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KMID : 0613820210310030356
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Journal of Life Science
2021 Volume.31 No. 3 p.356 ~ p.365
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Characterization of Exolytic GH50A β-Agarase and GH117A α-NABH Involved in Agarose Saccharification of Cellvibrio sp. KY-GH-1 and Possible Application to Mass Production of NA2 and L-AHG
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Jang Won-Young
Lee Hee-Kyoung
Kim Young-Ho
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Abstract
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Recently, we sequenced the entire genome of a freshwater agar-degrading bacterium Cellvibriosp. KY- GH-1 (KCTC13629BP) to explore genetic information encoding agarases that hydrolyze agarose into monomers 3,6-anhydro-L-galactose (L-AHG) and D-galactose. The KY-GH-1 strain appeared to possess nine β-agarase genes and two α-neoagarobiose hydrolase (α-NABH) genes in a 77-kb agarase gene cluster. Based on these genetic information, the KY-GH-1 strain-caused agarose degradation into L- AHG and D-galactose was predicted to be initiated by both endolytic GH16 and GH86 β-agarases to generate NAOS (NA4/NA6/NA8), and further processed by exolytic GH50 β-agarases to generate NA2, and then terminated by GH117 α-NABHs which degrade NA2 into L-AHG and D-galactose. More recently, by employing E. coliexpression system with pET-30a vector we obtained three recombinant His-tagged GH50 family β-agarases (GH50A, GH50B, and GH50C) derived from Cellvibriosp. KY-GH-1 to compare their enzymatic properties. GH50A β-agarase turned out to have the highest exolytic β-agarase activity among the three GH50 isozymes, catalyzing efficient NA2 production from the substrate (agarose, NAOS or AOS). Additionally, we determined that GH117A α-NABH, but not GH117B α-NABH, could potently degrade NA2 into L-AHG and D-galactose. Sequentially, we examined the enzymatic characteristics of GH50A β-agarase and GH117A α-NABH, and assessed their efficiency for NA2 production from agarose and for production of L-AHG and D-galactose from NA2, respectively. In this review, we describe the benefits of recombinant GH50A β-agarase and GH117A α-NABH originated from Cellvibriosp. KY-GH-1, which may be useful for the enzymatic hydrolysis of agarose for mass production of L-AHG and D-galactose.
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KEYWORD
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Agarase gene cluster, agarose saccharification, Cellvibrio sp. KY-GH-1, GH117A α-NABH, GH50A β-agarase
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