Trigalacturonate-producing pectate lyase PelQ1 from Saccharobesus litoralis with unique exolytic activity

Carbohydr Res. 2024 Jan 26;536:109045. doi: 10.1016/j.carres.2024.109045. Online ahead of print.ABSTRACTPelQ1 from Saccharobesus litoralis is a Ca2+-dependent pectate lyase belonging to the polysaccharide lyase family 1 (PL1). Although being an endolytic enzyme, it degraded polygalacturonate into predominantly unsaturated trimer in an exolytic manner with delayed production of dimer, tetramer and pentamer. The enzyme harbours a C-terminal domain from the carbohydrate-binding module family 13 (CBM13), whose presence facilitated the production of dimer. PelQ1's homology model showed that it possessed a well-conserved catalytic cleft, with R232 acting as the general base and R203 as the general acid. Structural comparison with DcPelC, a similar trimer-generating pectate lyase from Dickeya chrysanthemi EC16, implied that both enzymes' catalytic clefts encompassed at least eight subsites, i.e. -5 to +3. The unequal distribution of the subsites between the reducing and non-reducing ends of the cleavage site might be responsible for the exolytic generation of the trimer. As all but the -1, +1 and + 2 subsites could accommodate methylated galacturonate, this subclass of PL1 pectate lyases may function to help break up methylated pectin.PMID:38340525 | DOI:10.1016/j.carres.2024.109045
Source: Carbohydrate Research - Category: Genetics & Stem Cells Authors: Source Type: research
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