Identification and characterization of two xyloglucan-specific endo-1,4-glucanases in Aspergillus oryzae
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BIOTECHNOLOGICALLY RELEVANT ENZYMES AND PROTEINS
Identification and characterization of two xyloglucan-specific endo-1,4-glucanases in Aspergillus oryzae Tomohiko Matsuzawa 1
&
Akihiko Kameyama 2 & Yusuke Nakamichi 3 & Katsuro Yaoi 1
Received: 6 July 2020 / Revised: 13 August 2020 / Accepted: 2 September 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Aspergillus oryzae produces glycoside hydrolases to degrade xyloglucan. We identified and characterized two xyloglucanspecific endo-1,4-glucanases (xyloglucanases) named Xeg12A and Xeg5A. Based on their amino acid sequences, Xeg12A and Xeg5A were classified into glycoside hydrolase families GH12 and GH5, respectively. Xeg12A degrades tamarind seed xyloglucan polysaccharide into xyloglucan oligosaccharides containing four glucopyranosyl residues as main chains, including heptasaccharides (XXXG: Glc4Xyl3), octasaccharides (XXLG and XLXG: Glc4Xyl3Gal1), and nonasaccharides (XLLG: Glc4Xyl3Gal2). By contrast, Xeg5A produces various xyloglucan oligosaccharides from xyloglucan. Xeg5A hydrolyzes xyloglucan into not only XXXG, XXLG/XLXG, and XLLG but also disaccharides (isoprimeverose: Glc1Xyl1), tetrasaccharides (XX: Glc2Xyl2 and LG: Glc2Xyl1Gal1), and so on. Xeg12A is a typical endo-dissociative-type xyloglucanase that repeats hydrolysis and desorption from xyloglucan. Conversely, Xeg5A acts as an endo-processive-type xyloglucanase that hydrolyzes xyloglucan progressively without desorption. These results indicate that although both Xeg12A and Xeg5A contribute to the degradation of xyloglucan, they have different modes of activity toward xyloglucan, and the hydrolysis machinery of Xeg5A is unique compared with that of other known GH5 enzymes. Key points • We identified two xyloglucanases, Xeg12A and Xeg5A, in A. oryzae. • Modes of activity and regiospecificities of Xeg12A and Xeg5A were clearly different. • Xeg5A is a unique xyloglucanase that produces low-molecular-weight oligosaccharides. Keywords Xyloglucanase . Xyloglucan . Aspergillus oryzae . Oligosaccharide . Glycoside hydrolase
Introduction Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00253-020-10883-7) contains supplementary material, which is available to authorized users. * Tomohiko Matsuzawa [email protected] 1
Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
2
Biotechnology Research Institute for Drug Discovery, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
3
Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 3-11-32, Kagamiyama, HigashiHiroshima, Hiroshima 739-0046, Japan
Xyloglucan is a major polysaccharide found in the cell wall and seeds of plants. It has β-1,4-glucan as the main chain, and the glucopyranosyl residues are modified with α-1,6-linked xylopyranosyl re
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