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Crystal structure of a lyase from Alteromonas sp.
Structural highlights
FunctionUL24S_ALTSL Ulvan lyase involved in ulvan degradation. Ulvan is the main polysaccharide component of the Ulvales (green seaweed) cell wall. It is composed of disaccharide building blocks comprising 3-sulfated rhamnose (Rha3S) linked to D-glucuronic acid (GlcA), L-iduronic acid (IduA), or D-xylose (Xyl). Ulvan lyase catalyzes preferentially the endolytic cleavage of the glycosidic bond between Rha3S and the uronic acid GlcA, but not IduA, producing oligosaccharides that have unsaturated 4-deoxy-L-threo-hex-4-enopyranosiduronic acid (deltaUA) at the non-reducing end. The most abundant end products in the degradation of the ulvan polysaccharide were deltaUA-Rha3S disaccharides and deltaUA-Rha3S-IduA-Rha3S and deltaUA-Rha3S-Xyl-Rha3S tetrasaccharides.[1] Publication Abstract from PubMedMarine macroalgae have gained considerable attention as renewable biomass sources. Ulvan is a water-soluble anionic polysaccharide, and its depolymerization into fermentable monosaccharides has great potential for the production of bioethanol or high-value food additives. Ulvan lyase from Alteromonas sp. (AsPL) utilizes a beta-elimination mechanism to cleave the glycosidic bond between rhamnose 3-sulfate and glucuronic acid, forming an unsaturated uronic acid at the non-reducing end. AsPL was active in the temperature range of 30-50 degrees C and pH values ranging from 7.5 to 9.5. Furthermore, AsPL was found to be halophilic, showing high activity and stability in the presence of up to 2.5M NaCl. The apparent Km and kcat values of AsPL are 3.19+/-0.37mgmL(-1) and 4.19+/-0.21s(-1), respectively. Crystal structure analysis revealed that AsPL adopts a beta-propeller fold with four anti-parallel beta-strands in each of the seven propeller blades. The acid residues at the protein surface and two Ca(2+) coordination sites contribute to its salt tolerance. The research on ulvan lyase has potential commercial value in the utilization of algal resources for biofuel production to relieve the environmental burden of petrochemicals. Biochemical characterization and structural analysis of ulvan lyase from marine Alteromonas sp. reveals the basis for its salt tolerance.,Qin HM, Gao D, Zhu M, Li C, Zhu Z, Wang H, Liu W, Tanokura M, Lu F Int J Biol Macromol. 2020 Mar 15;147:1309-1317. doi:, 10.1016/j.ijbiomac.2019.10.095. Epub 2019 Nov 18. PMID:31751708[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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