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Chitin

About: Chitin is a research topic. Over the lifetime, 6590 publications have been published within this topic receiving 253993 citations.


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Journal ArticleDOI
TL;DR: Results indicate that ChiA is a soluble extracellular chit inase required for chitin utilization and that it relies on a novel CTD for secretion by the F. johnsoniae T9SS.
Abstract: Flavobacterium johnsoniae, a member of phylum Bacteriodetes, is a gliding bacterium that digests insoluble chitin and many other polysaccharides. A novel protein secretion system, the type IX secretion system (T9SS), is required for gliding motility and for chitin utilization. Five potential chitinases were identified by genome analysis. Fjoh_4555 (ChiA), a 168.9-kDa protein with two glycoside hydrolase family 18 (GH18) domains, was targeted for analysis. Disruption of chiA by insertional mutagenesis resulted in cells that failed to digest chitin, and complementation with wild-type chiA on a plasmid restored chitin utilization. Antiserum raised against recombinant ChiA was used to detect the protein and to characterize its secretion by F. johnsoniae. ChiA was secreted in soluble form by wild-type cells but remained cell associated in strains carrying mutations in any of the T9SS genes, gldK, gldL, gldM, gldNO, sprA, sprE, and sprT. Western blot and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses suggested that ChiA was proteolytically processed into two GH18 domain-containing proteins. Proteins secreted by T9SSs typically have conserved carboxy-terminal domains (CTDs) belonging to the TIGRFAM families TIGR04131 and TIGR04183. ChiA does not exhibit strong similarity to these sequences and instead has a novel CTD. Deletion of this CTD resulted in accumulation of ChiA inside cells. Fusion of the ChiA CTD to recombinant mCherry resulted in secretion of mCherry into the medium. The results indicate that ChiA is a soluble extracellular chitinase required for chitin utilization and that it relies on a novel CTD for secretion by the F. johnsoniae T9SS.

85 citations

Journal ArticleDOI
TL;DR: The gene bank sequence data show that cod is highly conserved in Vibrios and Photobacteria, and encodes a deacetylase isolated from V. cholerae that is very active with chitin oligosaccharides, is virtually inactive with GlcNAc, and slightly active with colloidal ([(3)H]-N-acetyl)-chitin.
Abstract: Chitin, one of the most abundant organic substances in nature, is consumed by marine bacteria, such as Vibrio cholerae, via a multitude of tightly regulated genes (Li and Roseman 2004, Proc Natl Acad Sci USA. 101:627-631). One such gene, cod, is reported here. It encodes a chitin oligosaccharide deacetylase (COD), when cells are induced by chitobiose, (GlcNH(2))(2), or crude crab shells. COD was molecularly cloned (COD-6His), overproduced, and purified to apparent homogeneity. COD is secreted at all stages of growth by induced V. cholerae. The gene sequence predicts a 26 N-terminal amino acid signal peptide not found in the isolated protein. COD is very active with chitin oligosaccharides, is virtually inactive with GlcNAc, and slightly active with colloidal ([(3)H]-N-acetyl)-chitin. The oligosaccharides are converted almost quantitatively to products lacking one acetyl group. The latter were characterized by mass spectrometry (ESI-MS), and treatment with nitrous acid. COD catalyzes the following reactions (n = 2-6): (GlcNAc)(n)--> GlcNAc-GlcNH(2)-(GlcNAc)(n-2) + Ac(-). That is, COD hydrolyzes the N-acetyl groups attached to the penultimate GlcNAc residue. The gene bank sequence data show that cod is highly conserved in Vibrios and Photobacteria. One such gene encodes a deacetylase isolated from V. alginolytics (Ohishi et al. 1997, Biosci Biotech Biochem. 61:1113-1117; Ohishi et al. 2000, J Biosci Bioeng. 90:561-563), that is specific for (GlcNAc)(2), but inactive with higher oligosaccharides. The COD enzymatic products, GlcNAc-GlcNH(2)-(GlcNAc)(n), closely resemble those obtained by hydrolysis of the chitooligosaccharides with Nod B: GlcNH(2)-(GlcNAc)(3-4). The latter are key intermediates in the biosynthesis of Nod factors, critically important in communications between the symbiotic nitrogen fixing bacteria and plants. Conceivably, the COD products play equally important roles in cellular communications that remain to be defined.

85 citations

Journal ArticleDOI
TL;DR: Findings indicate that GlcNAc-GlcN is produced from chitin by the cooperative hydrolytic reactions of both Pa-Chi and Pa-COD.
Abstract: A chitin-degrading bacterial strain, KN1699, isolated from Yatsu dry beach (Narashino, Chiba Prefecture, Japan), was identified as Vibrio parahaemolyticus. Treatment of powdered chitin with crude enzyme solution prepared from the supernatant of KN1699 cultures yielded a disaccharide, β-d-N-acetylglucosaminyl-(1,4)-d-glucosamine (GlcNAc-GlcN), as the primary chitin degradation product. The extracellular enzymes involved in the production of this heterodisaccharide, chitinase (Pa-Chi; molecular mass, 92 kDa) and chitin oligosaccharide deacetylase (Pa-COD; molecular mass, 46 kDa), were isolated from the crude enzyme solution, and their hydrolysis specificities were elucidated. These studies confirmed that (1) Pa-Chi hydrolyzes chitin to produce (GlcNAc)2 and (2) Pa-COD hydrolyzes the acetamide group of reducing end GlcNAc residue of (GlcNAc)2. These findings indicate that GlcNAc-GlcN is produced from chitin by the cooperative hydrolytic reactions of both Pa-Chi and Pa-COD.

85 citations

Journal ArticleDOI
TL;DR: Chitin was more suitable for applications to fruit juice liquefaction because both immobilized pectinlyase and endocellulase showed higher activity at low pH and low temperature.

85 citations

Journal ArticleDOI
25 Oct 1974-Science
TL;DR: A "soluble" form of chitin synthetase was separated from a membrane-rich fraction by exposure to the enzyme substrate (uridine diphosphate N-acetyl-D-glucosamine) and activator (Nacetyl, D-glocosamine), which catalyzed the synthesis of microfibrils similar, if not identical, to those formed by the fungus as discussed by the authors.
Abstract: A "soluble" form of chitin synthetase was separated from a membrane-rich fraction by exposure to the enzyme substrate (uridine diphosphate N-acetyl-D-glucosamine) and activator (N-acetyl- D-glucosamine). The solubilized enzyme catalyzed the synthesis of chitin microfibrils similar, if not identical, to those formed in vivo by the fungus. Cell wall microfibrils were thus abundantly formed in the absence of a living cell or its membranes.

85 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023434
2022868
2021271
2020354
2019333
2018271