title: The rkpGHI and -J genes are involved in capsular polysaccharide production by Rhizobium meliloti.
abstract: 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.
authors.affiliation: Institute of Genetics, Biological Research Center, Hungarian Academy of Sciences, Szeged.
authors.forename: E
authors.initials: E
authors.lastname: Kiss
authors.forename: B L
authors.initials: BL
authors.lastname: Reuhs
authors.forename: J S
authors.initials: JS
authors.lastname: Kim
authors.forename: A
authors.initials: A
authors.lastname: Kereszt
authors.forename: G
authors.initials: G
authors.lastname: Petrovics
authors.forename: P
authors.initials: P
authors.lastname: Putnoky
authors.forename: I
authors.initials: I
authors.lastname: Dusha
authors.forename: R W
authors.initials: RW
authors.lastname: Carlson
authors.forename: A
authors.initials: A
authors.lastname: Kondorosi
mesh_terms: D000217:Acyltransferases / Q000235:genetics*; D000429:Alcohol Oxidoreductases / Q000235:genetics*; D000942:Antigens, Bacterial / Q000737:chemistry / Q000235:genetics; D007611:Aprotinin / Q000235:genetics*; D016667:Bacterial Capsules / Q000378:metabolism*; D001426:Bacterial Proteins; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics*; D016384:Consensus Sequence; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D047908:Intracellular Signaling Peptides and Proteins; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D016296:Mutagenesis; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D011994:Recombinant Proteins / Q000235:genetics; D015183:Restriction Mapping; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D016962:Sinorhizobium meliloti / Q000235:genetics*
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D002352:Carrier Proteins; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D047908:Intracellular Signaling Peptides and Proteins; D011135:Polysaccharides, Bacterial; D011994:Recombinant Proteins; C105277:RkpJ protein, Rhizobium meliloti; C098973:recombinant Kunitz protease inhibitor; D007611:Aprotinin; D000429:Alcohol Oxidoreductases; C105274:RkpH protein, Rhizobium meliloti; D000217:Acyltransferases; C105276:RkpG protein, Rhizobium meliloti