Nucleotide sequence and predicted functions of the entire
            <i>Sinorhizobium meliloti</i>
            pSymA megaplasmid

Barnett, Melanie J.; Fisher, Robert F.; Jones, Thomas A.; Komp, Caridad; Abola, A. Pia; Barloy-Hubler, Frédérique; Bowser, Leah; Capela, Delphine; Galibert, Francis; Gouzy, Jérôme; Gurjal, Mani; Hong, Andrea; Huizar, Lucas; Hyman, Richard W.; Kahn, Daniel; Kahn, Michael L.; Kalman, Sumner M.; Keating, David H.; Palm, Curtis J.; Peck, Melicent C.; Surzycki, Raymond; Wells, Derek H.; Yeh, Kuo‐Chen; Davis, Ronald W.; Federspiel, Nancy A.; Long, Sharon R.

doi:10.1073/pnas.161294798

Cited by 281 publications

(241 citation statements)

References 72 publications

(62 reference statements)

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“…Although presumably involved in inducing conjugative horizontal DNA transfer, very little data currently exist regarding the functional role of the plasmid-encoded T4SS in rhizobia. Stiens et al (2006) however reported that the T4SS on pSmeSM11a from S. meliloti was not involved in mobilization of this plasmid, and S. meliloti strains containing virB operon deletions were not affected in nodulation or symbiotic nitrogen fixation (Barnett et al, 2001).…”

Section: Conjugation and Gene Transfer Systemsmentioning

confidence: 99%

“…The repABC replicon family is required for ensuring proper segregation and efficient maintenance of low-copy DNA replicons (Ramirez-Romero et al, 2000), and has been extensively characterized and is genetically conserved in the a-proteobacteria. The repABC replicon Barnett et al, 2001), the Ti plasmids in Agrobacterium sp. strains (Li and Farrand, 2000) and the second chromosome in the animal pathogen Brucella (Paulsen et al, 2002).…”

Section: The Repabc Replicon Of Plasmid Pbtai1mentioning

confidence: 99%

“…Plasmids can vary significantly between and within species of rhizobia, ranging from 180 kb in Rhizobium leguminosarum bv. trifolii, to 1.35 Mb in Sinorhizobium meliloti (Mercado-Blanco and Toro, 1996;Barnett et al, 2001). In contrast, genes encoding nod factors and nitrogenase in Bradyrhizobium species and most mesorhizobia are located on the chromosome in regions termed 'symbiosis islands' (Sawada et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

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Insights learned from pBTAi1, a 229-kb accessory plasmid from Bradyrhizobium sp. strain BTAi1 and prevalence of accessory plasmids in other Bradyrhizobium sp. strains

et al. 2008

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In silico, physiological and in planta analyses were used to characterize pBTAi1, a 229-kb accessory plasmid from Bradyrhizobium sp. strain BTAi1, and assess its potential ecological function under free-living and symbiotic growth conditions. Sequence analysis revealed the presence of an uptake hydrogenase system, a repABC family plasmid replication module and open reading frames encoding type IV secretion system, TraI and TraR autoinducer proteins and several copper resistance-related proteins. Bradyrhizobium sp. BTAi1 was capable of growing in 200 mg l À1 CuCl 2 . In contrast, the closely related, plasmid-free Bradyrhizobium sp. strain ORS278 could not grow at copper concentrations exceeding 100 mg l À1 . The plasmid-localized hydrogenase genes were phylogenetically distinct from those typically found in other rhizobial species, and were most related to hup genes from Thiobacillus denitrificans. The induction of the plasmid-borne hydrogenase genes during symbiosis was significantly lower than the two chromosomal-borne hydrogenase clusters. CHEF-pulsed-field gel electrophoresis was used for a comprehensive analysis of the diversity, abundance and genetic composition of accessory plasmids in other Bradyrhizobium strains. Plasmids were detected in 11 of 46 (23.9%) geographically diverse Bradyrhizobium japonicum and Bradyrhizobium elkanii strains, isolated from the United States, China and Thailand. Plasmid size was heterogeneous, ranging from 75 to 330 kb, with only two strains (DASA01244 and DASA01265) harboring plasmids with identical (240 kb) size. None of the plasmids harbored nodulation or hydrogenase genes. Taken together, our results indicate that while plasmids having ecologically significant functions may be detected in Bradyrhizobium sp. strains, they lack genes necessary for symbioses with legumes.

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Section: Conjugation and Gene Transfer Systemsmentioning

confidence: 99%

Section: The Repabc Replicon Of Plasmid Pbtai1mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Insights learned from pBTAi1, a 229-kb accessory plasmid from Bradyrhizobium sp. strain BTAi1 and prevalence of accessory plasmids in other Bradyrhizobium sp. strains

et al. 2008

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“…S. meliloti has three circular replicons: a chromosome (3.65 Mb) that encodes most of the housekeeping and essential genes (10) and two megaplasmids, pSymA (1.4 Mb) and pSymB (1.7 Mb) (11). pSymA is not essential for viability but contains many of the genes required for symbiosis [nod, nif, and most fix genes (12,13)]. pSymB contains exo and dct genes required for symbiosis, as well as several genes essential for viability (14).…”

mentioning

confidence: 99%

A dual-genome Symbiosis Chip for coordinate study of signal exchange and development in a prokaryote–host interaction

Barnett

Toman

Fisher

et al. 2004

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

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277

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The soil-dwelling ␣-proteobacterium Sinorhizobium meliloti engages in a symbiosis with legumes: S. meliloti elicits the formation of plant root nodules where it converts dinitrogen to ammonia for use by the plant in exchange for plant photosynthate. To study the coordinate differentiation of S. meliloti and its legume partner during nodule development, we designed a custom Affymetrix GeneChip with the complete S. meliloti genome and Ϸ10,000 probe sets for the plant host, Medicago truncatula. Expression profiling of free-living S. meliloti grown with the plant signal molecule luteolin in defined minimal and rich media or of strains altered in the expression of key regulatory proteins (NodD1, NodD3, and RpoN) confirms previous data and identifies previously undescribed regulatory targets. Analyses of root nodules show that this Symbiosis Chip allows the study of gene expression in both partners simultaneously. Our studies detail nearly 5,000 transcriptome changes in symbiosis and document complex transcriptional profiles of S. meliloti in different environments.expression ͉ Medicago ͉ microarray ͉ Sinorhizobium meliloti

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“…1) contains both ArgE and ArgJ (Dunn, 2015), which are non-homologous isofunctional enzymes, rather than isoforms derived from a common ancestral form (Omelchenko et al, 2010). Because ArgE is the only enzyme of the predicted pathway encoded on a megaplasmid, it was suggested to have an ancillary role in ornithine production (Barnett et al, 2001). ArgJ is annotated as a bifunctional enzyme in the S. meliloti genome sequence and would thus synthesize NAG de novo as well as deacetylate NAO.…”

Section: Introductionmentioning

confidence: 99%

Genetic and biochemical characterization of arginine biosynthesis in Sinorhizobium meliloti 1021

et al. 2015

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L-Ornithine production in the alfalfa microsymbiont Sinorhizobium meliloti occurs as an intermediate step in arginine biosynthesis. Ornithine is required for effective symbiosis but its synthesis in S. meliloti has been little studied. Unlike most bacteria, S. meliloti 1021 is annotated as encoding two enzymes producing ornithine: N-acetylornithine (NAO) deacetylase (ArgE) hydrolyses NAO to acetate and ornithine, and glutamate N-acetyltransferase (ArgJ) transacetylates L-glutamate with the acetyl group from NAO, forming ornithine and N-acetylglutamate (NAG). NAG is the substrate for the second step of arginine biosynthesis catalysed by NAG kinase (ArgB). Inactivation of argB in strain 1021 resulted in arginine auxotrophy. The activity of purified ArgB was significantly inhibited by arginine but not by ornithine. The purified ArgJ was highly active in NAO deacetylation/glutamate transacetylation and was significantly inhibited by ornithine but not by arginine. The purified ArgE protein (with a 6His-Sumo affinity tag) was also active in deacetylating NAO. argE and argJ single mutants, and an argEJ double mutant, are arginine prototrophs. Extracts of the double mutant contained aminoacylase (Ama) activity that deacetylated NAO to form ornithine. The purified products of three candidate ama genes (smc00682 (hipO1), smc02256 (hipO2) and smb21279) all possessed NAO deacetylase activity. hipO1 and hipO2, but not smb21279, expressed in trans functionally complemented an Escherichia coli DargE : : Km mutant. We conclude that Ama activity accounts for the arginine prototrophy of the argEJ mutant. Transcriptional assays of argB, argE and argJ, fused to a promoterless gusA gene, showed that their expression was not significantly affected by exogenous arginine or ornithine.

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Nucleotide sequence and predicted functions of the entire Sinorhizobium meliloti pSymA megaplasmid

Cited by 281 publications

References 72 publications

Insights learned from pBTAi1, a 229-kb accessory plasmid from Bradyrhizobium sp. strain BTAi1 and prevalence of accessory plasmids in other Bradyrhizobium sp. strains

Insights learned from pBTAi1, a 229-kb accessory plasmid from Bradyrhizobium sp. strain BTAi1 and prevalence of accessory plasmids in other Bradyrhizobium sp. strains

A dual-genome Symbiosis Chip for coordinate study of signal exchange and development in a prokaryote–host interaction

Genetic and biochemical characterization of arginine biosynthesis in Sinorhizobium meliloti 1021

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