Expression of GlnB and Role of the PII Protein in Nitrogen Assimilation in Synechococcus sp. PCC 7942

1998 ◽  
pp. 171-171
Author(s):  
H. M. Lee ◽  
E. Flores ◽  
A. Herrero ◽  
J. Houmard ◽  
N. Tandeau de Marsac
Keyword(s):  
Nitrogen Assimilation ◽  
Pii Protein ◽  
Synechococcus Sp ◽  
Pcc 7942

scholarly journals Dissection of the Mechanisms of Growth Inhibition Resulting from Loss of the PII Protein in the CyanobacteriumSynechococcus elongatusPCC 7942

2021 ◽  
Author(s):  
Takayuki Sakamoto ◽  
Nobuyuki Takatani ◽  
Kintake Sonoike ◽  
Haruhiko Jimbo ◽  
Yoshitaka Nishiyama ◽  
...  
Keyword(s):  
Nitrogen Assimilation ◽  
Growth Defect ◽  
Oxygen Species ◽  
Wild Type ◽  
Pii Protein ◽  
Regulator Protein ◽  
Synechococcus Elongatus Pcc 7942 ◽  
Pcc 7942 ◽  
Mutant Cells

AbstractIn cyanobacteria, the PII protein (the glnB gene product) regulates a number of proteins involved in nitrogen assimilation including PipX, the coactivator of the global nitrogen regulator protein NtcA. In Synechococcus elongatus PCC 7942, construction of a PII-less mutant retaining the wild-type pipX gene is difficult because of the toxicity of uncontrolled action of PipX and the other defect(s) resulting from the loss of PII  per se, but the nature of the PipX toxicity and the PipX-independent defect(s) remains unclear. Characterization of a PipX-less glnB mutant (PD4) in this study showed that the loss of PII increases the sensitivity of PSII to ammonium. Ammonium was shown to stimulate the formation of reactive oxygen species in the mutant cells. The ammonium-sensitive growth phenotype of PD4 was rescued by the addition of an antioxidant α-tocopherol, confirming that photo-oxidative damage was the major cause of the growth defect. A targeted PII mutant retaining wild-type pipX was successfully constructed from the wild-type S. elongatus strain (SPc) in the presence of α-tocopherol. The resulting mutant (PD1X) showed an unusual chlorophyll fluorescence profile, indicating extremely slow reduction and re-oxidation of QA, which was not observed in mutants defective in both glnB and pipX. These results showed that the aberrant action of uncontrolled PipX resulted in an impairment of the electron transport reactions in both the reducing and oxidizing sides of QA.

scholarly journals Gut bacteria are essential for normal cuticle development in herbivorous turtle ants

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Christophe Duplais ◽  
Vincent Sarou-Kanian ◽  
Dominique Massiot ◽  
Alia Hassan ◽  
Barbara Perrone ◽  
...  
Keyword(s):  
Evolutionary History ◽  
Nitrogen Assimilation ◽  
Isotope Ratio Mass Spectrometry ◽  
Gut Bacteria ◽  
Resonance Spectroscopy ◽  
Nitrogen Flow ◽  
Isotopic Enrichment ◽  
History Of ◽  
Cuticle Development

AbstractAcross the evolutionary history of insects, the shift from nitrogen-rich carnivore/omnivore diets to nitrogen-poor herbivorous diets was made possible through symbiosis with microbes. The herbivorous turtle ants Cephalotes possess a conserved gut microbiome which enriches the nutrient composition by recycling nitrogen-rich metabolic waste to increase the production of amino acids. This enrichment is assumed to benefit the host, but we do not know to what extent. To gain insights into nitrogen assimilation in the ant cuticle we use gut bacterial manipulation, 15N isotopic enrichment, isotope-ratio mass spectrometry, and 15N nuclear magnetic resonance spectroscopy to demonstrate that gut bacteria contribute to the formation of proteins, catecholamine cross-linkers, and chitin in the cuticle. This study identifies the cuticular components which are nitrogen-enriched by gut bacteria, highlighting the role of symbionts in insect evolution, and provides a framework for understanding the nitrogen flow from nutrients through bacteria into the insect cuticle.

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