Molecular identification of wheat endoxylanase inhibitor TAXI-I1, member of a new class of plant proteins.
Triticum aestivum endoxylanase inhibitors (TAXIs) are wheat proteins that inhibit family 11 endoxylanases commonly used in different (bio)technological processes. Here, we report on the identification of the TAXI-I gene which encodes a mature protein of 381 amino acids with a calculated molecular mass of 38.8 kDa. When expressed in Escherichia coli, the recombinant protein had the specificity and inhibitory activity of natural TAXI-I, providing conclusive evidence that the isolated gene encodes an endoxylanase inhibitor. Bioinformatical analysis indicated that no conserved domains nor motifs common to other known proteins are present. Sequence analysis revealed similarity with a glycoprotein of carrot and with gene families in Arabidopsis thaliana and rice, all with unknown functions. Our data indicate that TAXI-I belongs to a newly identified class of plant proteins for which a molecular function as glycoside hydrolase inhibitor can now be suggested.
Fierens
Katleen
K
Laboratory of Food Chemistry, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, B-3001 Leuven, Belgium. katleen.fierens@agr.kuleuven.ac.be
Brijs
Kristof
K
Courtin
Christophe M
CM
Gebruers
Kurt
K
Goesaert
Hans
H
Raedschelders
Gert
G
Robben
Johan
J
Van Campenhout
Steven
S
Volckaert
Guido
G
Delcour
Jan A
JA
D000595:Amino Acid Sequence; D001483:Base Sequence; D018744:DNA, Plant; D004591:Electrophoresis, Polyacrylamide Gel; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics; D010957:Plasmids; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D014908:Triticum / Q000737:chemistry*
D018744:DNA, Plant; D010940:Plant Proteins; D011994:Recombinant Proteins; C422246:TAXI I protein, Triticum aestivum