Genetic variation of dTDP-l-rhamnose pathway genes in Salmonella enterica The GenBank accession numbers for the sequences reported in this paper are AF279615–AF279625 for the rml gene sets and AF279626–AF279648 for the rmlB gene fragments.

Li, Qun; Reeves, Peter R.

doi:10.1099/00221287-146-9-2291

Cited by 58 publications

(63 citation statements)

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“…ORFs 1, 2, 3, 4, and 16 of the O-antigen cluster were homologous to rmlB, rmlA, rmlC, rmlB, and rmlD of other bacteria, respectively ( Table 2). The products of rmlA through rmlD are responsible for the biosynthesis of dTDP-L-rhamnose from glucose-1-phosphate (24). Rhamnose is a component of surface polysaccharide and is present in many bacterial polysaccharides.…”

Section: Resultsmentioning

confidence: 99%

“…Rhamnose is a component of surface polysaccharide and is present in many bacterial polysaccharides. The four rhamnose synthesis pathway genes are usually found as a block in surface polysaccharide gene clusters, and they are highly conserved throughout all species (24,52). However, the rmlD gene in the A. hydrophila PPD134/91 O-antigen cluster was separated from the other three genes (rmlA through rmlC) of the rhamnose synthesis pathway.…”

Section: Resultsmentioning

confidence: 99%

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NovelAeromonas hydrophilaPPD134/91 Genes Involved in O-Antigen and Capsule Biosynthesis

Zhang¹,

Arakawa

Leung

2002

Infect Immun

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The sequences of the O-antigen and capsule gene clusters of the virulent Aeromonas hydrophila strain PPD134/91 were determined. The O-antigen gene cluster is 17,296 bp long and comprises 17 genes. Seven pathway genes for the synthesis of rhamnose and mannose, six transferase genes, one O unit flippase gene, and one O-antigen chain length determinant gene were identified by amino acid sequence similarity. PCR and Southern blot analysis were performed to survey the distribution of these 17 genes among 11 A. hydrophila strains of different serotypes. A. hydrophila PPD134/91 might belong to serotype O:18, as represented by JCM3980; it contained all the same O-antigen genes as JCM3980 (97 to 100% similarity at the DNA and amino acid levels). The capsule gene cluster of A. hydrophila PPD134/91 is 17,562 bp long and includes 13 genes, which were assembled into three distinct regions similar to those of the group II capsule gene cluster of Escherichia coli and other bacteria. Regions I and III contained four and two capsule transport genes, respectively. Region II had five genes which were highly similar to capsule synthesis pathway genes found in other bacteria. Both the purified O-antigen and capsular polysaccharides increased the ability of the avirulent A. hydrophila strain PPD35/85 to survive in naïve tilapia serum. However, the purified surface polysaccharides had no inhibitory effect on the adhesion of A. hydrophila PPD134/91 to carp epithelial cells.Surface polysaccharides, such as O-antigen and capsule, are important bacterial cell surface components. The O-antigen polysaccharide is covalently ligated to the lipid A-core complex and extends outward from the cell surface. The capsule is an extracellular polysaccharide enclosing the bacterium while remaining attached to the cell. Both the O-antigen polysaccharide and the capsule are composed of repeating oligosaccharide units (44). They act as prominent antigens and play important roles in the pathogenicity of many bacterial pathogens, such as protecting bacterial cells from complement-mediated serum killing (20, 30), acting as adhesion factors (31), protecting the bacteria from the effects of desiccation (38), and aiding survival in phagocytes (56). The serogrouping of bacterial strains within a genus is determined by the structural variability of surface polysaccharides. For example, Escherichia coli strains are divided into more than 160 serogroups based on the different surface polysaccharides (67). Klebsiella species have been classified into 72 serogroups based on the structural variability of their capsular polysaccharides (39).Aeromonas hydrophila is an important pathogen of a wide variety of aquatic and terrestrial animals, especially fish (4). In fish, it causes hemorrhagic septicemia, which often results in high mortalities in commercial aquaculture. Some strains of A. hydrophila are also reported to cause infections in humans. The clinical symptoms include septicemia (17), meningitis (25), peritonitis (35), pneumonia (32), myonecrosis (34), and diarrh...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

NovelAeromonas hydrophilaPPD134/91 Genes Involved in O-Antigen and Capsule Biosynthesis

Zhang¹,

Arakawa

Leung

2002

Infect Immun

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“…The rml genes are always present if rhamnose is in the structure and provide a good basis for determining origins and relationships. We have recently reported on sequence variation of rml genes in S. enterica (Li & Reeves, 2000). All the sequenced S. enterica rml gene sets are located at the 59 end of the O antigen gene cluster, and we observed a strong polarity in the level of sequence similarity and in the nature of variation within rml genes.…”

Section: Introductionmentioning

confidence: 76%

“…We can compare the above situation with that found in O antigen gene clusters of S. enterica (Li & Reeves, 2000), where the rml gene sets are also at the 59 end of the O antigen gene cluster. In this case also the 59 ends of the rml gene sets were generally similar, while genes at the 39 end were generally very different.…”

Section: The Location Of Rml Gene Sets In O Antigen Gene Clustersmentioning

confidence: 99%

The variation of dTDP-l-rhamnose pathway genes in Vibrio cholerae

Hobbs

Reeves

2003

Microbiology

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The genetic variation in the dTDP-L-rhamnose pathway genes (rmlA, rmlB, rmlC and rmlD) in Vibrio cholerae was investigated. The genes are part of the O antigen gene cluster and the aim was to study lateral gene transfer of O antigen gene clusters. The rml genes of an O6 strain were cloned using an Escherichia coli K-12 strain designed for selecting cloned rml genes. Thirty-three strains carrying the known rhamnose-containing O antigens were probed with O6-based rml gene probes, and 19 were positive with from one to all four of the gene probes. Nine rml gene sets from this group were sequenced and found to be in the order rmlBADC, at the 59 end of the gene clusters. A gradient in the level of variation was observed, with highly similar sequences at the 59 end rmlB gene, but very divergent and strain-specific sequences at the 39 end of the rml gene set. The change in level of similarity varied in position, but was always abrupt and coincided with a change in GC content, indicating that the 59 and 39 parts are of different origin, and that recombination within rml genes has occurred. The rml gene sets of two of the strains that did not hybridize with any O6 rml gene probes were also cloned and sequenced. Both gene sets were in the middle of the O antigen gene cluster and were very divergent from each other and all other rml gene sets. This supports the hypothesis that presence of rml genes at the end of the O antigen gene cluster facilitates lateral gene transfer of rml-containing O antigen gene clusters in V. cholerae. The sequence relationships make it possible to identify sites of recombination and to distinguish DNA that has long been in V. cholerae and DNA that probably came into the species with the O antigen gene cluster.

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“…1). The genes (rmlB, rmlC, and rmlD) that encode each of these enzymes have been identified and cloned from numerous bacteria Li and Reeves, 2000).Biosynthesis of rhamnose-nucleotides in plants has only been reported in a few studies in which UDP-a-DGlc was used as the starting material for synthesis of UDP-Rha. As in prokaryotes, UDP-a-D-Glc is converted to UDP-4-keto-6-deoxy-Glc by an enzyme 1 This work was supported in part by the U.S. Department of Agriculture (grant no.…”

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confidence: 99%

A Bifunctional 3,5-Epimerase/4-Keto Reductase for Nucleotide-Rhamnose Synthesis in Arabidopsis

et al. 2004

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L-Rhamnose is a component of plant cell wall pectic polysaccharides, diverse secondary metabolites, and some glycoproteins. The biosynthesis of the activated nucleotide-sugar form(s) of rhamnose utilized by the various rhamnosyltransferases is still elusive, and no plant enzymes involved in their synthesis have been purified. In contrast, two genes (rmlC and rmlD) have been identified in bacteria and shown to encode a 3,5-epimerase and a 4-keto reductase that together convert dTDP-4-keto-6-deoxy-Glc to dTDP-b-L-rhamnose. We have identified an Arabidopsis cDNA that contains domains that share similarity to both reductase and epimerase. The Arabidopsis gene encodes a protein with a predicated molecular mass of approximately 33.5 kD that is transcribed in all tissue examined. The Arabidopsis protein expressed in, and purified from, Escherichia coli converts dTDP-4-keto-6-deoxy-Glc to dTDP-b-L-rhamnose in the presence of NADPH. These results suggest that a single plant enzyme has both the 3,5-epimerase and 4-keto reductase activities. The enzyme has maximum activity between pH 5.5 and 7.5 at 308C. The apparent K m for NADPH is 90 mM and 16.9 mM for dTDP-4-keto-6-deoxy-Glc. The Arabidopsis enzyme can also form UDP-b-L-rhamnose. To our knowledge, this is the first example of a bifunctional plant enzyme involved in sugar nucleotide synthesis where a single polypeptide exhibits the same activities as two separate prokaryotic enzymes.L-Rhamnose is a component of the plant cell wall pectic polysaccharides rhamnogalacturonan I (RG-I) and rhamnogalacturonan II (RG-II; Ridley et al., 2001) and is also present in diverse secondary metabolites including anthocyanins, flavonoids, and triterpenoids (Das et al., 1987;Bar-Peled et al., 1991;van Setten et al., 1995;Shinozaki et al., 1996;Markham et al., 2000), in certain types of plant glycoproteins (Haruko and Haruko, 1999), and in arabinogalactan proteins (Pellerin et al., 1995). The specific enzymes that attach rhamnose to each molecule are known as rhamnosyltransferases (RhaTs). To date, only a small number of RhaTs have been studied, and those were involved in flavonoid rhamnosylation. The characterized RhaTs utilize UDP-b-L-rhamnose (UDP-b-L-Rha) as the donor substrate (Kamsteeg et al., 1978;Feingold, 1982;Bar-Peled et al., 1991), although in mung bean (Vigna radiata), both dTDP-b-L-rhamnose (dTDP-b-L-Rha) and UDP-b-L-Rha were reported to act as sugar donors for the rhamnosylation of flavonoids (Barber and Neufeld, 1961).We are studying the enzymes involved in the synthesis of the nucleotide-rhamnose as part of our effort to understand the synthesis of pectic polysaccharides. To date, the rhamnosylation of plant polysaccharides and glycoproteins has not been studied. Thus, the identity of the activated form(s) of rhamnose needed for the synthesis of these macromolecules is not known with certainty. The enzymes required for the synthesis of the activated form(s) of rhamnose in plants have also not been purified.In contrast, much more is known about the synthesis of rhamnose in...

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Genetic variation of dTDP-l-rhamnose pathway genes in Salmonella enterica The GenBank accession numbers for the sequences reported in this paper are AF279615–AF279625 for the rml gene sets and AF279626–AF279648 for the rmlB gene fragments.

Cited by 58 publications

References 40 publications

NovelAeromonas hydrophilaPPD134/91 Genes Involved in O-Antigen and Capsule Biosynthesis

NovelAeromonas hydrophilaPPD134/91 Genes Involved in O-Antigen and Capsule Biosynthesis

The variation of dTDP-l-rhamnose pathway genes in Vibrio cholerae

A Bifunctional 3,5-Epimerase/4-Keto Reductase for Nucleotide-Rhamnose Synthesis in Arabidopsis

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