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].

Lysin Motif is a small domain involved in binding peptidoglycan. LysM, a small globular domain with approximately 40 amino acids, is a widespread protein module involved in binding peptidoglycan in bacteria and chitin in eukaryotes. The domain was originally identified in enzymes that degrade bacterial cell walls, but proteins involved in many other biological functions also contain this domain. It has been reported that the LysM domain functions as a signal for specific plant-bacteria recognition in bacterial pathogenesis. Many of these enzymes are modular and are composed of catalytic units linked to one or several repeats of LysM domains. LysM domains are found in bacteria and eukaryotes.

Lysin motif.

The GH18 (glycosyl hydrolase, family 18) type II chitinases hydrolyze chitin, an abundant polymer of beta-1,4-linked N-acetylglucosamine (GlcNAc) which is a major component of the cell wall of fungi and the exoskeleton of arthropods. Chitinases have been identified in viruses, bacteria, fungi, protozoan parasites, insects, and plants. The structure of the GH18 domain is an eight-stranded beta/alpha barrel with a pronounced active-site cleft at the C-terminal end of the beta-barrel. The GH18 family includes chitotriosidase, chitobiase, hevamine, zymocin-alpha, narbonin, SI-CLP (stabilin-1 interacting chitinase-like protein), IDGF (imaginal disc growth factor), CFLE (cortical fragment-lytic enzyme) spore hydrolase, the type III and type V plant chitinases, the endo-beta-N-acetylglucosaminidases, and the chitolectins. The GH85 (glycosyl hydrolase, family 85) ENGases (endo-beta-N-acetylglucosaminidases) are closely related to the GH18 chitinases and are included in this alignment model.

ChainA, Spore germination protein YaaH [Priestia megaterium QM B1551]

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]

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]

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

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

Cortical fragment-lytic enzyme OS=Bacillus cereus OX=1396 GN=sleL PE=1 SV=1

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