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Members of polysaccharide lyase family 44 have been shown to exhibit alginate lyase activity. The first member of this family is Aly44A, which originates from the bacterium Bacillus sp. FJAT-50079. (Genbank number WP_213137828.1). A total of 126 homologous sequences of Aly44A were identified by utilizing the BLASTp (with sequence coverage > 70% and identity > 40%) and CD-Hit tools. Meanwhile, four homologs of Aly44A exhibited the ability to degrade alginate [1].
Kinetics and Mechanism
The kinetic analysis showed that Aly44A exhibited higher conversion efficiency and a stronger affinity for polyM compared to polyG, indicating Aly44A was polyM-preferred. In contrast to bifunctional alginate lyases, which exhibited no preference for polyG or polyM, Aly44A showed superior potential in the preparation of alginate oligosaccharides consisting of M-blocks. It showed that Aly44A had a higher affinity and catalytic efficiency towards the polyM region of the longer-chain alginate [1].
Action Pattern
Based on the analysis of the action pattern, it showed that Aly44A was polyM-preferred. Aly44A was verified to exhibit a random endo-acting lyase activity to alginate. The final products of degradation were alginate oligosaccharides with DP 2-8, the main products of degradation were AOS with DP 2-4 as detected by UPSEC-MS [1].
Catalytic Residues
No catalytic residues have been identified in this polysaccharide lyase family at present.
Three-dimensional structures
The structure of Aly44A was predicted to be a parallel β-helix by AlphaFold2 [1].
Family Firsts
First description of catalytic activity
The alginate lyase Aly44A was the first member of the family PL44 to be identified and characterized.
