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

• Published in: Journal of Bacteriology 1997-04, Vol.179 (7), p.2132-2140
• Main Authors: Kiss, E. (Hungarian Academy of Sciences, Szeged, Hungary.), Reuhs, B.L, Kim, J.S, Kereszt, A, Petrovics, G, Putnoky, P, Dusha, I, Carlson, R.W, Kondorosi, A
• Format: Article
• Language: English
• Subjects: ACILTRANSFERASA; ACYLTRANSFERASE; Acyltransferases - genetics; ALCOHOL DESHIDROGENASA; Alcohol Oxidoreductases - genetics; ALCOOL DESHYDROGENASE; Antigens, Bacterial - chemistry; Antigens, Bacterial - genetics; Aprotinin - genetics; Bacterial Capsules - metabolism; Bacterial Proteins; Bacteriology; Base Sequence; Carrier Proteins - genetics; CHIMIE; COMPOSICION QUIMICA; COMPOSITION CHIMIQUE; Consensus Sequence; DNA Transposable Elements; DNA, Bacterial - genetics; ESPECTROMETRIA; GENE; GENES; Genes, Bacterial; Genetic Complementation Test; IMMUNOLOGIE; INMUNOLOGIA; Magnetic Resonance Spectroscopy; METABOLISME DES GLUCIDES; METABOLISMO DE CARBOHIDRATOS; Molecular Sequence Data; Mutagenesis; MUTANT; MUTANTES; POLISACARIDOS; POLYHOLOSIDE; Polysaccharides, Bacterial - biosynthesis; PROTEINAS AGLUTINANTES; PROTEINE DE LIAISON; QUIMICA; Recombinant Proteins - genetics; Restriction Mapping; RHIZOBIUM MELILOTI; SECUENCIA NUCLEOTIDICA; Sequence Alignment; Sequence Homology, Amino Acid; SEQUENCE NUCLEOTIDIQUE; Sinorhizobium meliloti - genetics; SPECTROMETRIE
• ISSN: 0021-9193; 1098-5530; 1067-8832
• DOI: 10.1128/jb.179.7.2132-2140.1997

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