C-terminal domain of rhamnogalacturonan lyase, a family 4 polysaccharide lyase
The rhamnogalacturonan lyase of the polysaccharide lyase family 4 (RGL4) is involved in the degradation of RG (rhamnogalacturonan) type-I, an important pectic plant cell wall polysaccharide, by cleaving the alpha-1,4 glycoside bond between L-rhamnose and D-galacturonic acids in the backbone of RG type-I through a beta-elimination reaction. RGL4 consists of three domains, an N-terminal catalytic domain, a middle domain with a FNIII type fold and a C-terminal domain with a jelly roll fold. Both the middle and the C-terminal domain are putative carbohydrate binding modules. There are two types of RG lyases, which both cleave the alpha-1,4 bonds of the RG-I main chain (RG chain) through the beta-elimination reaction, but belong to two structurally unrelated polysaccharide lyase (PL) families, 4 and 11.