Pleiotropic effects of mutations that alter the Sinorhizobium meliloti cytochrome c respiratory system

Yurgel, Svetlana N.; Berrocal, Jhoanna G.; Wilson, Cynthia; Kahn, Michael L.

doi:10.1099/mic.0.2006/002634-0

Cited by 18 publications

(21 citation statements)

References 58 publications

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“…While screening S. meliloti Rm1021 transposon insertion mutants for altered phenotypes related to electron transport and carbon metabolism (14), we isolated two mutants with transposon insertions in glnD. glnD insertion mutations have been isolated in other rhizobia (15) but, because Rudnick et al (16) were unable to construct a glnD deletion mutant in S. meliloti and had suggested that glnD was an essential gene, we had not expected to find these mutants.…”

Section: Resultsmentioning

confidence: 99%

“…After overnight mating of Rm1021 with E. coli S17-1 (pSUP5011), transposon insertion mutants were selected on MM-NH4 neomycin medium. Transposon insertions were located using an arbitrary PCR (14) to determine DNA sequences adjacent to the Tn5. Deletion mutants were constructed using an insertion/excision strategy (47).…”

Section: Methodsmentioning

confidence: 99%

“…Alfalfa tests were performed as described previously using Medicago sativa cv. Champ (14). Three to five weeks after inoculation, plants were harvested and examined for root nodule formation, root nodule acetylene and 15 N2 reduction, and shoot dry mass.…”

Section: Methodsmentioning

confidence: 99%

“…Three to five weeks after inoculation, plants were harvested and examined for root nodule formation, root nodule acetylene and 15 N2 reduction, and shoot dry mass. Individual points represent data from at least three boxes containing six plants per box (14); data were from representative experiments, whereby each experiment was done two or more times.…”

Section: Methodsmentioning

confidence: 99%

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A mutant GlnD nitrogen sensor protein leads to a nitrogen-fixing but ineffective Sinorhizobium meliloti symbiosis with alfalfa

Yurgel¹,

Kahn²

2008

Proc. Natl. Acad. Sci. U.S.A.

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The nitrogen-fixing symbiosis between rhizobia and legume plants is a model of coevolved nutritional complementation. The plants reduce atmospheric CO 2 by photosynthesis and provide carbon compounds to symbiotically associated bacteria; the rhizobia use these compounds to reduce (fix) atmospheric N 2 to ammonia, a form of nitrogen the plants can use. A key feature of symbiotic N 2 fixation is that N2 fixation is uncoupled from bacterial nitrogen stress metabolism so that the rhizobia generate ''excess'' ammonia and release this ammonia to the plant. In the symbiosis between Sinorhizobium meliloti and alfalfa, mutations in GlnD, the major bacterial nitrogen stress response sensor protein, led to a symbiosis in which nitrogen was fixed (Fix ؉ ) but was not effective (Eff ؊ ) in substantially increasing plant growth. Fixed 15 N2 was transported to the shoots, but most fixed 15 N was not present in the plant after 24 h. Analysis of free-living S. meliloti strains with mutations in genes related to nitrogen stress response regulation (glnD, glnB, ntrC, and ntrA) showed that catabolism of various nitrogen-containing compounds depended on the NtrC and GlnD components of the nitrogen stress response cascade. However, only mutants of GlnD with an amino terminal deletion had the unusual Fix ؉ Eff ؊ symbiotic phenotype, and the data suggest that these glnD mutants export fixed nitrogen in a form that the plants cannot use. These results indicate that bacterial nitrogen stress regulation is important to symbiotic productivity and suggest that GlnD may act in a novel way to influence symbiotic behavior.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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A mutant GlnD nitrogen sensor protein leads to a nitrogen-fixing but ineffective Sinorhizobium meliloti symbiosis with alfalfa

Yurgel¹,

Kahn²

2008

Proc. Natl. Acad. Sci. U.S.A.

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“…Champ) was used for all nodulation studies. The plant tests were performed as described previously (46). Four to five weeks after inoculation, plants were harvested; shoot dry mass and root nodule formation were examined.…”

Section: Figmentioning

confidence: 99%

GlnB/GlnK PII Proteins and Regulation of the Sinorhizobium meliloti Rm1021 Nitrogen Stress Response and Symbiotic Function

et al. 2010

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The Sinorhizobium meliloti Rm1021⌬glnD-sm2 mutant, which is predicted to make a GlnD nitrogen sensor protein truncated at its amino terminus, fixes nitrogen in symbiosis with alfalfa, but the plants cannot use this nitrogen for growth (S. N. Yurgel and M. L. Kahn, Proc. Natl. Acad. Sci. U. S. A. 105:18958-18963, 2008). The mutant also has a generalized nitrogen stress response (NSR) defect. These results suggest a connection between GlnD, symbiotic metabolism, and the NSR, but the nature of this connection is unknown. In many bacteria, GlnD modifies the PII proteins, GlnB and GlnK, as it transduces a measurement of bacterial nitrogen status to a cellular response. We have now constructed and analyzed Rm1021 mutants missing GlnB, GlnK, or both proteins. Rm1021⌬glnK⌬glnB was much more defective in its NSR than either single mutant, suggesting that GlnB and GlnK overlap in regulating the NSR in free-living Rm1021. The single mutants and the double mutant all formed an effective symbiosis, indicating that symbiotic nitrogen exchange could occur without the need for either GlnB or GlnK. N-terminal truncation of the GlnD protein interfered with PII protein modification in vitro, suggesting either that unmodified PII proteins were responsible for the glnD mutant's ineffective phenotype or that connecting GlnD and appropriate symbiotic behavior does not require the PII proteins.

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Truncated betB2-144 plays a critical role in Sinorhizobium meliloti Rm2011 osmoprotection and glycine-betaine catabolism

Yurgel¹,

Rice²,

Mulder³

et al. 2013

European Journal of Soil Biology

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Pleiotropic effects of mutations that alter the Sinorhizobium meliloti cytochrome c respiratory system

Cited by 18 publications

References 58 publications

A mutant GlnD nitrogen sensor protein leads to a nitrogen-fixing but ineffective Sinorhizobium meliloti symbiosis with alfalfa

A mutant GlnD nitrogen sensor protein leads to a nitrogen-fixing but ineffective Sinorhizobium meliloti symbiosis with alfalfa

GlnB/GlnK PII Proteins and Regulation of the Sinorhizobium meliloti Rm1021 Nitrogen Stress Response and Symbiotic Function

Truncated betB2-144 plays a critical role in Sinorhizobium meliloti Rm2011 osmoprotection and glycine-betaine catabolism

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