Previous Article | Next Article ![]()
Appl Environ Microbiol, May 1998, p. 1759-1765, Vol. 64, No. 5
Centre for Gene Technology,
Received 30 December 1997/Accepted 23 January 1998
A two-step PCR protocol was used to identify and sequence a family
11 xylanase gene from Dictyoglomus thermophilum Rt46B.1. Family 11 xylanase consensus fragments (GXCFs) were amplified from
Rt46B.1 genomic DNA by using different sets of consensus PCR primers
that exhibited broad specificity for conserved motifs within fungal
and/or bacterial family 11 xylanase genes. On the basis of the
sequences of a representative sample of the GXCFs a single family 11 xylanase gene (xynB) was identified. The entire gene
sequence was obtained in the second step by using genomic walking PCR
to amplify Rt46B.1 genomic DNA fragments upstream and downstream of the
xynB GXCF region. The putative XynB peptide (Mr, 39,800) encoded by the Rt46B.1
xynB open reading frame was a multidomain enzyme comprising
an N-terminal catalytic domain (Mr, 22,000) and
a possible C-terminal substrate-binding domain (Mr, 13,000) that were separated by a short
serine-glycine-rich 23-amino-acid linker peptide. Seven xylanases which
differed at their N and C termini were produced from different
xynB expression plasmids. All seven xylanases exhibited
optimum activity at pH 6.5. However, the temperature optima of the XynB
xylanases varied from 70 to 85°C. Pretreatment of Pinus
radiata and eucalypt kraft-oxygen pulps with XynB resulted in
moderate xylan solubilization and a substantial improvement in the
bleachability of these pulps.
0099-2240/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Cloning of the xynB Gene from
Dictyoglomus thermophilum Rt46B.1 and Action of the Gene
Product on Kraft Pulp
*
Corresponding author. Mailing address: Research Office,
Macquarie University, Sydney, New South Wales 2109, Australia. Phone: 61 2 9850 8614. Fax: 61 2 9850 8799. E-mail:
peter.bergquist{at}mq.edu.au.
Appl Environ Microbiol, May 1998, p. 1759-1765, Vol. 64, No. 5
0099-2240/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»