This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Emami, K.
Right arrow Articles by Gilbert, H. J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Emami, K.
Right arrow Articles by Gilbert, H. J.

 Previous Article  |  Next Article 

Journal of Bacteriology, August 2002, p. 4124-4133, Vol. 184, No. 15
0021-9193/02/$04.00+0     DOI: 10.1128/JB.184.15.4124-4133.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.

Evidence for Temporal Regulation of the Two Pseudomonas cellulosa Xylanases Belonging to Glycoside Hydrolase Family 11

Kaveh Emami,1 Tibor Nagy,1 Carlos M. G. A. Fontes,2 Luis M. A. Ferreira,2 and Harry J. Gilbert1*

Department of Biological and Nutritional Sciences, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU, United Kingdom,1 CIISA-Faculdade de Medicina Veterinaria, 1199 Lisboa Codex, Portugal2

Received 7 January 2002/ Accepted 7 May 2002

Pseudomonas cellulosa is a highly efficient xylan-degrading bacterium. Genes encoding five xylanases, and several accessory enzymes, which remove the various side chains that decorate the xylan backbone, have been isolated from the pseudomonad and characterized. The xylanase genes consist of xyn10A, xyn10B, xyn10C, xyn10D, and xyn11A, which encode Xyn10A, Xyn10B, Xyn10C, Xyn10D, and Xyn11A, respectively. In this study a sixth xylanase gene, xyn11B, was isolated which encodes a 357-residue modular enzyme, designated Xyn11B, comprising a glycoside hydrolase family 11 catalytic domain appended to a C-terminal X-14 module, a homologue of which binds to xylan. Localization studies showed that the two xylanases with glycoside hydrolase family (GH) 11 catalytic modules, Xyn11A and Xyn11B, are secreted into the culture medium, whereas Xyn10C is membrane bound. xyn10C, xyn10D, xyn11A, and xyn11B were all abundantly expressed when the bacterium was cultured on xylan or ß-glucan but not on medium containing mannan, whereas glucose repressed transcription of these genes. Although all of the xylanase genes were induced by the same polysaccharides, temporal regulation of xyn11A and xyn11B was apparent on xylan-containing media. Transcription of xyn11A occurred earlier than transcription of xyn11B, which is consistent with the predicted mode of action of the encoded enzymes. Xyn11A, but not Xyn11B, exhibits xylan esterase activity, and the removal of acetate side chains is required for xylanases to hydrolyze the xylan backbone. A transposon mutant of P. cellulosa in which xyn11A and xyn11B were inactive displayed greatly reduced extracellular but normal cell-associated xylanase activity, and its growth rate on medium containing xylan was indistinguishable from wild-type P. cellulosa. Based on the data presented here, we propose a model for xylan degradation by P. cellulosa in which the GH11 enzymes convert decorated xylans into substituted xylooligosaccharides, which are then hydrolyzed to their constituent sugars by the combined action of cell-associated GH10 xylanases and side chain-cleaving enzymes.

* Corresponding author. Mailing address: Department of Biological and Nutritional Sciences, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU, United Kingdom. Phone: 44(191)2226962. Fax: 44(191)2228684. E-mail: H.J.Gilbert{at}Newcastle.ac.uk.

Journal of Bacteriology, August 2002, p. 4124-4133, Vol. 184, No. 15
0021-9193/02/$04.00+0     DOI: 10.1128/JB.184.15.4124-4133.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Emami, K., Topakas, E., Nagy, T., Henshaw, J., Jackson, K. A., Nelson, K. E., Mongodin, E. F., Murray, J. W., Lewis, R. J., Gilbert, H. J. (2009). Regulation of the Xylan-degrading Apparatus of Cellvibrio japonicus by a Novel Two-component System. J. Biol. Chem. 284: 1086-1096 [Abstract] [Full Text]  
  • Cartmell, A., Topakas, E., Ducros, V. M-A., Suits, M. D. L., Davies, G. J., Gilbert, H. J. (2008). The Cellvibrio japonicus Mannanase CjMan26C Displays a Unique exo-Mode of Action That Is Conferred by Subtle Changes to the Distal Region of the Active Site. J. Biol. Chem. 283: 34403-34413 [Abstract] [Full Text]  
  • DeBoy, R. T., Mongodin, E. F., Fouts, D. E., Tailford, L. E., Khouri, H., Emerson, J. B., Mohamoud, Y., Watkins, K., Henrissat, B., Gilbert, H. J., Nelson, K. E. (2008). Insights into Plant Cell Wall Degradation from the Genome Sequence of the Soil Bacterium Cellvibrio japonicus. J. Bacteriol. 190: 5455-5463 [Abstract] [Full Text]  
  • Andrews, S. R., Taylor, E. J., Pell, G., Vincent, F., Ducros, V. M.-A., Davies, G. J., Lakey, J. H., Gilbert, H. J. (2004). The Use of Forced Protein Evolution to Investigate and Improve Stability of Family 10 Xylanases: THE PRODUCTION OF Ca2+-INDEPENDENT STABLE XYLANASES. J. Biol. Chem. 279: 54369-54379 [Abstract] [Full Text]  
  • Pell, G., Szabo, L., Charnock, S. J., Xie, H., Gloster, T. M., Davies, G. J., Gilbert, H. J. (2004). Structural and Biochemical Analysis of Cellvibrio japonicus Xylanase 10C: HOW VARIATION IN SUBSTRATE-BINDING CLEFT INFLUENCES THE CATALYTIC PROFILE OF FAMILY GH-10 XYLANASES. J. Biol. Chem. 279: 11777-11788 [Abstract] [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»