Logo of jbacterPermissionsJournals.ASM.orgJournalJB ArticleJournal InfoAuthorsReviewers
J Bacteriol. 1997 Apr; 179(7): 2132–2140.
PMCID: PMC178947

The rkpGHI and -J genes are involved in capsular polysaccharide production by Rhizobium meliloti.


The first complementation unit of the fix-23 region of Rhizobium meliloti, which comprises six genes (rkpAB-CDEF) exhibiting similarity to fatty acid synthase genes, is required for the production of a novel type of capsular polysaccharide that is involved in root nodule development and structurally analogous to group II K antigens found in Escherichia coli (G. Petrovics, P. Putnoky, R. Reuhs, J. Kim, T. A. Thorp, K. D. Noel, R. W. Carlson, and A. Kondorosi, Mol. Microbiol. 8:1083-1094, 1993; B. L. Reuhs, R. W. Carlson, and J. S. Kim, J. Bacteriol. 175:3570-3580, 1993). Here we present the nucleotide sequence for the other three complementation units of the fix-23 locus, revealing the presence of four additional open reading frames assigned to genes rkpGHI and -J. The putative RkpG protein shares similarity with acyltransferases, RkpH is homologous to short-chain alcohol dehydrogenases, and RkpJ shows significant sequence identity with bacterial polysaccharide transport proteins, such as KpsS of E. coli. No significant homology was found for RkpI. Biochemical and immunological analysis of Tn5 derivatives for each gene demonstrated partial or complete loss of capsular polysaccharides from the cell surface; on this basis, we suggest that all genes in the fix-23 region are required for K-antigen synthesis or transport.

Full Text

The Full Text of this article is available as a PDF (1.4M).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Altschul SF, Gish W, Miller W, Myers EW, Lipman DJ. Basic local alignment search tool. J Mol Biol. 1990 Oct 5;215(3):403–410. [PubMed]
  • Argos P, Rao JK. Prediction of protein structure. Methods Enzymol. 1986;130:185–207. [PubMed]
  • Bánfalvi Z, Sakanyan V, Koncz C, Kiss A, Dusha I, Kondorosi A. Location of nodulation and nitrogen fixation genes on a high molecular weight plasmid of R. meliloti. Mol Gen Genet. 1981;184(2):318–325. [PubMed]
  • Boulnois GJ, Roberts IS, Hodge R, Hardy KR, Jann KB, Timmis KN. Analysis of the K1 capsule biosynthesis genes of Escherichia coli: definition of three functional regions for capsule production. Mol Gen Genet. 1987 Jun;208(1-2):242–246. [PubMed]
  • Bronner D, Sieberth V, Pazzani C, Roberts IS, Boulnois GJ, Jann B, Jann K. Expression of the capsular K5 polysaccharide of Escherichia coli: biochemical and electron microscopic analyses of mutants with defects in region 1 of the K5 gene cluster. J Bacteriol. 1993 Sep;175(18):5984–5992. [PMC free article] [PubMed]
  • Cross AS. The biologic significance of bacterial encapsulation. Curr Top Microbiol Immunol. 1990;150:87–95. [PubMed]
  • Devereux J, Haeberli P, Smithies O. A comprehensive set of sequence analysis programs for the VAX. Nucleic Acids Res. 1984 Jan 11;12(1 Pt 1):387–395. [PMC free article] [PubMed]
  • Franssen HJ, Vijn I, Yang WC, Bisseling T. Developmental aspects of the Rhizobium-legume symbiosis. Plant Mol Biol. 1992 May;19(1):89–107. [PubMed]
  • Frosch M, Edwards U, Bousset K, Krausse B, Weisgerber C. Evidence for a common molecular origin of the capsule gene loci in gram-negative bacteria expressing group II capsular polysaccharides. Mol Microbiol. 1991 May;5(5):1251–1263. [PubMed]
  • Frosch M, Müller A. Phospholipid substitution of capsular polysaccharides and mechanisms of capsule formation in Neisseria meningitidis. Mol Microbiol. 1993 May;8(3):483–493. [PubMed]
  • Fuhrmann J, Wollum AG. Simplified Enzyme-Linked Immunosorbent Assay for Routine Identification of Rhizobium japonicum Antigens. Appl Environ Microbiol. 1985 Apr;49(4):1010–1013. [PMC free article] [PubMed]
  • Jörnvall H, von Bahr-Lindström H, Jeffery J. Extensive variations and basic features in the alcohol dehydrogenase-sorbitol dehydrogenase family. Eur J Biochem. 1984 Apr 2;140(1):17–23. [PubMed]
  • Kannenberg EL, Brewin NJ. Host-plant invasion by Rhizobium: the role of cell-surface components. Trends Microbiol. 1994 Aug;2(8):277–283. [PubMed]
  • Kroll JS, Zamze S, Loynds B, Moxon ER. Common organization of chromosomal loci for production of different capsular polysaccharides in Haemophilus influenzae. J Bacteriol. 1989 Jun;171(6):3343–3347. [PMC free article] [PubMed]
  • Leigh JA, Coplin DL. Exopolysaccharides in plant-bacterial interactions. Annu Rev Microbiol. 1992;46:307–346. [PubMed]
  • Pazzani C, Rosenow C, Boulnois GJ, Bronner D, Jann K, Roberts IS. Molecular analysis of region 1 of the Escherichia coli K5 antigen gene cluster: a region encoding proteins involved in cell surface expression of capsular polysaccharide. J Bacteriol. 1993 Sep;175(18):5978–5983. [PMC free article] [PubMed]
  • Persson B, Krook M, Jörnvall H. Characteristics of short-chain alcohol dehydrogenases and related enzymes. Eur J Biochem. 1991 Sep 1;200(2):537–543. [PubMed]
  • Petrovics G, Putnoky P, Reuhs B, Kim J, Thorp TA, Noel KD, Carlson RW, Kondorosi A. The presence of a novel type of surface polysaccharide in Rhizobium meliloti requires a new fatty acid synthase-like gene cluster involved in symbiotic nodule development. Mol Microbiol. 1993 Jun;8(6):1083–1094. [PubMed]
  • Putnoky P, Kondorosi A. Two gene clusters of Rhizobium meliloti code for early essential nodulation functions and a third influences nodulation efficiency. J Bacteriol. 1986 Sep;167(3):881–887. [PMC free article] [PubMed]
  • Putnoky P, Petrovics G, Kereszt A, Grosskopf E, Ha DT, Bánfalvi Z, Kondorosi A. Rhizobium meliloti lipopolysaccharide and exopolysaccharide can have the same function in the plant-bacterium interaction. J Bacteriol. 1990 Sep;172(9):5450–5458. [PMC free article] [PubMed]
  • Reuhs BL, Carlson RW, Kim JS. Rhizobium fredii and Rhizobium meliloti produce 3-deoxy-D-manno-2-octulosonic acid-containing polysaccharides that are structurally analogous to group II K antigens (capsular polysaccharides) found in Escherichia coli. J Bacteriol. 1993 Jun;175(11):3570–3580. [PMC free article] [PubMed]
  • Reuhs BL, Williams MN, Kim JS, Carlson RW, Côté F. Suppression of the Fix- phenotype of Rhizobium meliloti exoB mutants by lpsZ is correlated to a modified expression of the K polysaccharide. J Bacteriol. 1995 Aug;177(15):4289–4296. [PMC free article] [PubMed]
  • Rimokh R, Gadoux M, Berthéas MF, Berger F, Garoscio M, Deléage G, Germain D, Magaud JP. FVT-1, a novel human transcription unit affected by variant translocation t(2;18)(p11;q21) of follicular lymphoma. Blood. 1993 Jan 1;81(1):136–142. [PubMed]
  • Roberts IS, Mountford R, Hodge R, Jann KB, Boulnois GJ. Common organization of gene clusters for production of different capsular polysaccharides (K antigens) in Escherichia coli. J Bacteriol. 1988 Mar;170(3):1305–1310. [PMC free article] [PubMed]
  • Sanger F, Nicklen S, Coulson AR. DNA sequencing with chain-terminating inhibitors. Proc Natl Acad Sci U S A. 1977 Dec;74(12):5463–5467. [PMC free article] [PubMed]
  • Williams MN, Hollingsworth RI, Klein S, Signer ER. The symbiotic defect of Rhizobium meliloti exopolysaccharide mutants is suppressed by lpsZ+, a gene involved in lipopolysaccharide biosynthesis. J Bacteriol. 1990 May;172(5):2622–2632. [PMC free article] [PubMed]
  • Yanisch-Perron C, Vieira J, Messing J. Improved M13 phage cloning vectors and host strains: nucleotide sequences of the M13mp18 and pUC19 vectors. Gene. 1985;33(1):103–119. [PubMed]

Articles from Journal of Bacteriology are provided here courtesy of American Society for Microbiology (ASM)


Related citations in PubMed

See reviews...See all...

Cited by other articles in PMC

See all...


Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...