A bifunctional xylanase encoded by the xynA gene of the rumen cellulolytic bacterium Ruminococcus flavefaciens M comprises two dissimilar domains linked by an asparagine/glutamine-rich sequence

Jun-Xian Zhang, Harry J Flint

Research output: Contribution to journalArticle

68 Citations (Scopus)

Abstract

The nucleotide sequence of the xynA gene of Ruminococcus flavefaciens 17 was determined and found to consist of a 2862bp open reading frame beginning with a TTG start codon. The predicted product, XYLA, consisted of distinct amino-terminal (A) and carboxy terminal (C) domains (248 amino acids, including a putative signal sequence, and 332 amino acids, respectively) linked by a repetitive sequence (B, 374 amino acids) extraordinarily rich in asparagine (45%) and glutamine (26%) residues. Domains A and C were shown to be capable of expressing xylanase activity independently of each other when suitably truncated derivatives of the xynA coding region were expressed as lacZ fusions. The activities associated with the two domains were shown to differ with respect to the average size of hydrolysis products formed from oat-spelt xylan, with domain C releasing relatively more xylose and domain A more xylo-oligosaccharides. The amino acid sequence of domain A of XYLA closely resembled that of the Bacillus pumilus xynA enzyme (45% identical residues). On the other hand domain C showed significant similarity (33% to 40% identical residues) to a different group of bacterial xylanases and exoglucanases exemplified by the Caldocellum saccharolyticum xynA and celB products. The xynA product is, therefore, a bifunctional enzyme having two dissimilar catalytic domains capable of acting on xylan.

Original languageEnglish
Pages (from-to)1013-1023
Number of pages11
JournalMolecular Microbiology
Volume6
Issue number8
DOIs
Publication statusPublished - Apr 1992

Keywords

  • Ruminococcus-flavefaciens FD-1
  • thermophile caldocellum-saccharolyticum
  • nucleotide-sequence
  • clostridium-thermocellum
  • molecular-cloning
  • bacillus-pumilus
  • Escherichia-coli
  • expression
  • cellulase

Cite this

@article{69cce80c27b84f6cbc5b07883b57d7b5,
title = "A bifunctional xylanase encoded by the xynA gene of the rumen cellulolytic bacterium Ruminococcus flavefaciens M comprises two dissimilar domains linked by an asparagine/glutamine-rich sequence",
abstract = "The nucleotide sequence of the xynA gene of Ruminococcus flavefaciens 17 was determined and found to consist of a 2862bp open reading frame beginning with a TTG start codon. The predicted product, XYLA, consisted of distinct amino-terminal (A) and carboxy terminal (C) domains (248 amino acids, including a putative signal sequence, and 332 amino acids, respectively) linked by a repetitive sequence (B, 374 amino acids) extraordinarily rich in asparagine (45{\%}) and glutamine (26{\%}) residues. Domains A and C were shown to be capable of expressing xylanase activity independently of each other when suitably truncated derivatives of the xynA coding region were expressed as lacZ fusions. The activities associated with the two domains were shown to differ with respect to the average size of hydrolysis products formed from oat-spelt xylan, with domain C releasing relatively more xylose and domain A more xylo-oligosaccharides. The amino acid sequence of domain A of XYLA closely resembled that of the Bacillus pumilus xynA enzyme (45{\%} identical residues). On the other hand domain C showed significant similarity (33{\%} to 40{\%} identical residues) to a different group of bacterial xylanases and exoglucanases exemplified by the Caldocellum saccharolyticum xynA and celB products. The xynA product is, therefore, a bifunctional enzyme having two dissimilar catalytic domains capable of acting on xylan.",
keywords = "Ruminococcus-flavefaciens FD-1, thermophile caldocellum-saccharolyticum, nucleotide-sequence, clostridium-thermocellum, molecular-cloning, bacillus-pumilus, Escherichia-coli, expression, cellulase",
author = "Jun-Xian Zhang and Flint, {Harry J}",
year = "1992",
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journal = "Molecular Microbiology",
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TY - JOUR

T1 - A bifunctional xylanase encoded by the xynA gene of the rumen cellulolytic bacterium Ruminococcus flavefaciens M comprises two dissimilar domains linked by an asparagine/glutamine-rich sequence

AU - Zhang, Jun-Xian

AU - Flint, Harry J

PY - 1992/4

Y1 - 1992/4

N2 - The nucleotide sequence of the xynA gene of Ruminococcus flavefaciens 17 was determined and found to consist of a 2862bp open reading frame beginning with a TTG start codon. The predicted product, XYLA, consisted of distinct amino-terminal (A) and carboxy terminal (C) domains (248 amino acids, including a putative signal sequence, and 332 amino acids, respectively) linked by a repetitive sequence (B, 374 amino acids) extraordinarily rich in asparagine (45%) and glutamine (26%) residues. Domains A and C were shown to be capable of expressing xylanase activity independently of each other when suitably truncated derivatives of the xynA coding region were expressed as lacZ fusions. The activities associated with the two domains were shown to differ with respect to the average size of hydrolysis products formed from oat-spelt xylan, with domain C releasing relatively more xylose and domain A more xylo-oligosaccharides. The amino acid sequence of domain A of XYLA closely resembled that of the Bacillus pumilus xynA enzyme (45% identical residues). On the other hand domain C showed significant similarity (33% to 40% identical residues) to a different group of bacterial xylanases and exoglucanases exemplified by the Caldocellum saccharolyticum xynA and celB products. The xynA product is, therefore, a bifunctional enzyme having two dissimilar catalytic domains capable of acting on xylan.

AB - The nucleotide sequence of the xynA gene of Ruminococcus flavefaciens 17 was determined and found to consist of a 2862bp open reading frame beginning with a TTG start codon. The predicted product, XYLA, consisted of distinct amino-terminal (A) and carboxy terminal (C) domains (248 amino acids, including a putative signal sequence, and 332 amino acids, respectively) linked by a repetitive sequence (B, 374 amino acids) extraordinarily rich in asparagine (45%) and glutamine (26%) residues. Domains A and C were shown to be capable of expressing xylanase activity independently of each other when suitably truncated derivatives of the xynA coding region were expressed as lacZ fusions. The activities associated with the two domains were shown to differ with respect to the average size of hydrolysis products formed from oat-spelt xylan, with domain C releasing relatively more xylose and domain A more xylo-oligosaccharides. The amino acid sequence of domain A of XYLA closely resembled that of the Bacillus pumilus xynA enzyme (45% identical residues). On the other hand domain C showed significant similarity (33% to 40% identical residues) to a different group of bacterial xylanases and exoglucanases exemplified by the Caldocellum saccharolyticum xynA and celB products. The xynA product is, therefore, a bifunctional enzyme having two dissimilar catalytic domains capable of acting on xylan.

KW - Ruminococcus-flavefaciens FD-1

KW - thermophile caldocellum-saccharolyticum

KW - nucleotide-sequence

KW - clostridium-thermocellum

KW - molecular-cloning

KW - bacillus-pumilus

KW - Escherichia-coli

KW - expression

KW - cellulase

U2 - 10.1111/j.1365-2958.1992.tb02167.x

DO - 10.1111/j.1365-2958.1992.tb02167.x

M3 - Article

VL - 6

SP - 1013

EP - 1023

JO - Molecular Microbiology

JF - Molecular Microbiology

SN - 0950-382X

IS - 8

ER -