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J. Bacteriol., 09 1997, 5436-5441, Vol 179, No. 17
WW Lorenz and J Wiegel
The genes encoding acetyl xylan esterase 1 (axe1) and a beta-xylosidase
(xylB) have been cloned and sequenced from Thermoanaerobacterium sp. strain
JW/SL YS485. axe1 is located 22 nucleotides 3' of the xylB sequence. The
identity of axe1 was confirmed by comparison of the deduced amino acid
sequence to peptide sequence analysis data from purified acetyl xylan
esterase 1. The xylB gene was identified by expression cloning and by
sequence homology to known beta-xylosidases. Plasmids which independently
expressed either acetyl xylan esterase 1 (pAct1BK) or beta-xylosidase
(pXylo-1.1) were constructed in Escherichia coli. Plasmid pXylAct-1
contained both genes joined at a unique EcoRI site and expressed both
activities. Substrate specificity, pH, and temperature optima were
determined for partially purified recombinant acetyl xylan esterase 1 and
for crude recombinant beta- xylosidase. Similarity searches showed that the
axe1 and xylB genes were homologs of the ORF-1 and xynB genes,
respectively, isolated from Thermoanaerobacterium saccharolyticum. Although
the deduced sequence of the axe1 product had no significant amino acid
sequence similarity to any reported acetyl xylan esterase sequence, it did
have strong similarity to cephalosporin C deacetylase from Bacillus
subtilis. Recombinant acetyl xylan esterase 1 was found to have
thermostable deacetylase activity towards a number of acetylated
substrates, including cephalosporin C and 7-aminocephalosporanic acid.
Copyright © 1997, American Society for Microbiology
Isolation, analysis, and expression of two genes from Thermoanaerobacterium sp. strain JW/SL YS485: a beta-xylosidase and a novel acetyl xylan esterase with cephalosporin C deacetylase activity
Department of Microbiology, and Center for Biological Resource Recovery, University of Georgia, Athens 30602-2605, USA.
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