AUTHOR=Chen Xiu-Lan , Dong Sheng , Xu Fei , Dong Fang , Li Ping-Yi , Zhang Xi-Ying , Zhou Bai-Cheng , Zhang Yu-Zhong , Xie Bin-Bin 

TITLE=Characterization of a New Cold-Adapted and Salt-Activated Polysaccharide Lyase Family 7 Alginate Lyase from Pseudoalteromonas sp. SM0524

JOURNAL=Frontiers in Microbiology

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2016.01120

DOI=10.3389/fmicb.2016.01120

ISSN=1664-302X

ABSTRACT=<p>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 <italic>alyPM</italic> encoding an alginate lyase of polysaccharide lyase family 7 (PL7) was cloned from marine <italic>Pseudoalteromonas</italic> sp. SM0524 and expressed in <italic>Escherichia coli.</italic> 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 <italic>T</italic><sub>m</sub> 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 <italic>K</italic><sub>m</sub> 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.</p>