Transcription of the glnB and glnA genes in the photosynthetic bacterium Rhodospirillum rubrum

Johansson, Magnus; Nordlund, Stefan

doi:10.1099/13500872-142-5-1265

Cited by 25 publications

(39 citation statements)

References 41 publications

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“…glnB and glnA are organized as a single operon transcribed from the same start site upstream from glnB as determined by lacZ fusion experiments and primer extension analysis. The glnA transcript is more abundant than the glnBA transcript as shown by Northern blotting, suggesting a posttranscriptional processing event, as reported for the regulation of the glnBA operons of Rhodobacter capsulatus (8) and Rhodospirillum rubrum (21). In Rhodobacter capsulatus, a putative stem-loop structure at the 3Ј end of the glnB transcript may be the processing site of an endoribonuclease, allowing rapid turnover of the upstream mRNA.…”

Section: Discussionmentioning

confidence: 77%

Characterization of Azorhizobium caulinodans glnB and glnA genes: involvement of the P(II) protein in symbiotic nitrogen fixation

et al. 1997

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The nucleotide sequence and transcriptional organization of Azorhizobium caulinodans ORS571 glnA, the structural gene for glutamine synthetase (GS), and glnB, the structural gene for the P II protein, have been determined. glnB and glnA are organized as a single operon transcribed from the same start site, under conditions of both nitrogen limitation and nitrogen excess. This start site may be used by two different promoters since the expression of a glnB-lacZ fusion was high in the presence of ammonia and enhanced under conditions of nitrogen limitation in the wild-type strain. The increase was not observed in rpoN or ntrC mutants. In addition, this fusion was overexpressed under both growth conditions, in the glnB mutant strain, suggesting that P II negatively regulates its own expression. A DNA motif, similar to a 54 -dependent promoter consensus, was found in the 5 nontranscribed region. Thus, the glnBA operon seems to be transcribed from a 54 -dependent promoter that operates under conditions of nitrogen limitation and from another uncharacterized promoter in the presence of ammonia. Both glnB and glnBA mutant strains derepress their nitrogenase in the free-living state, but only the glnBA mutant, auxotrophic for glutamine, does not utilize molecular nitrogen for growth. The level of GS adenylylation is not affected in the glnB mutant as compared to that in the wild type. Under symbiotic conditions, the glnB and glnBA mutant strains induced Fix ؊ nodules on Sesbania rostrata roots. P II is the first example in A. caulinodans of a protein required for symbiotic nitrogen fixation but dispensable in bacteria growing in the free-living state.Azorhizobium caulinodans ORS571, isolated from stem nodules of its host plant, the tropical legume Sesbania rostrata, fixes nitrogen both during symbiosis and in the free-living state (15). In the free-living state, this strain assimilates fixed ammonium for growth, via the glutamine synthetase (GS)/glutamate synthetase pathway (14). During symbiosis, ammonium produced by nitrogen fixation is exported from the bacteroid to the vegetal cell, where it is assimilated by the plant GS. As in enteric bacteria, only one GS (GSI) has been characterized in A. caulinodans (14), whereas two forms (GSI and GSII) have been identified in most rhizobia (9). In enteric bacteria and rhizobia, GS activity is modulated by reversible adenylylation in response to changes in the intracellular glutamine/2-ketoglutarate ratio, reflecting the level of cellular nitrogen (20). In Escherichia coli, under conditions of nitrogen limitation, the P II protein, encoded by glnB, is uridylylated by the glnD gene product. Under conditions of nitrogen excess, P II is deuridylylated and activates an adenylyltransferase (28). This enzyme transfers an AMP group to a tyrosine residue in each of the 12 subunits of the GS; the fully adenylylated form of the enzyme is less active (33). The structural gene for GS (glnA) is part of the glnALG operon, where glnL and glnG (also designated ntrB and ntrC) are the structura...

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Section: Discussionmentioning

confidence: 77%

Characterization of Azorhizobium caulinodans glnB and glnA genes: involvement of the P(II) protein in symbiotic nitrogen fixation

et al. 1997

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“…However, glnBp2 activity is enhanced by NtrC in nitrogen-fixing conditions. Although Northern blotting analysis revealed the presence of two transcripts, no glnA promoter was detected, suggesting that the glnA mRNA is produced by processing (34,113). As in Rhodospirillum rubrum and Rhodobacter capsulatus, Azorhizobium caulinaudans glnB and glnA appear to be cotranscribed (158).…”

Section: ␣ Proteobacteriamentioning

confidence: 99%

“…In Rhodospirillum rubrum, glnB and glnA are cotranscribed from a weak 70 -like promoter (glnBp1) and a strong 54 -like promoter (glnBp2) in either nitrogen-rich or nitrogen-fixing conditions (34,113). However, glnBp2 activity is enhanced by NtrC in nitrogen-fixing conditions.…”

Section: ␣ Proteobacteriamentioning

confidence: 99%

“…One gene encodes a P II protein that is very similar to E. coli GlnB and is located upstream of and cotranscribed with glnA (the structural gene for glutamine synthetase I) (7,27,41,94,113,127,151,158,262). The second gene encodes a protein similar to GlnK and is linked to an amtB homologue (125,157,182,185,222,254) (Y. Zhang and G. Roberts, personal communication).…”

Section: ␣ Proteobacteriamentioning

confidence: 99%

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P_IISignal Transduction Proteins, Pivotal Players in Microbial Nitrogen Control

Arcondéguy

Jack

Merrick

2001

Microbiol Mol Biol Rev

395

456

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SUMMARY The PII family of signal transduction proteins are among the most widely distributed signal proteins in the bacterial world. First identified in 1969 as a component of the glutamine synthetase regulatory apparatus, PII proteins have since been recognized as playing a pivotal role in control of prokaryotic nitrogen metabolism. More recently, members of the family have been found in higher plants, where they also potentially play a role in nitrogen control. The PII proteins can function in the regulation of both gene transcription, by modulating the activity of regulatory proteins, and the catalytic activity of enzymes involved in nitrogen metabolism. There is also emerging evidence that they may regulate the activity of proteins required for transport of nitrogen compounds into the cell. In this review we discuss the history of the PII proteins, their structures and biochemistry, and their distribution and functions in prokaryotes. We survey data emerging from bacterial genome sequences and consider other likely or potential targets for control by PII proteins.

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“…The glnB gene is co-transcribed with glnA (the gene encoding GS) (Johansson & Nordlund, 1996), while both glnJ and glnK are linked to genes encoding putative ammonium transporters of the Amt family, amtB1 and amtB2, respectively (Zhang et al, 2006b). It has been shown that an R. rubrum mutant lacking amtB1 has an impaired nitrogenase 'switch-off' response and fails to sequester GlnJ to the membrane (Wang et al, 2005;Zhang et al, 2006b).…”

Section: Introductionmentioning

confidence: 99%

Interaction of the signal transduction protein GlnJ with the cellular targets AmtB1, GlnE and GlnD in Rhodospirillum rubrum: dependence on manganese, 2-oxoglutarate and the ADP/ATP ratio

et al. 2008

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The PII family of signal transduction proteins is widespread amongst the three domains of life, and its members have fundamental roles in the general control of nitrogen metabolism. These proteins exert their regulatory role by direct protein-protein interaction with a multitude of cellular targets. The interactions are dependent on the binding of metabolites such as ATP, ADP and 2-oxoglutarate (2-OG), and on whether or not the PII protein is modified. In the photosynthetic nitrogen-fixing bacterium Rhodospirillum rubrum three PII paralogues have been identified and termed GlnB, GlnJ and GlnK. In this report we analysed the interaction of GlnJ with known cellular targets such as the ammonium transporter AmtB1, the adenylyltransferase GlnE and the uridylyltransferase GlnD. Our results show that the interaction of GlnJ with cellular targets is regulated in vitro by the concentrations of manganese and 2-OG and the ADP : ATP ratio. Furthermore, we show here for the first time, to our knowledge, that in the interactions of GlnJ with the three different partners, the energy signal (ADP : ATP ratio) in fact overrides the carbon/ nitrogen signal (2-OG). In addition, by generating specific amino acid substitutions in GlnJ we show that the interactions with different cellular targets are differentially affected, and the possible implications of these results are discussed. Our results are important to further the understanding of the regulatory role of PII proteins in R. rubrum, a photosynthetic bacterium in which the nitrogen fixation process and its intricate control mechanisms make the regulation of nitrogen metabolism even more complex than in other studied bacteria.

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Transcription of the glnB and glnA genes in the photosynthetic bacterium Rhodospirillum rubrum

Cited by 25 publications

References 41 publications

Characterization of Azorhizobium caulinodans glnB and glnA genes: involvement of the P(II) protein in symbiotic nitrogen fixation

Characterization of Azorhizobium caulinodans glnB and glnA genes: involvement of the P(II) protein in symbiotic nitrogen fixation

P_IISignal Transduction Proteins, Pivotal Players in Microbial Nitrogen Control

Interaction of the signal transduction protein GlnJ with the cellular targets AmtB1, GlnE and GlnD in Rhodospirillum rubrum: dependence on manganese, 2-oxoglutarate and the ADP/ATP ratio

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Transcription of the glnB and glnA genes in the photosynthetic bacterium Rhodospirillum rubrum

Cited by 25 publications

References 41 publications

Characterization of Azorhizobium caulinodans glnB and glnA genes: involvement of the P(II) protein in symbiotic nitrogen fixation

Characterization of Azorhizobium caulinodans glnB and glnA genes: involvement of the P(II) protein in symbiotic nitrogen fixation

PIISignal Transduction Proteins, Pivotal Players in Microbial Nitrogen Control

Interaction of the signal transduction protein GlnJ with the cellular targets AmtB1, GlnE and GlnD in Rhodospirillum rubrum: dependence on manganese, 2-oxoglutarate and the ADP/ATP ratio

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P_IISignal Transduction Proteins, Pivotal Players in Microbial Nitrogen Control