Involvement of the multidomain regulatory protein XynR in positive control of xylanase gene expression in the ruminal anaerobe Prevotella bryantii B(1)4

K Miyazaki, H Miyamoto, D K Mercer, T Hirase, J C Martin, Y Kojima, H J Flint

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40 Citations (Scopus)


The xylanase gene cluster from the rumen anaerobe Prevotella bryantii B(I)4 was found to include a gene (xynR) that encodes a multidomain regulatory protein and is downstream from the xylanase and P-xylosidase genes xynA and xynB. Additional genes identified upstream of xynA and xynB include xynD, which encodes an integral membrane protein that has homology with Na:solute symporters; xynE, which is related to the genes encoding acylhydrolases and arylesterases; and xynF, which has homology with the genes encoding alpha-glucuronidases. XynR includes, in a single 833-amino-acid polypeptide, a putative input domain unrelated to other database sequences, a likely transmembrane domain, histidine kinase motifs, response regulator sequences, and a C-terminal AraC-type helix-turn-helix DNA binding domain. Two transcripts (3.7 and 5.8 kb) were detected with a xynA probe, and the start site of the 3.7-kb transcript encoding xynABD was mapped to a position upstream of xynD. The DNA binding domain of XynR was purified after amplification and overexpression in Escherichia coli and was found to bind to a 141-bp DNA fragment from the region immediately upstream of xynD. In vitro transcription assays demonstrated that XynR stimulates transcription of the 3.7-kb transcript. We concluded that XynR acts as a positive regulator that activates expression of xynABD in P. bryantii B(I)4. This is the first regulatory protein that demonstrates significant homology with the two-component regulatory protein superfamily and has been shown to be involved in the regulation of polysaccharidase gene expression.

Original languageEnglish
Pages (from-to)2219-2226
Number of pages8
JournalJournal of Bacteriology
Issue number7
Publication statusPublished - Apr 2003


  • bacteroides-thetaiotaomicron
  • signal-transduction
  • membrane-proteins
  • Escherichia-Coli
  • bacteria
  • ruminicola
  • rumen
  • breakdown
  • degradation
  • xylosidase

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