This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Laus, M. C. Articles by Kijne, J. W. Search for Related Content PubMed PubMed Citation Articles by Laus, M. C. Articles by Kijne, J. W.

Involvement of exo5 in Production of Surface Polysaccharides in Rhizobium leguminosarum and Its Role in Nodulation of Vicia sativa subsp. nigra

Institute of Biology Leiden, Leiden University, Leiden, The Netherlands,¹ Complex Carbohydrate Research Center, The University of Georgia, Athens, Georgia²

Received 20 October 2003/ Accepted 24 May 2004

Analysis of two exopolysaccharide-deficient mutants of Rhizobium leguminosarum, RBL5808 and RBL5812, revealed independent Tn5 transposon integrations in a single gene, designated exo5. As judged from structural and functional homology, this gene encodes a UDP-glucose dehydrogenase responsible for the oxidation of UDP-glucose to UDP-glucuronic acid. A mutation in exo5 affects all glucuronic acid-containing polysaccharides and, consequently, all galacturonic acid-containing polysaccharides. Exo5-deficient rhizobia do not produce extracellular polysaccharide (EPS) or capsular polysaccharide (CPS), both of which contain glucuronic acid. Carbohydrate composition analysis and nuclear magnetic resonance studies demonstrated that EPS and CPS from the parent strain have very similar structures. Lipopolysaccharide (LPS) molecules produced by the mutant strains are deficient in galacturonic acid, which is normally present in the core and lipid A portions of the LPS. The sensitivity of exo5 mutant rhizobia to hydrophobic compounds shows the involvement of the galacturonic acid residues in the outer membrane structure. Nodulation studies with Vicia sativa subsp. nigra showed that exo5 mutant rhizobia are impaired in successful infection thread colonization. This is caused by strong agglutination of EPS-deficient bacteria in the root hair curl. Root infection could be restored by simultaneous inoculation with a Nod factor-defective strain which retained the ability to produce EPS and CPS. However, in this case colonization of the nodule tissue was impaired.

This article has been cited by other articles:

• Kanjilal-Kolar, S., Basu, S. S., Kanipes, M. I., Guan, Z., Garrett, T. A., Raetz, C. R. H. (2006). Expression Cloning of Three Rhizobium leguminosarum Lipopolysaccharide Core Galacturonosyltransferases. J. Biol. Chem. 281: 12865-12878 [Abstract] [Full Text]  
• Carle, A., Hoppner, C., Ahmed Aly, K., Yuan, Q., den Dulk-Ras, A., Vergunst, A., O'Callaghan, D., Baron, C. (2006). The Brucella suis Type IV Secretion System Assembles in the Cell Envelope of the Heterologous Host Agrobacterium tumefaciens and Increases IncQ Plasmid pLS1 Recipient Competence. Infect. Immun. 74: 108-117 [Abstract] [Full Text]