Crystal structure of the alginate (Poly α-L-guluronate) lyase from Corynebacterium sp. at 1.2 Å resolution

The crystal structure of alginate (poly α-l-guluronate) lyase from Corynebacterium sp. (ALY-1) was determined at 1.2 Å resolution using the MAD method and bromide ions. The structure of ALY-1 is abundant in β-strands and has a deep cleft, similar to the jellyroll β-sandwich found in 1,3-1,4-β-glucanase. The structure suggests that alginate molecules may penetrate into the cleft to interact with the catalytic site of ALY-1. The reported crystal structure of another type of alginate lyase, A1-III, differs from that of ALY-1 in that it consists almost entirely of α-helical structure. Nevertheless, the putative catalytic residues in both enzymes are positioned in space in nearly identical arrangements. This finding suggests that both alginate lyases may have evolved through convergent evolution.