Alignment of predicted Smp131 lysin with family 19 chitinases that have determined catalytic domains. Identical residues are highlighted, with the conserved glutamate residues involved in catalysis indicated by downward arrowheads. The conserved sequence motif, [FHY]-G-R-G-[AP]-X-Q-[IL]-[ST]-[FHYW]-[HN]-[FY]-NY, that forms the substrate binding region is boxed. Abbreviations: Smp131, lysin encoded by orf15 of Smp131; K279a, lysin encoded by prophage in S. maltophilia K279a (GenBank:YP_001970233); Xcc, lysin encoded by prophage in X. campestris pv. campestris ATCC33913 (GenBank:NP_638326); ChiC, chitinase C encoded by Streptomyces griseus (GenBank:YP_001824912); ChiG, chitinase G encoded by S. coelicolor (GenBank:BAA75648).