Complex formation between AmtB and GlnK: an ancestral role in prokaryotic nitrogen control

2005 ◽  
Vol 33 (1) ◽  
pp. 170-172 ◽  
Author(s):  
A. Javelle ◽  
M. Merrick
Keyword(s):  
Escherichia Coli ◽  
Signal Transduction ◽  
Sensory System ◽  
Transport Proteins ◽  
Ammonium Transport ◽  
Nitrogen Control ◽  
Regulatory Processes ◽  
Signal Transduction Protein ◽  
Pii Proteins ◽  
Invariant Coupling

Ammonium transport proteins belonging to the Amt family are ubiquitous in prokaryotes. In Escherichia coli, the AmtB protein and the associated PII signal transduction protein (GlnK) have recently been recognized as an ammonium sensory system that effectively couples the intracellular nitrogen regulation (Ntr) system to external changes in ammonium availability. Given the almost invariant coupling of AmtB and GlnK in bacteria and archaea it seems probable that these two proteins may constitute an ancestral nitrogen-responsive system that has been coupled with a variety of unrelated nitrogen regulatory processes, which are now found in prokaryotes. The multiplicity of PII proteins could therefore be considered to have evolved from an ancestral GlnK-like protein and to have subsequently been adapted to control many other aspects of nitrogen metabolism.

scholarly journals Role of Escherichia coli Nitrogen Regulatory Genes in the Nitrogen Response of the Azotobacter vinelandiiNifL-NifA Complex

2001 ◽  
Vol 183 (10) ◽  
pp. 3076-3082 ◽  
Author(s):  
Francisca Reyes-Ramirez ◽  
Richard Little ◽  
Ray Dixon
Keyword(s):  
Escherichia Coli ◽  
Signal Transduction ◽  
Nitrogen Control ◽  
Fixed Nitrogen ◽  
Nitrogen Response ◽  
E Coli ◽  
Nitrogen Excess

ABSTRACT The redox-sensing flavoprotein NifL inhibits the activity of the nitrogen fixation (nif)-specific transcriptional activator NifA in Azotobacter vinelandii in response to molecular oxygen and fixed nitrogen. Although the mechanism whereby the A. vinelandii NifL-NifA system responds to fixed nitrogen in vivo is unknown, the glnK gene, which encodes a PII-like signal transduction protein, has been implicated in nitrogen control. However, the precise function of A. vinelandii glnK in this response is difficult to establish because of the essential nature of this gene. We have shown previously that A. vinelandii NifL is able to respond to fixed nitrogen to control NifA activity when expressed inEscherichia coli. In this study, we investigated the role of the E. coli PII-like signal transduction proteins in nitrogen control of the A. vinelandii NifL-NifA regulatory system in vivo. In contrast to recent findings with Klebsiella pneumoniae NifL, our results indicate that neither the E. coli PII nor GlnK protein is required to relieve inhibition byA. vinelandii NifL under nitrogen-limiting conditions. Moreover, disruption of both the E. coli glnB andntrC genes resulted in a complete loss of nitrogen regulation of NifA activity by NifL. We observe that glnB ntrC and glnB glnK ntrC mutant strains accumulate high levels of intracellular 2-oxoglutarate under conditions of nitrogen excess. These findings are in accord with our recent in vitro observations (R. Little, F. Reyes-Ramirez, Y. Zhang, W. Van Heeswijk, and R. Dixon, EMBO J. 19:6041–6050, 2000) and suggest a model in which nitrogen control of the A. vinelandii NifL-NifA system is achieved through the response to the level of 2-oxoglutarate and an interaction with PII-like proteins under conditions of nitrogen excess.

X-ray structure of the signal transduction protein from Escherichia coli at 1.9 Å

1996 ◽  
Vol 52 (1) ◽  
pp. 93-104 ◽  
Author(s):  
P. D. Carr ◽  
E. Cheah ◽  
P. M. Suffolk ◽  
S. G. Vasudevan ◽  
N. E. Dixon ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Signal Transduction ◽  
X Ray ◽  
Signal Transduction Protein

scholarly journals PII T-Loop Mutations Affecting Signal Transduction to NtrB Also Abolish Yeast Two-Hybrid Interactions

2002 ◽  
Vol 184 (13) ◽  
pp. 3746-3748 ◽  
Author(s):  
Isabel Martínez-Argudo ◽  
Asunción Contreras
Keyword(s):  
Escherichia Coli ◽  
Signal Transduction ◽  
Hybrid System ◽  
Yeast Two Hybrid ◽  
Regulatory Interactions ◽  
Pii Protein ◽  
Yeast Two Hybrid System ◽  
Two Component ◽  
Pii Proteins ◽  
Two Hybrid

ABSTRACT Mutations A49P and Δ47-53 at the T loop of the Escherichia coli GlnB (PII) protein impair regulatory interactions with the two-component sensor regulator NtrB (P. Jiang, P. Zucker, M. R. Atkinson, E. S. Kamberov, W. Tirasophon, P. Chandran, B. R. Schepke, and A. J. Ninfa, J. Bacteriol. 179: 4342-4353, 1997). We show here that these mutations also impair interactions between PII and NtrB in the yeast two-hybrid system, indicating that defects in NtrB regulation closely reflect binding impairment. The reported results underline the strength of two-hybrid assays for analysis of interactions involving the T loop of PII proteins.

scholarly journals Gas Channels for NH3: Proteins from Hyperthermophiles Complement an Escherichia coli Mutant

2002 ◽  
Vol 184 (12) ◽  
pp. 3396-3400 ◽  
Author(s):  
Eric Soupene ◽  
Tony Chu ◽  
Rebecca W. Corbin ◽  
Donald F. Hunt ◽  
Sydney Kustu
Keyword(s):  
Escherichia Coli ◽  
Affinity Chromatography ◽  
Membrane Transport ◽  
Transport Proteins ◽  
Ammonium Transport ◽  
Aquifex Aeolicus ◽  
Membrane Transport Proteins ◽  
Nickel Chelate ◽  
Mesophilic Bacterium ◽  
Low Expression

ABSTRACT Ammonium transport (Amt) proteins appear to be bidirectional channels for NH3. The amt genes of the hyperthermophiles Aquifex aeolicus and Methanococcus jannaschii complement enteric amtB mutants for growth at 25 nM NH3 at 37°C. To our knowledge, Amt proteins are the first hyperthermophilic membrane transport proteins shown to be active in a mesophilic bacterium. Despite low expression levels, His-tagged Aquifex Amt could be purified by heating and nickel chelate affinity chromatography. It could be studied genetically in Escherichia coli.

scholarly journals The Signal Transduction Protein GlnK Is Required for NifL-Dependent Nitrogen Control of nif Gene Expression in Klebsiella pneumoniae

1999 ◽  
Vol 181 (4) ◽  
pp. 1156-1162 ◽  
Author(s):  
Rachael Jack ◽  
Miklos De Zamaroczy ◽  
Mike Merrick
Keyword(s):  
Gene Expression ◽  
Signal Transduction ◽  
Klebsiella Pneumoniae ◽  
Amino Acid Sequences ◽  
Gene Products ◽  
Nitrogen Control ◽  
Fixed Nitrogen ◽  
Signal Transduction Protein ◽  
Unknown Factor ◽  
Signal Transduction Proteins

ABSTRACT In Klebsiella pneumoniae, transcription of the nitrogen fixation (nif) genes is regulated in response to molecular oxygen or availability of fixed nitrogen by the coordinated activities of the nifA and nifL gene products. NifA is anif-specific transcriptional activator, the activity of which is inhibited by interaction with NifL. Nitrogen control of NifL occurs at two levels: transcription of the nifLA operon is regulated by the global ntr system, and the inhibitory activity of NifL is controlled in response to fixed nitrogen by an unknown factor. K. pneumoniae synthesizes two PII-like signal transduction proteins, GlnB, which we have previously shown not to be involved in the response of NifL to fixed nitrogen, and the recently identified protein GlnK. We have now cloned the K. pneumoniae glnK gene, studied its expression, and shown that a null mutation in glnK prevents NifL from responding to the absence of fixed nitrogen, i.e., from relieving the inhibition of NifA activity. Hence, GlnK appears to be involved, directly or indirectly, in NifL-dependent regulation of nifgene expression in K. pneumoniae. Comparison of the GlnB and GlnK amino acid sequences from six species of proteobacteria identifies five residues (residues 3, 5, 52, 54, and 64) which serve to distinguish the GlnB and GlnK proteins.

scholarly journals Transcriptome and metabolome analyses of cold and darkness-induced pellicle cysts of Scrippsiella trochoidea

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Xin Guo ◽  
Zhaohui Wang ◽  
Lei Liu ◽  
Yang Li
Keyword(s):  
Signal Transduction ◽  
Sexual Reproduction ◽  
Harmful Algal Bloom ◽  
Transcriptional Response ◽  
Tca Cycle ◽  
Adaptive Strategy ◽  
Cyst Formation ◽  
Metabolite Profile ◽  
Scrippsiella Trochoidea ◽  
Regulatory Processes

Abstract Background Dinoflagellates are a group of unicellular organisms that are a major component of aquatic eukaryotes and important contributors to marine primary production. Nevertheless, many dinoflagellates are considered harmful algal bloom (HAB) species due to their detrimental environmental and human health impacts. Cyst formation is widely perceived as an adaptive strategy of cyst-forming dinoflagellates in response to adverse environmental conditions. Dinoflagellate cysts play critical roles in bloom dynamics. However, our insight into the underlying molecular basis of encystment is still limited. To investigate the molecular processes regulating encystment in dinoflagellates, transcriptome and metabolome investigations were performed on cold and darkness-induced pellicle cysts of Scrippsiella trochoidea. Results No significant transcriptional response was observed at 2 h; however, massive transcriptome and metabolome reprogramming occurred at 5 h and in pellicle cysts. The gene-to-metabolite network demonstrated that the initial transformation from vegetative cells into pellicle cysts was highly energy demanding through the activation of catabolism, including glycolysis, β-oxidation, TCA cycle and oxidative phosphorylation, to cope with cold-darkness-induced stress. However, after transformation into pellicle cysts, the metabolism was greatly reduced, and various sugars, polyunsaturated fatty acids and amino acids accumulated to prolong survival. The identification of 56 differentially expressed genes (DEGs) related to signal transduction indicated that S. trochoidea received a cold-darkness signal that activated multiple signal transduction pathways, leading to encystment. The elevated expression of genes encoding enzymes involved in ROS stress suggested that pellicle cysts respond to increased oxidative stress. Several cell cycle-related genes were repressed. Intriguingly, 11 DEGs associated with sexual reproduction suggested that pellicle cysts (or some portion thereof) may be a product of sexual reproduction. Conclusions This study provides the first transcriptome and metabolome analyses conducted during the encystment of S. trochoidea, an event that requires complex regulatory mechanisms and impacts on population dynamics. The results reveal comprehensive molecular regulatory processes underlying life cycle regulation in dinoflagellates involving signal transduction, gene expression and metabolite profile, which will improve our ability to understand and monitor dinoflagellate blooms.

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