Isolation of an ammonium or methylammonium ion transport mutant of Escherichia coli and complementation by the cloned gene

Jayakumar, Arumugam; Hwang, Shao-Ying; Fabiny, J M; Chinault, A. Craig; Barnes, Eugene M.

doi:10.1128/jb.171.2.996-1001.1989

Cited by 28 publications

(53 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The B. subtilis nrgB gene is located downstream from the nrgA gene. In E. coli, a gene (amtA) involved in ammonium transport has been cloned and sequenced (Fabiny et al, 1991;Jayakumar et al, 1989). The AmtA protein has been predicted to be a cytoplasmic component of an ammonium-transport system (Fabiny et al, 1991) and is not homologous to the ORF cloned in this study.…”

Section: Glnk Can Activate the Adenylylation Of Gs In Vitromentioning

confidence: 92%

An alternative P_II protein in the regulation of glutamine synthetase in Escherichia coli

Heeswijk

Hoving

Molenaar

et al. 1996

Molecular Microbiology

199

291

View full text Add to dashboard Cite

SummaryThe P II protein has been considered pivotal to the dual cascade regulating ammonia assimilation through glutamine synthetase activity. Here we show that P II , encoded by the glnB gene, is not always essential; for instance upon ammonia deprivation of a glnB deletion strain, glutamine synthetase can be deadenylylated as effectively as in the wild-type strain. We describe a new operon, glnK amtB, which encodes a homologue of P II and a putative ammonia transporter. We cloned and overexpressed glnK and found that the expressed protein had almost the same molecular weight as P II , reacted with polyclonal P II antibody, and was 67% identical in terms of amino acid sequence with Escherichia coli P II . Like P II , purified GlnK can activate the adenylylation of glutamine synthetase in vitro, and, in vivo, the GlnK protein is uridylylated in a glnD-dependent fashion. Unlike P II , however, the expression of glnK depends on the presence of UTase, nitrogen regulator I (NRI), and absence of ammonia. Because of a NRI and a r N (r 54 ) RNA polymerase-binding consensus sequence upstream from the glnK gene, this suggests that glnK is regulated through the NRI/ NRII two-component regulatory system. Indeed, in cells grown in the presence of ammonia, glutamine synthetase deadenylylation upon ammonia depletion depended on P II . Possible regulatory implications of this conditional redundancy of P II are discussed.

show abstract

Section: Glnk Can Activate the Adenylylation Of Gs In Vitromentioning

confidence: 92%

An alternative P_II protein in the regulation of glutamine synthetase in Escherichia coli

Heeswijk

Hoving

Molenaar

et al. 1996

Molecular Microbiology

199

291

View full text Add to dashboard Cite

show abstract

“…Studies with mutant strains, which have lost the ability to actively transport NH,+ (Amt-), support this argument. For example, Klebsiella pneumoniae (Amt-) can grow only when NH4+, as sole source of N, is > 2 mM (Kleiner 1985), and E. coli (Amt-) cannot grow on 100 PM NH4+, whereas the Amt+ strain can (Jayakumar et al 1989). Passive NH3 diffusion will be an important transport mechanism when its rate is greater than cellular N demand.…”

Section: Discussionmentioning

confidence: 99%

“…Activity of Amt and GS increased when V. harveyi grew on 5 1 mM NH,+. It is likely that transcription of the genes for Amt and GS is being derepressed simultaneously (Jayakumar et al 1986). Our V. harveyi results suggest that low and high affinity pathways of NH,+ uptake are operating together when extracellular NH,+ is within the range of N 0. l-l mM.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Isotope fractionation associated with ammonium uptake by a marine bacterium

Hoch

Fogel

Kirchman

1992

Limnology & Oceanography

216

179

View full text Add to dashboard Cite

Bacteria can account for a large fraction of total NH,' uptake in both pelagic and benthic marine environments. 15N natural abundance was examined to understand the effect of NH,' uptake by bacteria on nitrogen isotope biogeochemistry. Isotope fractionation (E) for NH,' uptake by the marine bacterium Vibrio harveyi changed from -4 to -277~ when cells were grown on 23-l 82 PM NH,+ and then from -27 to -14Ya when the NH;' concentration increased to 23.3 mM. Changes in fractionation correlated with a switch in the pathway of NH,' uptake from membrane diffusion of NH, and assimilation catalyzed by glutamate dehydrogcnase at millimolar NH,' to active ammonium transport (Amt) and assimilation catalyzed by glutamine synthetase (GS) at micromolar NH,+. This transition occurred between 0.1 and I mM NH,+. Within this concentration range, cellular N demand was no longer supported by Fickian diffusion of NH:, and Amt activity increased. The isotope fractionation of whole cells with the highest GS activity (E = -4%) and that measured for the GS-catalyzed reaction in vitro (E = -8%; pH = 7

show abstract

“…Energy-dependent uptake of ammonium under limiting nitrogen supply has been described for bacteria (1) and fungi (3,4). Genetic studies identified genes of ammonium transporters (Amts) and methylamine permeases (Meps) and permitted investigation of their activity and regulation (3,5). The most widely accepted view is that they are secondary transporters mediating the uptake of the ammonium cation (6)(7)(8).…”

mentioning

confidence: 99%

The mechanism of ammonia transport based on the crystal structure of AmtB of Escherichia coli

Zheng

Kostrewa

Bernèche

et al. 2004

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

308

476

View full text Add to dashboard Cite

Ammonium is one of the most important nitrogen sources for bacteria, fungi, and plants, but it is toxic to animals. The ammonium transport proteins (methylamine permeases͞ammonium transporters͞rhesus) are present in all domains of life; however, functional studies with members of this family have yielded controversial results with respect to the chemical identity (NH 4 ؉ or NH 3) of the transported species. We have solved the structure of wild-type AmtB from Escherichia coli in two crystal forms at 1.8-and 2.1-Å resolution, respectively. Substrate transport occurs through a narrow mainly hydrophobic pore located at the center of each monomer of the trimeric AmtB. At the periplasmic entry, a binding site for NH 4 ؉ is observed. Two phenylalanine side chains (F107 and F215) block access into the pore from the periplasmic side. Further into the pore, the side chains of two highly conserved histidine residues (H168 and H318) bridged by a H-bond lie adjacent, with their edges pointing into the cavity. These histidine residues may facilitate the deprotonation of an ammonium ion entering the pore. Adiabatic free energy calculations support the hypothesis that an electrostatic barrier between H168 and H318 hinders the permeation of cations but not that of the uncharged NH 3. The structural data and energetic considerations strongly indicate that the methylamine permeases͞ammonium transporters͞rhesus proteins are ammonia gas channels. Interestingly, at the cytoplasmic exit of the pore, two different conformational states are observed that might be related to the inactivation mechanism by its regulatory partner.conformational change ͉ x-ray structure

show abstract

Isolation of an ammonium or methylammonium ion transport mutant of Escherichia coli and complementation by the cloned gene

Cited by 28 publications

References 27 publications

An alternative P_II protein in the regulation of glutamine synthetase in Escherichia coli

An alternative P_II protein in the regulation of glutamine synthetase in Escherichia coli

Isotope fractionation associated with ammonium uptake by a marine bacterium

The mechanism of ammonia transport based on the crystal structure of AmtB of Escherichia coli

Contact Info

Product

Resources

About

Isolation of an ammonium or methylammonium ion transport mutant of Escherichia coli and complementation by the cloned gene

Cited by 28 publications

References 27 publications

An alternative PII protein in the regulation of glutamine synthetase in Escherichia coli

An alternative PII protein in the regulation of glutamine synthetase in Escherichia coli

Isotope fractionation associated with ammonium uptake by a marine bacterium

The mechanism of ammonia transport based on the crystal structure of AmtB of Escherichia coli

Contact Info

Product

Resources

About

An alternative P_II protein in the regulation of glutamine synthetase in Escherichia coli

An alternative P_II protein in the regulation of glutamine synthetase in Escherichia coli