Novel modular endo-β-1,4-xylanase with transglycosylation activity from Cellulosimicrobium sp. strain HY-13 that is homologous to inverting GH family 6 enzymes.
The gene (2304-bp) encoding a novel xylanolytic enzyme (XylK2) with a catalytic domain, which is 70% identical to that of Cellulomonas flavigena DSM 20109 GH6 β-1,4-cellobiohydrolase, was identified from an earthworm (Eisenia fetida)-symbiotic bacterium, Cellulosimicrobium sp. strain HY-13. The enzyme consisted of an N-terminal catalytic GH6-like domain, a fibronectin type 3 (Fn3) domain, and a C-terminal carbohydrate-binding module 2 (CBM 2). XylK2ΔFn3-CBM 2 displayed high transferase activity (788.3 IU mg(-1)) toward p-nitrophenyl (PNP) cellobioside, but did not degrade xylobiose, glucose-based materials, or other PNP-sugar derivatives. Birchwood xylan was degraded by XylK2ΔFn3-CBM 2 to xylobiose (59.2%) and xylotriose (40.8%). The transglycosylation activity of the enzyme, which enabled the formation of xylobiose (33.6%) and xylotriose (66.4%) from the hydrolysis of xylotriose, indicates that it is not an inverting enzyme but a retaining enzyme. The endo-β-1,4-xylanase activity of XylK2ΔFn3-CBM 2 increased significantly by approximately 2.0-fold in the presence of 50mM xylobiose.
Industrial Bio-materials Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 305-806, Republic of Korea.
Do Young
DY
Kim
Su-Jin
SJ
Ham
Hyo Jeong
HJ
Kim
Jihoon
J
Kim
Mi-Hwa
MH
Lee
Han-Young
HY
Cho
Dong-Ha
DH
Shin
Young Ha
YH
Rhee
Kwang-Hee
KH
Son
Ho-Yong
HY
Park
D000595:Amino Acid Sequence; D001483:Base Sequence; D050260:Carbohydrate Metabolism; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry / Q000378:metabolism*; D006031:Glycosylation; D006090:Gram-Negative Bacteria / Q000145:classification / Q000201:enzymology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers; D011994:Recombinant Proteins; D043364:Endo-1,4-beta Xylanases