Recent developments on the regulation and structure of glutamine synthetase enzymes from selected bacterial groups

Woods, David R.; Reid, Sharon J.

doi:10.1111/j.1574-6976.1993.tb00001.x

Cited by 46 publications

(13 citation statements)

References 70 publications

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“…The down-regulation of multiple genes encoding ATP-requiring ABC amino acid and polyamine transporters may reflect the inhibition of ATP generation from sulfate respiration and/or the decreased demand for amino acids for protein biosynthesis. In contrast, the up-regulation of the glutamine synthetase gene (glnA) would appear to signal nitrogen-limiting conditions (31,64). It is possible that an increased flux of carbon to support substrate level phosphorylation might overflow into the tricarboxylic acid cycle, altering the ␣-ketoglutarate/glutamine ratio controlling glnA expression.…”

Section: Discussionmentioning

confidence: 99%

Energetic Consequences of Nitrite Stress in Desulfovibrio vulgaris Hildenborough, Inferred from Global Transcriptional Analysis

Huang

et al. 2006

Appl Environ Microbiol

137

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Many of the proteins that are candidates for bioenergetic pathways involved with sulfate respiration in Desulfovibrio spp. have been studied, but complete pathways and overall cell physiology remain to be resolved for many environmentally relevant conditions. In order to understand the metabolism of these microorganisms under adverse environmental conditions for improved bioremediation efforts, Desulfovibrio vulgaris Hildenborough was used as a model organism to study stress response to nitrite, an important intermediate in the nitrogen cycle. Previous physiological studies demonstrated that growth was inhibited by nitrite and that nitrite reduction was observed to be the primary mechanism of detoxification. Global transcriptional profiling with whole-genome microarrays revealed coordinated cascades of responses to nitrite in pathways of energy metabolism, nitrogen metabolism, oxidative stress response, and iron homeostasis. In agreement with previous observations, nitrite-stressed cells showed a decrease in the expression of genes encoding sulfate reduction functions in addition to respiratory oxidative phosphorylation and ATP synthase activity. Consequently, the stressed cells had decreased expression of the genes encoding ATP-dependent amino acid transporters and proteins involved in translation. Other genes up-regulated in response to nitrite include the genes in the Fur regulon, which is suggested to be involved in iron homeostasis, and genes in the Per regulon, which is predicted to be responsible for oxidative stress response.The sulfate-reducing bacteria represent a group of microorganisms characterized by the ability to use sulfate as an electron acceptor in anaerobic respiration (47). Microbial sulfate reduction by these microorganisms is recognized as a widely distributed process of great ecological importance (29,54). Historical interest in sulfate-reducing bacteria has been focused on their involvement in biocorrosion of ferrous metals in the petroleum industry and of concrete structures in wastewater collection systems (15,24). More recent studies (7, 25, 27, 28) have documented the ability of a number of sulfate-reducing bacteria to reduce soluble metal oxyanions to insoluble forms, a process of great potential in the bioremediation of toxic heavy metals and radionuclides such as chromium and uranium (11, 56).To effectively immobilize heavy metals and radionuclides using sulfate-reducing bacteria, it is important to understand the microbial response to adverse environmental factors common in contaminated subsurface environments. One such factor is the high nitrate concentration of many contaminated sites at the nuclear weapon complexes in the United States managed by the Department of Energy (39,49). The presence of nitrate may pose a specific stress to sulfate-reducing bacteria as nitrate has been observed to suppress sulfate reduction activity in situ (9, 21). However, it has been suggested that nitrite, an intermediate that transiently accumulates during nitrate reduction (3,23,58), is directly...

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Section: Discussionmentioning

confidence: 99%

Energetic Consequences of Nitrite Stress in Desulfovibrio vulgaris Hildenborough, Inferred from Global Transcriptional Analysis

Huang

et al. 2006

Appl Environ Microbiol

137

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“…While multiple forms of the GS enzyme have been identi¢ed in di¡erent bacteria [1,5], C. glutamicum harbors GSIL, which is a dodecameric enzyme encoded by the glnA gene. The particular form of GSI found in C. glutamicum is GSIL, since it contains a short stretch of conserved amino acids including a tyrosine residue which is adenylylated, progressively inactivating the enzyme [6].…”

Section: Introductionmentioning

confidence: 99%

Nitrogen and carbon regulation of glutamine synthetase and glutamate synthase in Corynebacterium glutamicum ATCC 13032

Schulz

2001

FEMS Microbiology Letters

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The effect of nitrogen and carbon status on the regulation of glutamine synthetase (GS) and glutamate synthase (GOGAT) were investigated in Corynebacterium glutamicum 13032. Under carbon-sufficient, nitrogen-limiting conditions, GS and GOGAT activities were five-and seven-fold higher, respectively, and transcription of the corresponding genes (glnA and gltBD) was similarly induced. GS activity was also induced in complete medium with added glucose, while GOGAT activity was unaffected. Under carbon-limiting, nitrogen-limiting conditions, the level of GS induction was reduced approximately three-fold, whereas GOGAT activity did not respond. Disruption of the hkm gene, encoding a putative histidine kinase upstream of gltBD, reduced the levels of GOGAT activity two-fold under both nitrogen-rich and nitrogen-limiting conditions. Promoter studies using a hkm^chloramphenicol acetylase fusion plasmid revealed that transcription of hkm is moderately induced (ca. 1.5-fold) by nitrogen starvation, indicating that the Hkm protein may play a role in signal transduction of the nutritional status of the growth medium. ß

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“…Given this importance, one would expect that both the synthesis and the activity of the enzyme would be tightly regulated. Three types of GS, termed GSI to GSIII, are found in prokaryotes; GSI is the typical form found in many organisms (31). In the enterobacteriaceae, GS activity is regulated by an adenylylation/deadenylylation system, the activity of the adenyltransferase itself being regulated by the uridylylation state of the protein P II , which also exterts an effect on the transcription of the glnALG operon through its interaction with the NR II protein (14,23).…”

mentioning

confidence: 99%

ADP-ribosylation of glutamine synthetase in the cyanobacterium Synechocystis sp. strain PCC 6803

1995

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Glutamine synthetase (GS) inactivation was observed in crude cell extracts and in the high-speed supernatant fraction from the cyanobacterium Synechocystis sp. strain PCC 6803 following the addition of ammonium ions, glutamine, or glutamate. Dialysis of the high-speed supernatant resulted in loss of inactivation activity, but this could be restored by the addition of NADH, NADPH, or NADP ؉ and, to a lesser extent, NAD ؉ , suggesting that inactivation of GS involved ADP-ribosylation. This form of modification was confirmed both by labelling experiments using [ P]NAD؉ and by chemical analysis of the hydrolyzed enzyme. Three different forms of GS, exhibiting no activity, biosynthetic activity only, or transferase activity only, could be resolved by chromatography, and the differences in activity were correlated with the extent of the modification. Both biosynthetic and transferase activities were restored to the completely inactive form of GS by treatment with phosphodiesterase.In cyanobacteria, as in most prokaryotes, glutamine synthetase (GS; EC 6.3.1.2) plays a key role in nitrogen assimilation. The enzyme catalyzes the ATP-dependent biosynthesis of glutamine from NH 4 ϩ and glutamate and thus represents a key point for the interaction of carbon and nitrogen metabolism. Given this importance, one would expect that both the synthesis and the activity of the enzyme would be tightly regulated. Three types of GS, termed GSI to GSIII, are found in prokaryotes; GSI is the typical form found in many organisms (31). In the enterobacteriaceae, GS activity is regulated by an adenylylation/deadenylylation system, the activity of the adenyltransferase itself being regulated by the uridylylation state of the protein P II , which also exterts an effect on the transcription of the glnALG operon through its interaction with the NR II protein (14, 23). In gram-positive organisms, GS is not subject to adenylation and activity appears to be regulated by allosteric mechanisms (2).GSs have been purified from a number of cyanobacteria (18) and exhibit the typical size and subunit composition of GSI, although recently the presence of a GSIII has been reported in Synechocystis sp. strain PCC 6803 (24). The regulation of GS activity in cyanobacteria, however, is not well understood. Fisher et al. (4) demonstrated that a cloned cyanobacterial GS was functionally expressed in Escherichia coli but was not subject to adenylation, although cyanobacteria have been shown to possess a P II homolog (28), the activity of which in Synechococcus sp. strain PCC 7942 is regulated by phosphorylation (6). Evidence from several sources (21,25,27,29) suggests that cyanobacterial GS activity is regulated by allosteric processes. In contrast, Joseph and Meeks (9) suggested that GS activity in a symbiotic Nostoc strain might be regulated by a posttranslational mechanism. GS activity has also been shown to be regulated by environmental factors in two unicellular cyanobacteria. Marqués et al. (15) demonstrated a short-term regulation of activity in Synechoc...

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Recent developments on the regulation and structure of glutamine synthetase enzymes from selected bacterial groups

Cited by 46 publications

References 70 publications

Energetic Consequences of Nitrite Stress in Desulfovibrio vulgaris Hildenborough, Inferred from Global Transcriptional Analysis

Energetic Consequences of Nitrite Stress in Desulfovibrio vulgaris Hildenborough, Inferred from Global Transcriptional Analysis

Nitrogen and carbon regulation of glutamine synthetase and glutamate synthase in Corynebacterium glutamicum ATCC 13032

ADP-ribosylation of glutamine synthetase in the cyanobacterium Synechocystis sp. strain PCC 6803

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