Genetic analysis and regulation of the Rhizobium meliloti genes controlling C4-dicarboxylic acid transport

Wang, Yi‐Ping; Birkenhead, K.; Boesten, Bert; Manian, Sundaram S.; O’Gara, Fergal

doi:10.1016/0378-1119(89)90473-3

Cited by 62 publications

(35 citation statements)

References 22 publications

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“…These data were calculated as Miller units using the following formula: (A 420 ϫ 1,000)/(OD 600 ϫ time ϫ dilution). Reporter gene expression was also measured in the bacteroid state as described by Wang et al (49). In brief, 10 to 15 nodules were harvested at 4 weeks postinoculation and crushed in a buffer containing 1 ml of 0.25 M mannitol and 0.05 M Tris-HCl (pH 7.5).…”

Section: Methodsmentioning

confidence: 99%

Characterization of a Gene Family of Outer Membrane Proteins ( ropB ) in Rhizobium leguminosarum bv. viciae VF39SM and the Role of the Sensor Kinase ChvG in Their Regulation

et al. 2010

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The outer membrane of Gram-negative bacteria represents the interface between the bacterium and its external environment. It has a critical role as a protective barrier against harmful substances and is also important in host-bacteria interactions representing the initial physical point of contact between the host cell and bacterial cell. RopB is a previously identified outer membrane protein from Rhizobium leguminosarum bv. viciae that is present in free-living cells but absent in bacteroids (H. P. Roest, I. H. Mulders, C. A. Wijffelman, and B. J. Lugtenberg, Mol. Plant Microbe Interact. 8:576-583, 1995). The functions of RopB and the molecular mechanisms of ropB gene regulation have remained unknown. We identified and cloned ropB and two homologs (ropB2 and ropB3) from the R. leguminosarum VF39SM genome. Reporter gene fusions indicated that the expression of ropB was 8-fold higher when cells were grown in complex media than when they were grown in minimal media, while ropB3 expression was constitutively expressed at low levels in both complex and minimal media. Expression of ropB2 was negligible under all conditions tested. The use of minimal media supplemented with various sources of peptides resulted in a 5-fold increase in ropB expression. An increase in ropB expression in the presence of peptides was not observed in a chvG mutant background, indicating a role for the sensor kinase in regulating ropB expression. Each member of the ropB gene family was mutated using insertional mutagenesis, and the mutants were assayed for susceptibility to antimicrobial agents and symbiotic phenotypes. All mutants formed effective nodules on pea plants, and gene expression for each rop gene in bacteroids was negligible. The functions of ropB2 and ropB3 remain cryptic, while the ropB mutant had an increased sensitivity to detergents, hydrophobic antibiotics, and weak organic acids, suggesting a role for RopB in outer membrane stability.

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Section: Methodsmentioning

confidence: 99%

Characterization of a Gene Family of Outer Membrane Proteins ( ropB ) in Rhizobium leguminosarum bv. viciae VF39SM and the Role of the Sensor Kinase ChvG in Their Regulation

et al. 2010

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“…The other is encoded by the dctA gene of rhizobia and is embedded in the inner membrane of the bacteroid (250,422). In free-living rhizobia, transcription of dctA is activated by dicarboxylic acids via the DctB-DctD two-component system (164,517). DctB was proposed to sense the presence of dicarboxylic acids in the periplasm and to phosphorylate DctD in a signal-dependent manner.…”

Section: Regulation Of Symbiotic Nitrogen Fixationmentioning

confidence: 99%

Detection of and Response to Signals Involved in Host-Microbe Interactions by Plant-Associated Bacteria

Brencic

Winans

2005

Microbiol Mol Biol Rev

337

208

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Diverse interactions between hosts and microbes are initiated by the detection of host-released chemical signals. Detection of these signals leads to altered patterns of gene expression that culminate in specific and adaptive changes in bacterial physiology that are required for these associations. This concept was first demonstrated for the members of the family Rhizobiaceae and was later found to apply to many other plant-associated bacteria as well as to microbes that colonize human and animal hosts. The family Rhizobiaceae includes various genera of rhizobia as well as species of Agrobacterium. Rhizobia are symbionts of legumes, which fix nitrogen within root nodules, while Agrobacterium tumefaciens is a pathogen that causes crown gall tumors on a wide variety of plants. The plant-released signals that are recognized by these bacteria are low-molecular-weight, diffusible molecules and are detected by the bacteria through specific receptor proteins. Similar phenomena are observed with other plant pathogens, including Pseudomonas syringae, Ralstonia solanacearum, and Erwinia spp., although here the signals and signal receptors are not as well defined. In some cases, nutritional conditions such as iron limitation or the lack of nitrogen sources seem to provide a significant cue. While much has been learned about the process of host detection over the past 20 years, our knowledge is far from being complete. The complex nature of the plant-microbe interactions makes it extremely challenging to gain a comprehensive picture of host detection in natural environments, and thus many signals and signal recognition systems remain to be described

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“…One of the first reports of catabolite repression in S. meliloti (then Rhizobium meliloti) showed that S. meliloti exhibited diauxic growth in a medium containing 0.2% succinate and 0.2% lactose as carbon sources (63). This study also showed that the production of ␤-galactosidase was repressed when succinate and lactose were present together and that it increased to higher levels after succinate had been exhausted from the medium.Succinate and other C 4 -dicarboxylic acids are sensed and transported by the Dct (dicarboxylate transport) system which is encoded by dctA, dctB, and dctD (48,66,(69)(70)(71). DctB is activated by the presence of C 4 -dicarboxylic acids and autophosphorylates.…”

mentioning

confidence: 99%

“…Succinate and other C 4 -dicarboxylic acids are sensed and transported by the Dct (dicarboxylate transport) system which is encoded by dctA, dctB, and dctD (48,66,(69)(70)(71). DctB is activated by the presence of C 4 -dicarboxylic acids and autophosphorylates.…”

mentioning

confidence: 99%

Characterization of a Two-Component Regulatory System That Regulates Succinate-Mediated Catabolite Repression in Sinorhizobium meliloti

et al. 2010

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When they are available, Sinorhizobium meliloti utilizes C 4 -dicarboxylic acids as preferred carbon sources for growth while suppressing the utilization of some secondary carbon sources such as ␣-and ␤-galactosides. The phenomenon of using succinate as the sole carbon source in the presence of secondary carbon sources is termed succinate-mediated catabolite repression (SMCR). Genetic screening identified the gene sma0113 as needed for strong SMCR when S. meliloti was grown in succinate plus lactose, maltose, or raffinose. sma0113 and the gene immediately downstream, sma0114, encode the proteins Sma0113, an HWE histidine kinase with five PAS domains, and Sma0114, a CheY-like response regulator lacking a DNA-binding domain. sma0113 in-frame deletion mutants show a relief of catabolite repression compared to the wild type. sma0114 in-frame deletion mutants overproduce polyhydroxybutyrate (PHB), and this overproduction requires sma0113. Sma0113 may use its five PAS domains for redox level or energy state monitoring and use that information to regulate catabolite repression and related responses.Sinorhizobium, Rhizobium, Bradyrhizobium, and Azorhizobium (rhizobia) are important nitrogen-fixing prokaryotes. These grow in the soil as free-living organisms but can also live as nitrogen-fixing symbionts inside roots of plants belonging to the family Leguminosae (8,11,21,33,41,54). Rhizobia are able to utilize a wide range of compounds as carbon sources, such as sugars, amino acids, and tricarboxylic acid (TCA) cycle intermediates. Studies have shown that the C 4 -dicarboxylic TCA cycle intermediates succinate, fumarate, and malate support high rates of growth in laboratory medium and are used by rhizobia in preference to carbon sources including glucose, fructose, galactose, lactose, and myo-inositol (23,26,44,63).The phenomenon of Sinorhizobium meliloti utilizing succinate and similar C 4 -dicarboxylic acids in preference to other compounds is called succinate-mediated catabolite repression (SMCR) (9). One of the first reports of catabolite repression in S. meliloti (then Rhizobium meliloti) showed that S. meliloti exhibited diauxic growth in a medium containing 0.2% succinate and 0.2% lactose as carbon sources (63). This study also showed that the production of ␤-galactosidase was repressed when succinate and lactose were present together and that it increased to higher levels after succinate had been exhausted from the medium.Succinate and other C 4 -dicarboxylic acids are sensed and transported by the Dct (dicarboxylate transport) system which is encoded by dctA, dctB, and dctD (48,66,(69)(70)(71). DctB is activated by the presence of C 4 -dicarboxylic acids and autophosphorylates. Activated DctB phosphorylates DctD, which then binds upstream of dctA along with 54 -RNA polymerase to initiate transcription (70). dctA encodes the permease required for transport of succinate and other C 4 -dicarboxylic acids. When succinate is in abundance, S. meliloti will preferentially import this carbon source for metabolism and in...

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Genetic analysis and regulation of the Rhizobium meliloti genes controlling C4-dicarboxylic acid transport

Cited by 62 publications

References 22 publications

Characterization of a Gene Family of Outer Membrane Proteins ( ropB ) in Rhizobium leguminosarum bv. viciae VF39SM and the Role of the Sensor Kinase ChvG in Their Regulation

Characterization of a Gene Family of Outer Membrane Proteins ( ropB ) in Rhizobium leguminosarum bv. viciae VF39SM and the Role of the Sensor Kinase ChvG in Their Regulation

Detection of and Response to Signals Involved in Host-Microbe Interactions by Plant-Associated Bacteria

Characterization of a Two-Component Regulatory System That Regulates Succinate-Mediated Catabolite Repression in Sinorhizobium meliloti

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