Cloning and sequencing of the cellobiose 2-epimerase gene from an obligatory anaerobe, Ruminococcus albus.
Cellobiose 2-epimerase (EC 5.1.3.11) was first identified in 1967 as an extracellular enzyme that catalyzes the reversible epimerization between cellobiose and 4-O-beta-D-glucopyranosyl-D-mannose in a culture broth of Ruminococcus albus 7 (ATCC 27210(T)). Here, for the first time, we describe the purification of cellobiose 2-epimerase from R. albus NE1. The enzyme was found to 2-epimerize the reducing terminal glucose moieties of cellotriose and cellotetraose in addition to cellobiose. The gene encoding cellobiose 2-epimerase comprises 1170 bp (389 amino acids) and is present as a single copy in the genome. The deduced amino acid sequence of the mature enzyme contains the possible catalytic residues Arg52, His243, Glu246, and His374. Sequence analysis shows the gene shares a very low level of homology with N-acetyl-D-glucosamine 2-epimerases (EC 5.1.3.8), but no significant homology to any other epimerases reported to date.
Ito
Shigeaki
S
Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, N-9, W-9, Kita-ku, Sapporo 060-8589, Japan.
Hamada
Shigeki
S
Yamaguchi
Kozo
K
Umene
Shingo
S
Ito
Hiroyuki
H
Matsui
Hirokazu
H
Ozawa
Tadahiro
T
Taguchi
Hidenori
H
Watanabe
Jun
J
Wasaki
Jun
J
Ito
Susumu
S
D000595:Amino Acid Sequence; D000693:Anaerobiosis; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D002238:Carbohydrate Epimerases / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D002475:Cellobiose / Q000378:metabolism*; D003001:Cloning, Molecular; D008969:Molecular Sequence Data; D045857:Ruminococcus / Q000201:enzymology* / Q000235:genetics*; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; D002475:Cellobiose; D002238:Carbohydrate Epimerases; C581214:cellobiose 2-epimerase, Ruminococcus albus