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Mechanistic insights into substrate recognition and catalysis of a new ulvan lyase of polysaccharide lyase family 24

Citation

Xu, F and Dong, F and Sun, X-H and Cao, H-Y and Fu, H-H and Li, C-Y and Zhang, X-Y and McMinn, A and Zhang, Y-Z and Wang, P and Chen, X-L, Mechanistic insights into substrate recognition and catalysis of a new ulvan lyase of polysaccharide lyase family 24, Applied and Environmental Microbiology, 87, (12) Article e00412-21. ISSN 1098-5336 (2021) [Refereed Article]


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DOI: doi:10.1128/AEM.00412-21

Abstract

Ulvan is an important marine polysaccharide. Bacterial ulvan lyases play important roles in ulvan degradation and marine carbon cycling. Until now, only a small number of ulvan lyases have been characterized. Here, a new ulvan lyase, Uly1, belonging to polysaccharide lyase family 24 (PL24) from the marine bacterium Catenovulum maritimum, is characterized. The optimal temperature and pH for Uly1 to degrade ulvan are 40C and pH 9.0, respectively. Uly1 degrades ulvan polysaccharides in the endolytic manner, mainly producing ΔRha3S, consisting of an unsaturated 4-deoxy-l-threo-hex-4-enopyranosiduronic acid and a 3-O-sulfated α-l-rhamnose. The structure of Uly1 was resolved at a 2.10- resolution. Uly1 adopts a seven-bladed β-propeller architecture. Structural and site-directed mutagenesis analyses indicate that four highly conserved residues, H128, H149, Y223, and R239, are essential for catalysis. H128 functions as both the catalytic acid and base, H149 and R239 function as the neutralizers, and Y223 plays a supporting role in catalysis. Structural comparison and sequence alignment suggest that Uly1 and many other PL24 enzymes may directly bind the substrate near the catalytic residues for catalysis, different from the PL24 ulvan lyase LOR_107, which adopts a two-stage substrate binding process. This study provides new insights into ulvan lyases and ulvan degradation.

Item Details

Item Type:Refereed Article
Keywords:ulvan, ulvan lyase, polysaccharide lyase family 24, marine bacterium, substrate recognition, catalytic mechanism
Research Division:Biological Sciences
Research Group:Microbiology
Research Field:Microbial ecology
Objective Division:Environmental Management
Objective Group:Marine systems and management
Objective Field:Oceanic processes (excl. in the Antarctic and Southern Ocean)
UTAS Author:McMinn, A (Professor Andrew McMinn)
ID Code:145529
Year Published:2021
Deposited By:Ecology and Biodiversity
Deposited On:2021-07-26
Last Modified:2021-07-26
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