Properties of two fungal endo-β-1,3-galactanases and their synergistic action with an exo-β-1,3-galactanase in degrading arabinogalactan-proteins

Substrate specificity of novel GH16 endo-β-(1→3)-galactanases acting on linear and branched β-(1→3)-galactooligosaccharides

“…The observed pH and temperature optima for NfEn3GAL at pH 5 and 40 °C were similar to those reported by Kotake et al (Kotake et al, 2011) and Yoshimi et al (Yoshimi et al, 2017), where the pH optima for the endo-β-(1→3)-galactanases FvEn3GAL, NcEn3GAL and Af3G were between pH 4 and 5.5 and the temperature optima for their enzymatic reaction were found to be 40-45 ˚C. In pH values below 3 and over 8 NfEn3GAL was not active.…”

“…The authors identified the first endoβ-(1→3)-galactanase (FvEn3GAL) from the winter mushroom Flammulina velutipes which was subsequently cloned, purified and characterized. Two homologous endo-β-(1→3)-galactanases (45-46% sequence homology to FvEn3GAL) from Aspergillus flavusi (Af3G) and from Neurospora crassa (NcEn3GAL) were recently expressed in Pichia pastoris, purified and characterized (Yoshimi et al, 2017). All three enzymes specifically hydrolyse β-(1→3)-galactan and β-(1→3)-galactooligosaccharides with degree of polymerization of at least three (Kotake et al, 2011;Yoshimi et al, 2017).…”

“…Two homologous endo-β-(1→3)-galactanases (45-46% sequence homology to FvEn3GAL) from Aspergillus flavusi (Af3G) and from Neurospora crassa (NcEn3GAL) were recently expressed in Pichia pastoris, purified and characterized (Yoshimi et al, 2017). All three enzymes specifically hydrolyse β-(1→3)-galactan and β-(1→3)-galactooligosaccharides with degree of polymerization of at least three (Kotake et al, 2011;Yoshimi et al, 2017). However, the enzymes only have trace activity towards native gum arabic, probably because branching at the 6-position prevents them from accessing the β-(1→3)-galactan main chains.…”

“…Apart from FvEn3GAL, NcEn3GAL and Af3G, no other endo-β-(1→3)-galactanases have been described in the literature. Endo-β-(1→3)-galactanases could be relevant industrially due to their potential to process AGP, gum arabic or larchwood arabinogalactan, possibly in combination with auxiliary, debranching enzymes such as endo-β-(1→6)-galactanases, α-L-arabinofuranosidases and α-L-rhamnosidases (Sakamoto and Ishimaru, 2013;Yoshimi et al, 2017).…”

Expression of a fungal exo-β-1,3-galactanase in Arabidopsis reveals a role of type II arabinogalactans in the regulation of cell shape

“…For the analysis of action of recombinant enzymes expressed in Pichia yeast, rIl3GAL and rIl3GAL-PM were reacted with 1 mg ml –1 AGPs from radish leaves in 50 mM sodium acetate buffer (pH 5.0) at 37 °C. Released Gal and oligosaccharides were derivatized with p -aminobenzoic acid ethyl ester (ABEE; Wako, Osaka, Japan) ( Matsuura and Imaoka, 1988 ), and detected by HPLC as previously described ( Yoshimi et al , 2017 ). ABEE-labeled isomaltooligosaccharides (IMOs) were used as molecular makers for the elution positions ( Konishi et al , 2007 ).…”