AUTHOR=Guan Lijun , Wang Kunlun , Gao Yang , Li Jialei , Yan Song , Ji Nina , Ren Chuanying , Wang Jiayou , Zhou Ye , Li Bo , Lu Shuwen 

TITLE=Biochemical and Structural Characterization of a Novel Bacterial Tannase From Lachnospiraceae bacterium in Ruminant Gastrointestinal Tract

JOURNAL=Frontiers in Bioengineering and Biotechnology

VOLUME=9

YEAR=2021

URL=https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2021.806788

DOI=10.3389/fbioe.2021.806788

ISSN=2296-4185

ABSTRACT=<p>Tannases are a family of esterases that catalyze the hydrolysis of ester and depside bonds present in hydrolyzable tannins to release gallic acid. Here, a novel tannase from <italic>Lachnospiraceae bacterium</italic> (TanA<sub>Lb</sub>) was characterized. The recombinant TanA<sub>Lb</sub> exhibited maximal activity at pH 7.0 and 50°C, and it maintained more than 70% relative activity from 30°C to 55°C. The activity of TanA<sub>Lb</sub> was enhanced by Mg<sup>2+</sup> and Ca<sup>2+</sup>, and was dramatically reduced by Cu<sup>2+</sup> and Mn<sup>2+</sup>. TanA<sub>Lb</sub> is capable of degrading esters of phenolic acids with long-chain alcohols, such as lauryl gallate as well as tannic acid. The <italic>K</italic>m value and catalytic efficiency (<italic>k</italic><sub>cat</sub> /<italic>K</italic>m) of TanA<sub>Lb</sub> toward five substrates showed that tannic acid (TA) was the favorite substrate. Homology modeling and structural analysis indicated that TanA<sub>Lb</sub> contains an insertion loop (residues 341–450). Based on the moleculer docking and molecular dynamics (MD) simulation, this loop was observed as a flap-like lid to interact with bulk substrates such as tannic acid. TanA<sub>Lb</sub> is a novel bacterial tannase, and the characteristics of this enzyme make it potentially interesting for industrial use.</p>