1. Cross-talk and regulatory interactions between the essential response regulator RpaB and cyanobacterial circadian clock output.

    PNAS 112(7):2198 (2015) PMID 25653337 PMCID PMC4343135

    The response regulator RpaB (regulator of phycobilisome associated B), part of an essential two-component system conserved in cyanobacteria that responds to multiple environmental signals, has recently been implicated in the control of cell dimensions and of circadian rhythms of gene expression ...
  2. PipX, the coactivator of NtcA, is a global regulator in cyanobacteria.

    PNAS 111(23):E2423 (2014) PMID 24912181 PMCID PMC4060718

    To modulate the expression of genes involved in nitrogen assimilation, the cyanobacterial PII-interacting protein X (PipX) interacts with the global transcriptional regulator NtcA and the signal transduction protein PII, a protein found in all three domains of life as an integrator of signals of...
  3. Negative control of cell size in the cyanobacterium Synechococcus elongatus PCC 7942 by the essential response regulator RpaB.

    FEBS Letters 587(5):504 (2013) PMID 23340342

    The essential NblS-RpaB pathway for photosynthesis regulation and acclimatization to a variety of environmental conditions is the most conserved two-component system in cyanobacteria. To get insights into the RpaB implication in cell homeostasis we investigated the phenotypic impact of altering ...
  4. In vivo features of signal transduction by the essential response regulator RpaB from Synechococcus elongatus PCC 7942.

    Microbiology 158(Pt 5):1229 (2012) PMID 22322959

    The NblS-RpaB signalling pathway, the most conserved two-component system in cyanobacteria, regulates photosynthesis and acclimatization to a variety of environmental conditions and is involved in negative regulation of high-light-induced genes. However, relevant regulatory details of the NblS-R...
  5. Insights into the mechanism of activation of the phosphorylation-independent response regulator NblR. Role of residues Cys69 and Cys96.

    Biochimica et Biophysica Acta 1819(5):382 (2012) PMID 22306661

    Cyanobacteria respond to environmental stress conditions by adjusting their photosynthesis machinery. In Synechococcus sp. PCC 7942, phycobilisome degradation and other acclimation responses after nutrient or high light stress require activation by the phosphorylation-independent response regula...
  6. Mutational analysis of the cyanobacterial nitrogen regulator PipX.

    PLoS ONE 7(4):e35845 (2012) PMID 22558239 PMCID PMC3340408

    PipX provides a functional link between the cyanobacterial global transcriptional regulator NtcA and the signal transduction protein P(II), a protein found in all three domains of life as integrators of signals of the nitrogen and carbon balance. PipX, which is toxic in the absence of P(II), can...
  7. The nitrogen interaction network in Synechococcus WH5701, a cyanobacterium with two PipX and two P(II)-like proteins.

    Microbiology 157(Pt 4):1220 (2011) PMID 21183574

    Nitrogen regulation involves the formation of different types of protein complexes between signal transducers and their transcriptional or metabolic targets. In oxygenic phototrophs, the signal integrator P(II) activates the enzyme N-acetyl-l-glutamate kinase (NAGK) by complex formation. P(II) a...
  8. Environmental control of phosphorylation pathways in a branched two-component system.

    Molecular Microbiology 78(2):475 (2010) PMID 20979345

    NblS, the most conserved histidine kinase in cyanobacteria, regulates photosynthesis and acclimatization to a variety of environmental conditions. We used in silico, in vivo and in vitro approaches to identify RpaB and SrrA as the cognate response regulators of NblS and to characterize relevant ...
  9. Structural basis for the regulation of NtcA-dependent transcription by proteins PipX and PII.

    PNAS 107(35):15397 (2010) PMID 20716687 PMCID PMC2932567

    PII, an ancient and widespread signaling protein, transduces nitrogen/carbon/energy abundance signals through interactions with target proteins. We clarify structurally how PII regulates gene expression mediated by the transcription factor NtcA, the global nitrogen regulator of cyanobacteria, sh...
  10. Effects of spontaneous mutations in PipX functions and regulatory complexes on the cyanobacterium Synechococcus elongatus strain PCC 7942.

    Microbiology 156(Pt 5):1517 (2010) PMID 20110304

    In Synechococcus elongatus sp. PCC 7942, PipX forms complexes with P(II), a protein found in all three domains of life as an integrator of signals of the nitrogen and carbon balance, and with the cyanobacterial nitrogen regulator NtcA. We recently showed that previous inactivation of pipX facili...
  11. The regulatory factor SipA is a highly stable beta-II class protein with a SH3 fold.

    FEBS Letters 584(5):989 (2010) PMID 20102713

    The small regulator SipA, interacts with the ATP-binding domain of non-bleaching sensor histidine kinase (NblS), the most conserved histidine kinase in cyanobacteria. NblS regulates photosynthesis and acclimation to a variety of environmental conditions. We show here that SipA is a highly stable...
  12. Mutations at pipX suppress lethality of PII-deficient mutants of Synechococcus elongatus PCC 7942.

    Journal of Bacteriology 191(15):4863 (2009) PMID 19482921 PMCID PMC2715732

    The P(II) proteins are found in all three domains of life as key integrators of signals reflecting the balance of nitrogen and carbon. Genetic inactivation of P(II) proteins is typically associated with severe growth defects or death. However, the molecular basis of these defects depends on the ...
  13. Phosphorylation-independent activation of the atypical response regulator NblR.

    Microbiology 154(Pt 10):3002 (2008) PMID 18832306

    Cyanobacteria respond to environmental stress conditions by adjusting their photosynthesis machinery. In Synechococcus sp. PCC 7942, phycobilisome degradation and other acclimation responses after nutrient or high-light stress require activation by the orphan response regulator NblR, a member of...
  14. The regulatory factor SipA provides a link between NblS and NblR signal transduction pathways in the cyanobacterium Synechococcus sp. PCC 7942.

    Molecular Microbiology 66(6):1607 (2007) PMID 18004983

    Cyanobacteria respond to environmental stress conditions by adjusting its photosynthesis machinery. When subjected to nutrient and high light stress, Synechococcus sp. PCC 7942 and other non-diazotrophic cyanobacteria degrade their phycobilisome, the light-harvesting complexes for photosynthesis...
  15. The crystal structure of the complex of PII and acetylglutamate kinase reveals how PII controls the storage of nitrogen as arginine.

    PNAS 104(45):17644 (2007) PMID 17959776 PMCID PMC2077032

    Photosynthetic organisms can store nitrogen by synthesizing arginine, and, therefore, feedback inhibition of arginine synthesis must be relieved in these organisms when nitrogen is abundant. This relief is accomplished by the binding of the PII signal transduction protein to acetylglutamate kina...
  16. Role of the Synechococcus PCC 7942 nitrogen regulator protein PipX in NtcA-controlled processes.

    Microbiology 153(Pt 3):711 (2007) PMID 17322191

    The Synechococcus sp. PCC 7942 nitrogen regulator PipX interacts in a 2-oxoglutarate-dependent manner with the global nitrogen transcription factor NtcA and the signal transduction protein P(II). In vivo, PipX is involved in the NtcA-dependent induction of glnB and glnN genes. To further investi...
  17. Interaction network in cyanobacterial nitrogen regulation: PipX, a protein that interacts in a 2-oxoglutarate dependent manner with PII and NtcA.

    Molecular Microbiology 61(2):457 (2006) PMID 16796668

    Cyanobacteria perceive nitrogen status by sensing intracellular 2-oxoglutarate levels. The global nitrogen transcription factor NtcA and the signal transduction protein PII are both involved in 2-oxoglutarate sensing. PII proteins, probably the most conserved signal transduction proteins in natu...
  18. SipA, a novel type of protein from Synechococcus sp. PCC 7942, binds to the kinase domain of NblS.

    FEMS Microbiology Letters 254(1):41 (2006) PMID 16451177

    Cyanobacteria respond to nutrient stress conditions by degrading their light-harvesting complexes for photosynthesis, a process regulated in Synechococcus sp. PCC 7942 by the sensor histidine kinase non-bleaching sensor (NblS). In yeast two-hybrid screenings for proteins interacting with NblS we...
  19. Interactions between the nitrogen signal transduction protein PII and N-acetyl glutamate kinase in organisms that perform oxygenic photosynthesis.

    Journal of Bacteriology 186(11):3346 (2004) PMID 15150219 PMCID PMC415743

    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 ...
  20. Expression of the glutamyl-tRNA synthetase gene from the cyanobacterium Synechococcus sp PCC 7942 depends on nitrogen availability and the global regulator NtcA.

    Molecular Microbiology 46(4):1157 (2002) PMID 12421319

    We report here transcriptional analyses of a cyanobacterial gene encoding an aminoacyl-tRNA synthetase (aaRS), the gltX gene from Synechoccocus sp. PCC 7942, coding for the glutamyl-tRNA synthetase. We show that the transcript levels of gltX in Synechococcus depend on nitrogen availability and d...