Cortical fragment-lytic enzyme (CFLE) is a peptidoglycan hydrolase involved in bacterial endospore germination. CFLE is expressed as an inactive preprotein (called SleB) in the forespore compartment of sporulating cells. SleB translocates across the forespore inner membrane and is deposited as a mature enzyme in the cortex layer of the spore. As part of a sensory mechanism capable of initiating germination, CFLE degrades a spore-specific peptidoglycan constituent called muramic-acid delta-lactam that comprises the outer cortex. CFLE has a C-terminal glycosyl hydrolase family 18 (GH18) catalytic domain as well as two N-terminal LysM peptidoglycan-binding domains. In addition to SleB, this family includes YaaH, YdhD, and YvbX from Bacillus subtilis.

Spore germination protein YaaH [Cell cycle control, cell division, chromosome partitioning].

Glyco_18 domain.

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.

Glycosyl hydrolases family 18.

ChainA, Putative sporulation-specific glycosylase ydhD [Bacillus subtilis subsp. subtilis str. 168],3CZ8_B Chain B, Putative sporulation-specific glycosylase ydhD [Bacillus subtilis subsp. subtilis str. 168]

Thecrystal structure of a class V chitininase from Pseudomonas fluorescens Pf-5 [Pseudomonas protegens Pf-5]

Crystalstructure of chitinase from Chromobacterium violaceum ATCC 12472 [Chromobacterium violaceum ATCC 12472]

ChainA, Glycoside hydrolase family 18 [Desulfitobacterium hafniense DCB-2],4WIW_B Chain B, Glycoside hydrolase family 18 [Desulfitobacterium hafniense DCB-2],4WIW_C Chain C, Glycoside hydrolase family 18 [Desulfitobacterium hafniense DCB-2],4WIW_D Chain D, Glycoside hydrolase family 18 [Desulfitobacterium hafniense DCB-2],4WIW_E Chain E, Glycoside hydrolase family 18 [Desulfitobacterium hafniense DCB-2],4WIW_F Chain F, Glycoside hydrolase family 18 [Desulfitobacterium hafniense DCB-2]

Crystalstructure of the Bacillus cereus spore cortex-lytic enzyme SleL [Bacillus cereus ATCC 10876],4S3J_B Crystal structure of the Bacillus cereus spore cortex-lytic enzyme SleL [Bacillus cereus ATCC 10876],4S3J_C Crystal structure of the Bacillus cereus spore cortex-lytic enzyme SleL [Bacillus cereus ATCC 10876]

Putative sporulation-specific glycosylase YdhD OS=Bacillus subtilis (strain 168) OX=224308 GN=ydhD PE=1 SV=2

Uncharacterized glycosylase YvbX OS=Bacillus subtilis (strain 168) OX=224308 GN=yvbX PE=3 SV=1

Putative glycosylase YkvQ OS=Bacillus subtilis (strain 168) OX=224308 GN=ykvQ PE=3 SV=1

Cortical fragment-lytic enzyme OS=Bacillus subtilis (strain 168) OX=224308 GN=sleL PE=1 SV=2

Cortical fragment-lytic enzyme OS=Bacillus anthracis OX=1392 GN=sleL PE=2 SV=1