An Aspergillus nidulans β-mannanase with high transglycosylation capacity revealed through comparative studies within glycosidase family 5

Abstract

β-Mannanases are involved in the conversion and modification of mannan-based saccharides. Using a retaining mechanism, they can, in addition to hydrolysis, also potentially perform transglycosylation reactions, synthesizing new glyco-conjugates. Transglycosylation has been reported for β-mannanases in GH5 and GH113. However, although they share the same fold and catalytic mechanism, there may be differences in the enzymes’ ability to perform transglycosylation. Three GH5 β-mannanases from Aspergillus nidulans, AnMan5A, AnMan5B and AnMan5C, which belong to subfamily GH5_7 were studied. Comparative studies, including the GH5_7 TrMan5A from Trichoderma reesei, showed some differences between the enzymes. All the enzymes could perform transglycosylation but AnMan5B stood out in generating comparably higher amounts of transglycosylation products when incubated with manno-oligosaccharides. In addition, AnMan5B did not use alcohols as acceptor, which was also different compared to the other three β-mannanases. In order to map the preferred binding of manno-oligosaccharides, incubations were performed in H218O. AnMan5B in contrary to the other enzymes did not generate any 18O-labelled products. This further supported the idea that AnMan5B potentially prefers to use saccharides as acceptor instead of water. A homology model of AnMan5B showed a non-conserved Trp located in subsite +2, not present in the other studied enzymes. Strong aglycone binding seems to be important for transglycosylation with saccharides. Depending on the application, it is important to select the right enzyme.Electronic supplementary materialThe online version of this article (doi:10.1007/s00253-014-5871-8) contains supplementary material, which is available to authorized users.

A novel strategy for efficient disaccharides synthesis from glucose by β-glucosidase

“…2B, I177 is located in +2 site and then W173 and I174 are located in +1 site. Our results were consistent with previous report that the position of amino acid residue as well as I ah value has an important in uence on the disaccharides synthesis (Rosengren et al, 2014). We speculated that I177 has a more signi cant in uence on the entrance of glucose and the release of disaccharides, compared to W173 and I174 owe to +2 site is closer to the entrance of enzyme, compared to +1 site.…”

A Single Point Mutation Alters the Transglycosylation/Hydrolysis Partition, Significantly Enhancing the Synthetic Capability of an endo-Glycoceramidase

“…13,14,[56][57][58][59] Therefore, the fact that the substitution of D311 by a tyrosine procured higher transglycosylation capability in EGC is consistent with previous findings and undoubtedly results from the increased hydrophobicity and bulkiness in the aglycone subsite, notably +1. [60][61][62][63] These specific properties of tyrosine could alter the enzyme's behavior in several ways. Firstly, the Y311 and Y306 might stack sandwich-wise with the CNP moiety of the donor (Figure 6), an interaction that would explain the lowered K M value of D311Y-catalyzed hydrolysis of CNP-β-Celb and, inversely, is inferred by the lowered transglycosylation level of D311Y when using F-β-Celb, a donor that lacks an aromatic aglycon moiety.…”

Peer Review #2 of "Production and purification of mannan oligosaccharide with epithelial tight junction enhancing activity (v0.1)"

“…Hence, different types of substrate and reaction condition affect the characteristics of MOS product (Ganter et al 1995) Recently, the production of MOS by enzymatic hydrolysis is of great interested since the product obtained has become more specific and predictable. The enzyme mainly used in the process is beta-mannanase that was found in many organisms including fungus, yeast, and bacteria (Bourgault & Bewley 2002;Chauhan et al 2012;Cheng et al 2016;Kim et al 2018;Kurakake & Komaki 2001;Larsson et al 2006;Puchart et al 2004;Rosengren et al 2014;Shi et al 2011;Talbot & Sygusch 1990). Beta-mannosidase (E.C.…”