His22 of TLXI plays a critical role in the inhibition of glycoside hydrolase family 11 xylanases.
Recently, a novel wheat thaumatin-like protein, TLXI, which inhibits microbial glycoside hydrolase family (GH) 11 xylanases has been identified. It is the first xylanase inhibitor that exerts its inhibition in a non-competitive way. In the present study we gained insight into the interaction between TLXI and xylanases via combined molecular modeling and mutagenic approaches. More specifically, site-specific mutation of His22, situated on a loop which distinguishes TLXI from other, non-inhibiting, thaumatin-like proteins, and subsequent expression of the mutant in Pichia pastoris resulted in a protein lacking inhibition capacity. The mutant protein was unable to form a complex with GH11 xylanases. Based on these findings, the interaction of TLXI with GH11 xylanases is discussed.
Rombouts
Sigrid
S
Laboratory of Gene Technology, Katholieke Universiteit Leuven, Leuven, Belgium.
Fierens
Ellen
E
Vandermarliere
Elien
E
Voet
Arnout
A
Gebruers
Kurt
K
Beaugrand
Johnny
J
Courtin
Christophe M
CM
Delcour
Jan A
JA
de Maeyer
Marc
M
Rabijns
Anja
A
Van Campenhout
Steven
S
Volckaert
Guido
G
D003001:Cloning, Molecular; D043364:Endo-1,4-beta Xylanases / Q000037:antagonists & inhibitors*; D006026:Glycoside Hydrolases / Q000037:antagonists & inhibitors; D006639:Histidine; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology*; D011485:Protein Binding; D014908:Triticum
D010940:Plant Proteins; D006639:Histidine; C003427:thaumatin protein, plant; D006026:Glycoside Hydrolases; D043364:Endo-1,4-beta Xylanases