Cloning Expression and Characterization of a New PL25 Family Ulvan Lyase from Marine Bacterium Alteromonas sp. A321

摘要

Ulvan lyases can degrade ulvan to oligosaccharides with potent biological activity. A new ulvan lyase gene, , was identified in sp. A321. Soluble expression of was achieved in BL21 (DE3). The 1314-bp gene encoded a protein with 437 amino acid residues. The amino acid sequence of ALT3695 exhibited low sequence identity with polysaccharide lyase family 25 (PL25) ulvan lyases from sp. PLSV (64.14% identity), sp. LOR (62.68% identity), and PLR (57.37% identity). Recombinant ALT3695 was purified and the apparent molecular weight was about 53 kDa, which is different from that of other polysaccharide-degrading enzymes identified in sp. A321. ALT3695 exhibited maximal activity in 50 mM Tris-HCl buffer at pH 8.0 and 50 °C. ALT3695 was relatively thermostable, as 90% activity was observed after incubation at 40 °C for 3 h. The and values of ALT3695 towards ulvan were 0.43 mg·mL and 0.11 μmol·min ·mL , respectively. ESI-MS analysis showed that were mainly disaccharides and tetrasaccharides. This study reports a new PL25 family ulvan lyase, ALT3695, with properties that suggest its great potential for the preparation of ulvan oligosaccharides.