Bacteroides intestinalis DSM 17393 BiFae1B Putative uncharacterized protein
Comment
two gene fragments concatened Pfam A Esterase 61 282 Pfam A Esterase 421 645 Although the total sequence is really the esterase. In ESTHER only the second part which is complete is considered. The N-term is considered as a fragment
(Below N is a link to NCBI taxonomic web page and E link to ESTHER at designed phylum.) > cellular organisms: NE > Bacteria: NE > FCB group: NE > Bacteroidetes/Chlorobi group: NE > Bacteroidetes: NE > Bacteroidia: NE > Bacteroidales: NE > Bacteroidaceae: NE > Bacteroides: NE > Bacteroides intestinalis: NE > Bacteroides intestinalis DSM 17393: NE
LHGARAESNVRNSKYPQLTADHRAIFRIKAPDAQKVQIDLGRKYDMVRQE
GGIWETVTDSLGEGFHYYSLLIDGVAVSDPGSETFYGMGRMASGIEVPFK
GGEYYALKDVPHGDIRMKRYYSEVSRSWRRFFVYTPAGYDTRTAEKYPVL
YLLHGGGEDERGWATQGKTDLIIDNLIAEGKAKPMLIVMLDGNMASAGFN
AGALKAFEAELMQAVIPFVEDNYRVRKEADSRALAGLSMGGIQTLYAGLY
HTDLFAHLGVFSSGWLPFYQKIADGQYEFINKNKAAIDSQLRLLWIAMGG
KEDIAYQNCQNMLKEFDTLKLKYTYSEYPGGHTWPVWRNNLYNFAQLLFN
K
LegendThis sequence has been compared to family alignement (MSA) red => minority aminoacid blue => majority aminoacid color intensity => conservation rate title => sequence position(MSA position)aminoacid rate Catalytic site Catalytic site in the MSA LHGARAESNVRNSKYPQLTADHRAIFRIKAPDAQKVQIDLGRKYDMVRQE GGIWETVTDSLGEGFHYYSLLIDGVAVSDPGSETFYGMGRMASGIEVPFK GGEYYALKDVPHGDIRMKRYYSEVSRSWRRFFVYTPAGYDTRTAEKYPVL YLLHGGGEDERGWATQGKTDLIIDNLIAEGKAKPMLIVMLDGNMASAGFN AGALKAFEAELMQAVIPFVEDNYRVRKEADSRALAGLSMGGIQTLYAGLY HTDLFAHLGVFSSGWLPFYQKIADGQYEFINKNKAAIDSQLRLLWIAMGG KEDIAYQNCQNMLKEFDTLKLKYTYSEYPGGHTWPVWRNNLYNFAQLLFN K
Arabinoxylans are constituents of the human diet. Although not utilizable by the human host, they can be fermented by colonic bacteria. The arabinoxylan backbone is decorated with arabinose side chains that may be substituted with ferulic acid, thus limiting depolymerization to fermentable sugars. We investigated the polypeptides encoded by two genes upregulated during growth of the colonic bacterium Bacteroides intestinalis on wheat arabinoxylan. The recombinant proteins, designated BiFae1A and BiFae1B, were functionally assigned esterase activities. Both enzymes were active on acetylated substrates, although each showed a higher ferulic acid esterase activity on methyl-ferulate. BiFae1A showed a catalytic efficiency of 12mM s(-1) on para-nitrophenyl-acetate, and on methyl-ferulate, the value was 27 times higher. BiFae1B showed low catalytic efficiencies for both substrates. Furthermore, the two enzymes released ferulic acid from various structural elements, and NMR spectroscopy indicated complete de-esterification of arabinoxylan oligosaccharides from wheat bran. BiFae1A is a tetramer based on the crystal structure, whereas BiFae1B is a dimer in solution based on size exclusion chromatography. The structure of BiFae1A was solved to 1.98A resolution, and two tetramers were observed in the asymmetric unit. A flexible loop that may act as a hinge over the active site and likely coordinates critical interactions with the substrate was prominent in BiFae1A. Sequence alignments of the esterase domains in BiFae1B with the feruloyl esterase from Clostridium thermocellum suggest that both domains lack the flexible hinge in BiFae1A, an observation that may partly provide a molecular basis for the differences in activities in the two esterases.