Glutamine synthetase sequence evolution in the mycobacteria and their use as molecular markers for Actinobacteria speciation

Hayward, Don; Helden, Paul D. van; Wiid, Ian

doi:10.1186/1471-2148-9-48

Cited by 15 publications

(13 citation statements)

References 54 publications

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“…S2; ref. 23), and GlnR has been shown to regulate their expression (24). We found that two GS enzymes, GSI-β GlnA1 and GSII GlnA4, were directly acetylated in vitro after incubation with AcuA and AcCoA; AcuA did not acetylate GlnA2 or GlnA3 ( Fig.…”

Section: Resultsmentioning

confidence: 74%

“…GSI is largely absent in eukaryotes, but plays a vital role in many microorganisms, existing as α-and β-isoforms that differ in terms of sequence (35-41% identity), regulatory mechanisms (feedback allosteric regulation or adenylylation regulation), and biological functions (catalytic and chaperone activities) (28). Both the GSI-β and GSII enzymes are found in actinomycetes, and are distinguishable from each other by specific 25-amino acid insertion sequences (23). In this study, we found that AcuA-dependent lysine acetylation exerts different effects on four GS enzymes in S. erythraea: inactivation of one GSII enzyme (GlnA4) by acetylation, gain of chaperone activity of one GSI-β (GlnA1) by acetylation, and no acetylation of the other two GSII 6.…”

Section: Discussionmentioning

confidence: 99%

“…GS GlnA1 is present and essential across actinomycetes, exhibiting high sequence similarity (>60%) among homologs (23). The S. erythraea GlnA1 (Sen_GlnA1) sequence was aligned with GSI-β homologs in other species, including SCO2198 from Streptomyces coelicolor, MSMEG_4290 from M. smegmatis, and RV2220 from M. tuberculosis (SI Appendix, Fig.…”

Section: Acetylation Of Gs Enzymes Is Influenced By Extracellular Nitmentioning

confidence: 99%

“…S12B), indicating that the GlnA1 AC -GlnR-DNA interaction is highly conserved across actinomycetes. OmpR-type GlnR proteins have a conserved winged helix-turn-helix motif characterized by three α-helices that recognize and bind similar sequence motifs (23). However, the C-and N-terminal regions of GlnR proteins have low sequence conservation (SI Appendix, Fig.…”

Section: Acetylation Of Gs Enzymes Is Influenced By Extracellular Nitmentioning

confidence: 99%

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Sirtuin-dependent reversible lysine acetylation of glutamine synthetases reveals an autofeedback loop in nitrogen metabolism

You

Yin

et al. 2016

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

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In cells of all domains of life, reversible lysine acetylation modulates the function of proteins involved in central cellular processes such as metabolism. In this study, we demonstrate that the nitrogen regulator GlnR of the actinomycete Saccharopolyspora erythraea directly regulates transcription of the acuA gene (SACE_5148), which encodes a Gcn5-type lysine acetyltransferase. We found that AcuA acetylates two glutamine synthetases (GlnA1 and GlnA4) and that this lysine acetylation inactivated GlnA4 (GSII) but had no significant effect on GlnA1 (GSI-β) activity under the conditions tested. Instead, acetylation of GlnA1 led to a gain-of-function that modulated its interaction with the GlnR regulator and enhanced GlnR–DNA binding. It was observed that this regulatory function of acetylated GSI-β enzymes is highly conserved across actinomycetes. In turn, GlnR controls the catalytic and regulatory activities (intracellular acetylation levels) of glutamine synthetases at the transcriptional and posttranslational levels, indicating an autofeedback loop that regulates nitrogen metabolism in response to environmental change. Thus, this GlnR-mediated acetylation pathway provides a signaling cascade that acts from nutrient sensing to acetylation of proteins to feedback regulation. This work presents significant new insights at the molecular level into the mechanisms underlying the regulation of protein acetylation and nitrogen metabolism in actinomycetes.

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Section: Resultsmentioning

confidence: 74%

Section: Discussionmentioning

confidence: 99%

Section: Acetylation Of Gs Enzymes Is Influenced By Extracellular Nitmentioning

confidence: 99%

Section: Acetylation Of Gs Enzymes Is Influenced By Extracellular Nitmentioning

confidence: 99%

See 2 more Smart Citations

Sirtuin-dependent reversible lysine acetylation of glutamine synthetases reveals an autofeedback loop in nitrogen metabolism

You

Yin

et al. 2016

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

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“…4N2-2 appears to belong to a family of highly conserved bacterial GSs (39). Other bacterial GSs that acetylate fluoroquinolones may also exist, considering that GS is conserved in actinobacteria with high structural homology (21,39) and that N-acetylation activity for norfloxacin is found in several Mycobacterium spp. (15).…”

Section: Discussionmentioning

confidence: 99%

Identification of the Enzyme Responsible forN-Acetylation of Norfloxacin by Microbacterium sp. Strain 4N2-2

Kim

Feng

Chen

et al. 2013

Appl Environ Microbiol

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bMicrobacterium sp. 4N2-2, isolated from a wastewater treatment plant, converts the antibacterial fluoroquinolone norfloxacin to N-acetylnorfloxacin and three other metabolites. Because N-acetylation results in loss of antibacterial activity, identification of the enzyme responsible is important for understanding fluoroquinolone resistance. The enzyme was identified as glutamine synthetase (GS); N-acetylnorfloxacin was produced only under conditions associated with GS expression. The GS gene (glnA) was cloned, and the protein (53 kDa) was heterologously expressed and isolated. Optimal conditions and biochemical properties (K m and V max ) of purified GS were characterized; the purified enzyme was inhibited by Mn 2؉ , Mg 2؉ , ATP, and ADP. The contribution of GS to norfloxacin resistance was shown by using a norfloxacin-sensitive Escherichia coli strain carrying glnA derived from Microbacterium sp. 4N2-2. The GS of Microbacterium sp. 4N2-2 was shown to act as an N-acetyltransferase for norfloxacin, which produced low-level norfloxacin resistance. Structural and docking analysis identified potential binding sites for norfloxacin at the ADP binding site and for acetyl coenzyme A (acetyl-CoA) at a cleft in GS. The results suggest that environmental bacteria whose enzymes modify fluoroquinolones may be able to survive in the presence of low fluoroquinolone concentrations. Fluoroquinolones are widely used as human and veterinary antimicrobial agents (1). Because their persistence in the environment (2) may act as a selective pressure for naïve strains to acquire resistance (3), an understanding of the fate of these drugs should help to prevent drug resistance. The principal resistance mechanisms for fluoroquinolones include the following: (i) mutation of genes for the drug targets (GyrA, GyrB, and ParC) (4-6), (ii) mimicking the drug targets (QnrA, QnrB, and QnrS) (7-9), (iii) reduction of drug accumulation in the cells (AcrAB-TolC and QepA) (4, 10, 11), and (iv) enzymatic modification of the drug [N-acetylation by AAC(6=)-Ib-cr] (12-14).In some strains of Escherichia coli, a mutated aminoglycoside acetyltransferase, AAC(6=)-Ib-cr, acetylates fluoroquinolones at the N-terminal of the piperazine ring (12-14) and enhances bacterial resistance to these drugs (14). Production of N-acetylnorfloxacin and N-nitrosonorfloxacin by environmental Mycobacterium sp. strains has also been found, but the enzymes responsible for modifications are unknown (15) and the aac(6=)-Ib-cr variant gene has not been detected in these strains (12).A norfloxacin-modifying bacterium, Microbacterium sp. strain 4N2-2, was isolated from wastewater (16). Some strains of this genus have been isolated from human clinical specimens, and the majority of them have shown fluoroquinolone resistance (17). Microbacterium sp. 4N2-2 transforms norfloxacin into four different metabolites, including N-acetylnorfloxacin, and cell extracts of this strain catalyze the N-acetylation of norfloxacin (16). NAcetylation is enhanced by Casamino Acids and inhibited by ammo...

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Alkaliphiles and Acidophiles in Nanotechnology

Tiquia-Arashiro

Rodrigues

2016

Extremophiles: Applications in Nanotechnology

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Glutamine synthetase sequence evolution in the mycobacteria and their use as molecular markers for Actinobacteria speciation

Cited by 15 publications

References 54 publications

Sirtuin-dependent reversible lysine acetylation of glutamine synthetases reveals an autofeedback loop in nitrogen metabolism

Sirtuin-dependent reversible lysine acetylation of glutamine synthetases reveals an autofeedback loop in nitrogen metabolism

Identification of the Enzyme Responsible forN-Acetylation of Norfloxacin by Microbacterium sp. Strain 4N2-2

Alkaliphiles and Acidophiles in Nanotechnology

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