title: Characterization of a New Cold-Adapted and Salt-Activated Polysaccharide Lyase Family 7 Alginate Lyase from Pseudoalteromonas sp. SM0524.
abstract: Marine bacterial alginate lyases play a role in marine alginate degradation and carbon cycling. Although a large number of alginate lyases have been characterized, reports on alginate lyases with special characteristics are still rather less. Here, a gene alyPM encoding an alginate lyase of polysaccharide lyase family 7 (PL7) was cloned from marine Pseudoalteromonas sp. SM0524 and expressed in Escherichia coli. AlyPM shows 41% sequence identity to characterized alginate lyases, indicating that AlyPM is a new PL7 enzyme. The optimal pH for AlyPM activity was 8.5. AlyPM showed the highest activity at 30°C and remained 19% of the highest activity at 5°C. AlyPM was unstable at temperatures above 30°C and had a low T m of 37°C. These data indicate that AlyPM is a cold-adapted enzyme. Moreover, AlyPM is a salt-activated enzyme. AlyPM activity in 0.5-1.2 M NaCl was sixfolds higher than that in 0 M NaCl, probably caused by a significant increase in substrate affinity, because the K m of AlyPM in 0.5 M NaCl decreased more than 20-folds than that in 0 M NaCl. AlyPM preferably degraded polymannuronate and mainly released dimers and trimers. These data indicate that AlyPM is a new PL7 endo-alginate lyase with special characteristics.
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong UniversityJinan, China; Marine Biotechnology Research Center, Shandong UniversityJinan, China.
authors.forename: Xiu-Lan
authors.initials: XL
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong UniversityJinan, China; Marine Biotechnology Research Center, Shandong UniversityJinan, China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Dong
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong UniversityJinan, China; Marine Biotechnology Research Center, Shandong UniversityJinan, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong UniversityJinan, China; Marine Biotechnology Research Center, Shandong UniversityJinan, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Dong
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong UniversityJinan, China; Marine Biotechnology Research Center, Shandong UniversityJinan, China; Institute of Marine Science and Technology, Shandong UniversityJinan, China.
authors.forename: Ping-Yi
authors.initials: PY
authors.lastname: Li
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong UniversityJinan, China; Marine Biotechnology Research Center, Shandong UniversityJinan, China.
authors.forename: Xi-Ying
authors.initials: XY
authors.lastname: Zhang
authors.affiliation: Marine Biotechnology Research Center, Shandong University Jinan, China.
authors.forename: Bai-Cheng
authors.initials: BC
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong UniversityJinan, China; Marine Biotechnology Research Center, Shandong UniversityJinan, China; Institute of Marine Science and Technology, Shandong UniversityJinan, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and TechnologyQingdao, China.
authors.forename: Yu-Zhong
authors.initials: YZ
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong UniversityJinan, China; Marine Biotechnology Research Center, Shandong UniversityJinan, China.
authors.forename: Bin-Bin
authors.initials: BB
authors.lastname: Xie
keywords: alginate lyase; cold-adapted enzyme; marine bacteria; polysaccharide lyase family 7; salt-activated