scholarly journals The First Proteomic Study of Nostoc sp. PCC 7120 Exposed to Cyanotoxin BMAA under Nitrogen Starvation

Toxins ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 310 ◽  
Author(s):  
Olga A. Koksharova ◽  
Ivan O. Butenko ◽  
Olga V. Pobeguts ◽  
Nina A. Safronova ◽  
Vadim M. Govorun
Keyword(s):  
Amino Acid ◽  
Nitrogen Metabolism ◽  
Nitrogen Starvation ◽  
Practical Interest ◽  
Trna Synthetase ◽  
Water Soluble ◽  
Protein Amino Acid ◽  
Heterocyst Differentiation ◽  
Proteomic Study ◽  
Pcc 7120

The oldest prokaryotic photoautotrophic organisms, cyanobacteria, produce many different metabolites. Among them is the water-soluble neurotoxic non-protein amino acid beta-N-methylamino-L-alanine (BMAA), whose biological functions in cyanobacterial metabolism are of fundamental scientific and practical interest. An early BMAA inhibitory effect on nitrogen fixation and heterocyst differentiation was shown in strains of diazotrophic cyanobacteria Nostoc sp. PCC 7120, Nostoc punctiforme PCC 73102 (ATCC 29133), and Nostoc sp. strain 8963 under conditions of nitrogen starvation. Herein, we present a comprehensive proteomic study of Nostoc (also called Anabaena) sp. PCC 7120 in the heterocyst formation stage affecting by BMAA treatment under nitrogen starvation conditions. BMAA disturbs proteins involved in nitrogen and carbon metabolic pathways, which are tightly co-regulated in cyanobacteria cells. The presented evidence shows that exogenous BMAA affects a key nitrogen regulatory protein, PII (GlnB), and some of its protein partners, as well as glutamyl-tRNA synthetase gltX and other proteins that are involved in protein synthesis, heterocyst differentiation, and nitrogen metabolism. By taking into account the important regulatory role of PII, it becomes clear that BMAA has a severe negative impact on the carbon and nitrogen metabolism of starving Nostoc sp. PCC 7120 cells. BMAA disturbs carbon fixation and the carbon dioxide concentrating mechanism, photosynthesis, and amino acid metabolism. Stress response proteins and DNA repair enzymes are upregulated in the presence of BMAA, clearly indicating severe intracellular stress. This is the first proteomic study of the effects of BMAA on diazotrophic starving cyanobacteria cells, allowing a deeper insight into the regulation of the intracellular metabolism of cyanobacteria by this non-protein amino acid.

scholarly journals c-di-GMP Homeostasis Is Critical for Heterocyst Development in Anabaena sp. PCC 7120

2021 ◽  
Vol 12 ◽  
Author(s):  
Min Huang ◽  
Ju-Yuan Zhang ◽  
Xiaoli Zeng ◽  
Cheng-Cai Zhang
Keyword(s):  
Nitrogen Starvation ◽  
Filamentous Cyanobacterium ◽  
Nitrogen Deprivation ◽  
Heterocyst Differentiation ◽  
Combined Nitrogen ◽  
Heterocyst Frequency ◽  
Genes Encoding ◽  
Anabaena Sp ◽  
Opposing Effects ◽  
Pcc 7120

c-di-GMP is a ubiquitous bacterial signal regulating various physiological process. Anabaena PCC 7120 (Anabaena) is a filamentous cyanobacterium able to form regularly-spaced heterocysts for nitrogen fixation, in response to combined-nitrogen deprivation in 24h. Anabaena possesses 16 genes encoding proteins for c-di-GMP metabolism, and their functions are poorly characterized, except all2874 (cdgS) whose deletion causes a decrease in heterocyst frequency 48h after nitrogen starvation. We demonstrated here that c-di-GMP levels increased significantly in Anabaena after combined-nitrogen starvation. By inactivating each of the 16 genes, we found that the deletion of all1175 (cdgSH) led to an increase of heterocyst frequency 24h after nitrogen stepdown. A double mutant ΔcdgSHΔcdgS had an additive effect over the single mutants in regulating heterocyst frequency, indicating that the two genes acted at different time points for heterocyst spacing. Biochemical and genetic data further showed that the functions of CdgSH and CdgS in the setup or maintenance of heterocyst frequency depended on their opposing effects on the intracellular levels of c-di-GMP. Finally, we demonstrated that heterocyst differentiation was completely inhibited when c-di-GMP levels became too high or too low. Together, these results indicate that the homeostasis of c-di-GMP level is important for heterocyst differentiation in Anabaena.

Nitrogen metabolism and growth performance of gilts fed standard corn-soybean meal diets or low-crude protein, amino acid-supplemented diets1

2002 ◽  
Vol 80 (11) ◽  
pp. 2911-2919 ◽  
Author(s):  
J. L. Figueroa ◽  
A. J. Lewis ◽  
P. S. Miller ◽  
R. L. Fischer ◽  
R. S. Gómez ◽  
...  
Keyword(s):  
Amino Acid ◽  
Growth Performance ◽  
Nitrogen Metabolism ◽  
Soybean Meal ◽  
Crude Protein ◽  
Protein Amino Acid

scholarly journals Transferability of N-terminal mutations of pyrrolysyl-tRNA synthetase in one species to that in another species on unnatural amino acid incorporation efficiency

Amino Acids ◽  
2020 ◽  
Author(s):  
Thomas L. Williams ◽  
Debra J. Iskandar ◽  
Alexander R. Nödling ◽  
Yurong Tan ◽  
Louis Y. P. Luk ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Genetic Code ◽  
Unnatural Amino Acids ◽  
Trna Synthetase ◽  
Unnatural Amino Acid ◽  
Amino Acid Incorporation ◽  
Acid Incorporation ◽  
Genetic Code Expansion ◽  
Incorporation Efficiency

AbstractGenetic code expansion is a powerful technique for site-specific incorporation of an unnatural amino acid into a protein of interest. This technique relies on an orthogonal aminoacyl-tRNA synthetase/tRNA pair and has enabled incorporation of over 100 different unnatural amino acids into ribosomally synthesized proteins in cells. Pyrrolysyl-tRNA synthetase (PylRS) and its cognate tRNA from Methanosarcina species are arguably the most widely used orthogonal pair. Here, we investigated whether beneficial effect in unnatural amino acid incorporation caused by N-terminal mutations in PylRS of one species is transferable to PylRS of another species. It was shown that conserved mutations on the N-terminal domain of MmPylRS improved the unnatural amino acid incorporation efficiency up to five folds. As MbPylRS shares high sequence identity to MmPylRS, and the two homologs are often used interchangeably, we examined incorporation of five unnatural amino acids by four MbPylRS variants at two temperatures. Our results indicate that the beneficial N-terminal mutations in MmPylRS did not improve unnatural amino acid incorporation efficiency by MbPylRS. Knowledge from this work contributes to our understanding of PylRS homologs which are needed to improve the technique of genetic code expansion in the future.

Sign in / Sign up

Export Citation Format

Share Document