secreted efficiently by the Tat translocation pathway despite its similarity to the well-studied chitosanase from Streptomyces sp. N174 (CsnN174), which is preferentially secreted through the Sec pathway. Melting point determination, however, revealed substantial differences between these chitosanases, both in the absence and in the presence of chitosan. We further assessed the role of CsnA as a potential protective enzyme against the antimicrobial effect of chitosan. A Streptomyces lividans TK24 strain in which the csnA gene was inactivated by gene disruption was more sensitive to chitosan than the wild-type strain or a chitosanase-overproducing strain. This is the first genetic evidence for the involvement of chitosanases in the protection of bacteria against the antimicrobial effect of chitosan.
authors.affiliation: Centre d'Étude et de Valorisation de la Diversité Microbienne, Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
authors.forename: Mariana Gabriela
authors.initials: MG
authors.lastname: Ghinet
authors.forename: Sébastien
authors.initials: S
authors.lastname: Roy
authors.forename: Dominic
authors.initials: D
authors.lastname: Poulin-Laprade
authors.forename: Marie-Ève
authors.initials: MÈ
authors.lastname: Lacombe-Harvey
authors.forename: Rolf
authors.initials: R
authors.lastname: Morosoli
authors.forename: Ryszard
authors.initials: R
authors.lastname: Brzezinski
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000494:pharmacology / Q000502:physiology; D002686:Chitin / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D048271:Chitosan / Q000737:chemistry / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000494:pharmacology / Q000502:physiology; D008969:Molecular Sequence Data; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D048372:Streptomyces coelicolor / Q000201:enzymology* / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002686:Chitin; D048271:Chitosan; D006026:Glycoside Hydrolases; C019868:chitosanase