scholarly journals Interactions between the Nitrogen Signal Transduction Protein PII and N-Acetyl Glutamate Kinase in Organisms That Perform Oxygenic Photosynthesis

2004 ◽  
Vol 186 (11) ◽  
pp. 3346-3354 ◽  
Author(s):  
Sergio Burillo ◽  
Ignacio Luque ◽  
Inmaculada Fuentes ◽  
Asunción Contreras
Keyword(s):  
Signal Transduction ◽  
Oxygenic Photosynthesis ◽  
Yeast Two Hybrid ◽  
Hybrid Approaches ◽  
Signal Transduction Protein ◽  
Photosynthetic Eukaryotes ◽  
Key Enzyme ◽  
Signal Transduction Proteins ◽  
Pcc 7942 ◽  
Two Hybrid

ABSTRACT PII, one of the most conserved signal transduction proteins, is believed to be a key player in the coordination of nitrogen assimilation and carbon metabolism in bacteria, archaea, and plants. However, the identity of PII receptors remains elusive, particularly in photosynthetic organisms. Here we used yeast two-hybrid approaches to identify new PII receptors and to explore the extent of conservation of PII signaling mechanisms between eubacteria and photosynthetic eukaryotes. Screening of Synechococcus sp. strain PCC 7942 libraries with PII as bait resulted in identification of N-acetyl glutamate kinase (NAGK), a key enzyme in the biosynthesis of arginine. The integrity of Ser49, a residue conserved in PII proteins from organisms that perform oxygenic photosynthesis, appears to be essential for NAGK binding. The effect of glnB mutations on NAGK activity is consistent with positive regulation of NAGK by PII. Phylogenetic and yeast two-hybrid analyses strongly suggest that there was conservation of the NAGK-PII regulatory interaction in the evolution of cyanobacteria and chloroplasts, providing insight into the function of eukaryotic PII-like proteins.

scholarly journals Signal-transduction protein PII from Synechococcus elongatus PCC 7942 senses low adenylate energy charge in vitro

2011 ◽  
Vol 440 (1) ◽  
pp. 147-156 ◽  
Author(s):  
Oleksandra Fokina ◽  
Christina Herrmann ◽  
Karl Forchhammer
Keyword(s):  
Signal Transduction ◽  
Energy Charge ◽  
Inhibitory Effect ◽  
Synechococcus Elongatus ◽  
Adenylate Energy Charge ◽  
Signal Transduction Protein ◽  
Signal Transduction Proteins ◽  
Synechococcus Elongatus Pcc 7942 ◽  
And Control

PII proteins belong to a family of highly conserved signal-transduction proteins that occurs widely in bacteria, archaea and plants. They respond to the central metabolites ATP, ADP and 2-OG (2-oxoglutarate), and control enzymes, transcription factors and transport proteins involved in nitrogen metabolism. In the present study, we examined the effect of ADP on in vitro PII-signalling properties for the cyanobacterium Synechococcus elongatus, a model for oxygenic phototrophic organisms. Different ADP/ATP ratios strongly affected the properties of PII signalling. Increasing ADP antagonized the binding of 2-OG and directly affected the interactions of PII with its target proteins. The resulting PII-signalling properties indicate that, in mixtures of ADP and ATP, PII trimers are occupied by mixtures of adenylate nucleotides. Binding and kinetic activation of NAGK (N-acetyl-L-glutamate kinase), the controlling enzyme of arginine biosynthesis, by PII was weakened by ADP, but relief from arginine inhibition remained unaffected. On the other hand, ADP enhanced the binding of PII to PipX, a co-activator of the transcription factor NtcA and, furthermore, antagonized the inhibitory effect of 2-OG on PII–PipX interaction. These results indicate that S. elongatus PII directly senses the adenylate energy charge, resulting in target-dependent differential modification of the PII-signalling properties.

scholarly journals PII-Regulated Arginine Synthesis Controls Accumulation of Cyanophycin in Synechocystis sp. Strain PCC 6803

2006 ◽  
Vol 188 (7) ◽  
pp. 2730-2734 ◽  
Author(s):  
Mani Maheswaran ◽  
Karl Ziegler ◽  
Wolfgang Lockau ◽  
Martin Hagemann ◽  
Karl Forchhammer
Keyword(s):  
Signal Transduction ◽  
Aspartic Acid ◽  
Heterotrophic Bacteria ◽  
Nitrogen Storage ◽  
Arginine Biosynthesis ◽  
Signal Transduction Protein ◽  
Key Enzyme ◽  
Nitrogen Excess ◽  
Synechocystis Sp ◽  
Pcc 6803

ABSTRACT Cyanophycin (multi-l-arginyl-poly-l-aspartic acid) is a nitrogen storage polymer found in most cyanobacteria and some heterotrophic bacteria. The cyanobacterium Synechocystis sp. strain PCC 6803 accumulates cyanophycin following a transition from nitrogen-limited to nitrogen-excess conditions. Here we show that the accumulation of cyanophycin depends on the activation of the key enzyme of arginine biosynthesis, N-acetyl-l-glutamate kinase, by signal transduction protein PII.

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 Fishing out proteins that bind to titin

2001 ◽  
Vol 154 (1) ◽  
pp. 21-24 ◽  
Author(s):  
Joseph W. Sanger ◽  
Jean M. Sanger
Keyword(s):  
Signal Transduction ◽  
Molecular Weight ◽  
Embryonic Development ◽  
Striated Muscle ◽  
Muscle Cells ◽  
Small Region ◽  
Yeast Two Hybrid ◽  
Two Hybrid

Another giant protein has been detected in cross-striated muscle cells. Given the name obscurin, it was discovered in a yeast two-hybrid screen in which the bait was a small region of titin that is localized near the Z-band. Obscurin is about 720 kD, similar in molecular weight to nebulin, but present at about one tenth the level (Young et al., 2001). Like titin, obscurin contains multiple immunoglobulin-like domains linked in tandem, but in contrast to titin it contains just two fibronectin-like domains. It also contains sequences that suggest obscurin may have roles in signal transduction. During embryonic development, its localization changes from the Z-band to the M-band. With these intriguing properties, obscurin may not remain obscure for long.

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.

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