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Journal of Bacteriology, December 2007, p. 8863-8870, Vol. 189, No. 24
0021-9193/07/$08.00+0     doi:10.1128/JB.01141-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Structure, Function, and Regulation of the Aldouronate Utilization Gene Cluster from Paenibacillus sp. Strain JDR-2{triangledown}

Virginia Chow, Guang Nong, and James F. Preston*

Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida

Received 18 July 2007/ Accepted 24 September 2007

Direct bacterial conversion of the hemicellulose fraction of hardwoods and crop residues to biobased products depends upon extracellular depolymerization of methylglucuronoxylan (MeGAXn), followed by assimilation and intracellular conversion of aldouronates and xylooligosaccharides to fermentable xylose. Paenibacillus sp. strain JDR-2, an aggressively xylanolytic bacterium, secretes a multimodular cell-associated GH10 endoxylanase (XynA1) that catalyzes depolymerization of MeGAXn and rapidly assimilates the principal products, β-1,4-xylobiose, β-1,4-xylotriose, and MeGAX3, the aldotetrauronate 4-O-methylglucuronosyl-{alpha}-1,2-xylotriose. Genomic libraries derived from this bacterium have now allowed cloning and sequencing of a unique aldouronate utilization gene cluster comprised of genes encoding signal transduction regulatory proteins, ABC transporter proteins, and the enzymes AguA (GH67 {alpha}-glucuronidase), XynA2 (GH10 endoxylanase), and XynB (GH43 β-xylosidase/{alpha}-arabinofuranosidase). Expression of these genes, as well as xynA1 encoding the secreted GH10 endoxylanase, is induced by growth on MeGAXn and repressed by glucose. Sequences in the yesN, lplA, and xynA2 genes within the cluster and in the distal xynA1 gene show significant similarity to catabolite responsive element (cre) defined in Bacillus subtilis for recognition of the catabolite control protein (CcpA) and consequential repression of catabolic regulons. The aldouronate utilization gene cluster in Paenibacillus sp. strain JDR-2 operates as a regulon, coregulated with the expression of xynA1, conferring the ability for efficient assimilation and catabolism of the aldouronate product generated by a multimodular cell surface-anchored GH10 endoxylanase. This cluster offers a desirable metabolic potential for bacterial conversion of hemicellulose fractions of hardwood and crop residues to biobased products.

* Corresponding author. Mailing address: University of Florida, Department of Microbiology and Cell Science, Box 110700, Bldg. 981, Museum Rd., Gainesville, FL 32611. Phone: (352) 392-5923. Fax: (352) 392-5922. E-mail: jpreston{at}ufl.edu

{triangledown} Published ahead of print on 5 October 2007.

Journal of Bacteriology, December 2007, p. 8863-8870, Vol. 189, No. 24
0021-9193/07/$08.00+0     doi:10.1128/JB.01141-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Nong, G., Rice, J. D., Chow, V., Preston, J. F. (2009). Aldouronate Utilization in Paenibacillus sp. Strain JDR-2: Physiological and Enzymatic Evidence for Coupling of Extracellular Depolymerization and Intracellular Metabolism. Appl. Environ. Microbiol. 75: 4410-4418 [Abstract] [Full Text]  


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