The mannobiose-forming exo-mannanase involved in a new mannan catabolic pathway in Bacteroides fragilis.
We have proposed a new mannan catabolic pathway in Bacteroides fragilis NCTC 9343 that involves a putative mannanase ManA in glycoside hydrolase family 26 (BF0771), a mannobiose and/or sugar transporter (BF0773), mannobiose 2-epimerase (BF0774), and mannosylglucose phosphorylase (BF0772). If this hypothesis is correct, ManA has to generate mannobiose from mannans as the major end product. In this study, the BF0771 gene from the B. fragilis genome was cloned and expressed in Escherichia coli cells. The expressed protein was found to produce mannobiose exclusively from mannans and initially from manno-oligosaccharides. Production of 4-O-β-D-glucopyranosyl-D-mannose or 4-O-β-D-mannopyranosyl-D-glucose from mannans was not detectable. The results indicate that this enzyme is a novel mannobiose-forming exo-mannanase, consistent with the new microbial mannan catabolic pathway we proposed.
Department of Bioscience and Biotechnology, Faculty of Agriculture, University of the Ryukyus, 1, Senbaru, Nishihara, Okinawa, 903-0213, Japan.
Kazuki
K
Kawaguchi
Takeshi
T
Senoura
Shigeaki
S
Ito
Toki
T
Taira
Hiroyuki
H
Ito
Jun
J
Wasaki
Susumu
S
Ito
D001441:Bacteroides fragilis / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D008351:Mannans / Q000096:biosynthesis / Q000378:metabolism*; D008361:Mannosidases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D009844:Oligosaccharides / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics; D013696:Temperature
D008351:Mannans; D009844:Oligosaccharides; D011994:Recombinant Proteins; C014647:mannobiose; D008361:Mannosidases