The mannobiose-forming exo-mannanase involved in a new mannan catabolic pathway in Bacteroides fragilis
- 527 Downloads
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.
KeywordsBacteroides fragilis Mannanase Mannobiose 2-epimerase Mannosylglucose phosphorylase
This study was partly supported by the Special Coordination Funds for Promoting Science and Technology from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.
- Cerdeño-Tárraga AM, Patrick S, Crossman LC, Blakely G, Abratt V, Lennard N, Poxton I, Duerden B, Harris B, Quail MA, Barron A, Clark L, Corton C, Doggett J, Holden MT, Larke N, Line A, Lord A, Norbertczak H, Ormond D, Price C, Rabbinowitsch E, Woodward J, Barrell B, Parkhill J (2005) Extensive DNA inversions in the B. fragilis genome control variable gene expression. Science 307:1463–1465PubMedCrossRefGoogle Scholar
- DeBoy RT, Mongodin EF, Fouts DE, Tailford LE, Khouri H, Emerson J, Mohamoud Y, Watkins K, Henrissat B, Gilbert HJ, Nelson KE (2008) Insights into plant cell wall degradation from the genome sequence of the soil bacterium Cellvibrio japonicus. J Bacteriol 190:5455–5463PubMedCentralPubMedCrossRefGoogle Scholar
- Dias FMV, Vincent F, Pell G, Prates JAM, Centeno MSJ, Tailford LE, Ferreira LMA, Fontes CMGA, Davies GJ, Gilbert HJ (2004) Insights into the molecular determinants of substrate specificity in glycoside hydrolase family 5 revealed by the crystal structure and kinetics of Cellvibrio mixtus mannosidase 5A. J Biol Chem 279:25517–25526PubMedCrossRefGoogle Scholar
- Hatada Y, Takeda N, Hirasawa K, Ohta Y, Usami R, Yoshida Y, Grant WD, Ito S, Horikoshi K (2005) Sequence of the gene for a high-alkaline mannanase from an alkaliphilic Bacillus sp. Strain JAMB-750, its expression in Bacillus subtilis and characterization of the recombinant enzyme. Extremophiles 9:497–500PubMedCrossRefGoogle Scholar
- Ito S, Taguchi H, Hamada S, Kawauchi S, Ito H, Senoura T, Watanabe J, Nishimukai M, Ito S, Matsui H (2008) Enzymatic properties of cellobiose 2-epimerase from Ruminococcus albus and the synthesis of rare oligosaccharides by the enzyme. Appl Microbiol Biotechnol 79:433–441PubMedCrossRefGoogle Scholar
- McCleary BV (1988) Carob and guar galactomannans. Methods Enzymol 160:523–527Google Scholar