Exploring competitive inhibition of a family 10 xylanase derived from Hu sheep rumen microbiota by Oryza sativa xylanase inhibitor protein: In vitro and in silico perspectives.
Enzyme Microb Technol
; 160: 110082, 2022 Oct.
Article
em En
| MEDLINE
| ID: mdl-35709658
ABSTRACT
The catalytic domain of family GH10 xylanase, XYN-LXY_CD derived from Hu sheep rumen microbiota was expressed in Pichia pastoris X33. The special activity of reXYN-LXY_CD in the culture supernatant was 232.56 U/mg. The optima of reXYN-LXY_CD were 53 °C and pH 7.0. Recombinant Oryza sativa xylanase inhibitor protein (rePOsXIP) competitively inhibited reXYN-LXY_CD with an inhibition constant (Ki) value of 237.37 nM. The concentration of hydrolysates released from beechwood xylan by reXYN-LXY_CD reduced when rePOsXIP was added into the hydrolytic system. Fluorescence of reXYN-LXY_CD was statically quenched by rePOsXIP in a dose-dependent manner. The details in intermolecular interaction between XYN-LXY_CD and OsXIP were investigated by using molecular dynamics (MD) simulations, binding free energy computation and non-covalent interactions (NCI) analysis. Hydrogen bonding and van der Waals played indispensable roles in the XYN-LXY_CD/OsXIP interaction. The α-7 helix of OsXIP tightly occupied the catalytic pocket of XYN-LXY_CD with hydrogen bonding such as K239OsXIP-N261/Q292/E197XYN-LXY_CD (E197, the acid-base catalytic residue), D236OsXIP-K327XYN-LXY_CD and Q242OsXIP-E211/Q212XYN-LXY_CD. Based on the quantum theory of atoms in molecules (QTAIM), the Laplacian of electron density and core-valence bifurcation index of HZ3K239-OE2E197 were 0.1025 a.u. and 0.002218, respectively. Elucidating the mechanism underlying xylanase-inhibitor interactions might help construct XYN-LXY_CD mutants that gain resistance to XIPs and high catalytic activity, which would be more efficient in feed additives in livestock.
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MEDLINE
Assunto principal:
Oryza
/
Microbiota
Limite:
Animals
Idioma:
En
Ano de publicação:
2022
Tipo de documento:
Article