Cleaves the glycosidic bonds of gellan backbone and releases tetrasaccharide units of glucuronyl-glucosyl-rhamnosyl-glucose with unsaturated glucuronic acid at the non-reducing terminal. The enzyme is highly specific to the heteropolysaccharide gellan, especially deacetylated gellan. Eliminative cleavage of beta-D-glucopyranosyl-(1->4)-beta-D-glucopyranosyluronate bonds of gellan backbone releasing tetrasaccharides containing a 4-deoxy-4,5-unsaturated D-glucopyranosyluronic acid at the non-reducing end. The tetrasaccharide produced from deacetylated gellan is beta-D-4-deoxy-Delta(4)-GlcAp-(1->4)-beta-D-Glcp-(1->4)-alpha-L-Rhap-(1->3)-beta-D-Glcp. Optimum pH is 6.0 in potassium phosphate and 7.5 in HEPES buffer. Subject to proteolytic processing after secretion. Cleavage occurs between Gly-1205 and Leu-1206. This gives rise to a N-terminal gellan lyase of 130 kDa being the mature form of the gellan lyase. The function of C-terminal gellan lyase is not known.