Glycosyl hydrolases family 18.

Glyco_18 domain.

The Bacteroides thetaiotaomicron protein represented by pdb structure 3CO4 is an uncharacterized bacterial member of the family 18 glycosyl hydrolases with homologs found in Flavobacterium, Stigmatella, and Pseudomonas.

The GH18 (glycosyl hydrolases, family 18) type II chitinases hydrolyze chitin, an abundant polymer of N-acetylglucosamine and have been identified in bacteria, fungi, insects, plants, viruses, and protozoan parasites. The structure of this domain is an eight-stranded alpha/beta barrel with a pronounced active-site cleft at the C-terminal end of the beta-barrel.

This conserved domain family includes a large number of catalytically inactive chitinase-like lectins (chitolectins) including YKL-39, YKL-40 (HCGP39), YM1, oviductin, and AMCase (acidic mammalian chitinase), as well as catalytically active chitotriosidases. The conserved domain is an eight-stranded alpha/beta barrel fold belonging to the family 18 glycosyl hydrolases. The fold has a pronounced active-site cleft at the C-terminal end of the beta-barrel. The chitolectins lack a key active site glutamate (the proton donor required for hydrolytic activity) but retain highly conserved residues involved in oligosaccharide binding. Chitotriosidase is a chitinolytic enzyme expressed in maturing macrophages, which suggests that it plays a part in antimicrobial defense. Chitotriosidase hydrolyzes chitotriose, as well as colloidal chitin to yield chitobiose and is therefore considered an exochitinase. Chitotriosidase occurs in two major forms, the large form being converted to the small form by either RNA or post-translational processing. Although the small form, containing the chitinase domain alone, is sufficient for the chitinolytic activity, the additional C-terminal chitin-binding domain of the large form plays a role in processing colloidal chitin. The chitotriosidase gene is nonessential in humans, as about 35% of the population are heterozygous and 6% homozygous for an inactivated form of the gene. HCGP39 is a 39-kDa human cartilage glycoprotein thought to play a role in connective tissue remodeling and defense against pathogens.

Crystalstructure of the GH18 chitinase ChiB from the chitin utilization locus of Flavobacterium johnsoniae [Flavobacterium johnsoniae UW101]

Crystalstructure of a chitinase from Bacteroides thetaiotaomicron [Bacteroides thetaiotaomicron VPI-5482],3FND_A Crystal structure of a chitinase from Bacteroides thetaiotaomicron [Bacteroides thetaiotaomicron]

Specificityand affinity of natural product cyclopentapeptide inhibitors against Aspergillus fumigatus, human and bacterial chitinaseFra [Aspergillus fumigatus],1W9P_B Specificity and affinity of natural product cyclopentapeptide inhibitors against Aspergillus fumigatus, human and bacterial chitinaseFra [Aspergillus fumigatus],1W9U_A Specificity and affnity of natural product cyclopentapeptide inhibitor Argadin against Aspergillus fumigatus chitinase [Aspergillus fumigatus],1W9U_B Specificity and affnity of natural product cyclopentapeptide inhibitor Argadin against Aspergillus fumigatus chitinase [Aspergillus fumigatus],1W9V_A Specificity and affinity of natural product cyclopentapeptide argifin against Aspergillus fumigatus [Aspergillus fumigatus],1W9V_B Specificity and affinity of natural product cyclopentapeptide argifin against Aspergillus fumigatus [Aspergillus fumigatus],2A3A_A Crystal structure of Aspergillus fumigatus chitinase B1 in complex with theophylline [Aspergillus fumigatus],2A3A_B Crystal structure of Aspergillus fumigatus chitinase B1 in complex with theophylline [Aspergillus fumigatus],2A3B_A Crystal structure of Aspergillus fumigatus chitinase B1 in complex with caffeine [Aspergillus fumigatus],2A3B_B Crystal structure of Aspergillus fumigatus chitinase B1 in complex with caffeine [Aspergillus fumigatus],2A3C_A Crystal structure of Aspergillus fumigatus chitinase B1 in complex with pentoxifylline [Aspergillus fumigatus],2A3C_B Crystal structure of Aspergillus fumigatus chitinase B1 in complex with pentoxifylline [Aspergillus fumigatus],2A3E_A Crystal structure of Aspergillus fumigatus chitinase B1 in complex with allosamidin [Aspergillus fumigatus],2A3E_B Crystal structure of Aspergillus fumigatus chitinase B1 in complex with allosamidin [Aspergillus fumigatus],2IUZ_A Crystal structure of Aspergillus fumigatus chitinase B1 in complex with C2-dicaffeine [Aspergillus fumigatus],2IUZ_B Crystal structure of Aspergillus fumigatus chitinase B1 in complex with C2-dicaffeine [Aspergillus fumigatus],3CH9_A Crystal structure of Aspergillus fumigatus chitinase B1 in complex with dimethylguanylurea [Aspergillus fumigatus],3CH9_B Crystal structure of Aspergillus fumigatus chitinase B1 in complex with dimethylguanylurea [Aspergillus fumigatus],3CHC_A Crystal structure of Aspergillus fumigatus chitinase B1 in complex with monopeptide [Aspergillus fumigatus],3CHC_B Crystal structure of Aspergillus fumigatus chitinase B1 in complex with monopeptide [Aspergillus fumigatus],3CHD_A Crystal structure of Aspergillus fumigatus chitinase B1 in complex with dipeptide [Aspergillus fumigatus],3CHD_B Crystal structure of Aspergillus fumigatus chitinase B1 in complex with dipeptide [Aspergillus fumigatus],3CHE_A Crystal structure of Aspergillus fumigatus chitinase B1 in complex with tripeptide [Aspergillus fumigatus],3CHE_B Crystal structure of Aspergillus fumigatus chitinase B1 in complex with tripeptide [Aspergillus fumigatus],3CHF_A Crystal structure of Aspergillus fumigatus chitinase B1 in complex with tetrapeptide [Aspergillus fumigatus],3CHF_B Crystal structure of Aspergillus fumigatus chitinase B1 in complex with tetrapeptide [Aspergillus fumigatus]

Structureof human chitotriosidase [Homo sapiens]

Crystalstructure of a native chitinase from Aspergillus fumigatus YJ-407 [Aspergillus fumigatus],1WNO_B Crystal structure of a native chitinase from Aspergillus fumigatus YJ-407 [Aspergillus fumigatus]

Endochitinase OS=Brugia malayi OX=6279 PE=1 SV=1

Endochitinase B1 OS=Neosartorya fumigata OX=746128 GN=chiB1 PE=1 SV=1

Endochitinase B1 OS=Neosartorya fumigata (strain ATCC MYA-4609 / Af293 / CBS 101355 / FGSC A1100) OX=330879 GN=chiB1 PE=3 SV=1

Chitotriosidase-1 OS=Homo sapiens OX=9606 GN=CHIT1 PE=1 SV=1

Endochitinase B OS=Emericella nidulans (strain FGSC A4 / ATCC 38163 / CBS 112.46 / NRRL 194 / M139) OX=227321 GN=chiB PE=1 SV=1