Influence of monovalent metal ions on metal binding and catalytic activity of the 10–23 DNAzyme

2020 ◽  
Vol 402 (1) ◽  
pp. 99-111
Author(s):  
Hannah Rosenbach ◽  
Jan Borggräfe ◽  
Julian Victor ◽  
Christine Wuebben ◽  
Olav Schiemann ◽  
...  
Keyword(s):  
Metal Ions ◽  
Metal Binding ◽  
Divalent Cations ◽  
Reaction Rates ◽  
Divalent Metal ◽  
Divalent Metal Ions ◽  
Monovalent Metal ◽  
Biophysical Techniques ◽  
Target Rna

AbstractDeoxyribozymes (DNAzymes) are single-stranded DNA molecules that catalyze a broad range of chemical reactions. The 10–23 DNAzyme catalyzes the cleavage of RNA strands and can be designed to cleave essentially any target RNA, which makes it particularly interesting for therapeutic and biosensing applications. The activity of this DNAzyme in vitro is considerably higher than in cells, which was suggested to be a result of the low intracellular concentration of bioavailable divalent cations. While the interaction of the 10–23 DNAzyme with divalent metal ions was studied extensively, the influence of monovalent metal ions on its activity remains poorly understood. Here, we characterize the influence of monovalent and divalent cations on the 10–23 DNAzyme utilizing functional and biophysical techniques. Our results show that Na+ and K+ affect the binding of divalent metal ions to the DNAzyme:RNA complex and considerably modulate the reaction rates of RNA cleavage. We observe an opposite effect of high levels of Na+ and K+ concentrations on Mg2+- and Mn2+-induced reactions, revealing a different interplay of these metals in catalysis. Based on these findings, we propose a model for the interaction of metal ions with the DNAzyme:RNA complex.

scholarly journals Regulation of divalent metal ions to the aggregation and membrane damage of human islet amyloid polypeptide oligomers

RSC Advances ◽  
2021 ◽  
Vol 11 (21) ◽  
pp. 12815-12825
Author(s):  
Yajie Wang ◽  
Feihong Meng ◽  
Tong Lu ◽  
Chunyun Wang ◽  
Fei Li
Keyword(s):  
Metal Ions ◽  
Metal Binding ◽  
Membrane Damage ◽  
Islet Amyloid Polypeptide ◽  
Divalent Metal ◽  
Human Islet ◽  
Divalent Metal Ions ◽  
Islet Amyloid ◽  
Induced Membrane ◽  
Human Islet Amyloid Polypeptide

Their is a counteraction between a decrease in the disruptive ability of metal-associated oligomer species and an increase in the quantity of oligomers promoted by the metal binding in the activity of hIAPP induced membrane damage.

Effect of Calcium and Other Minerals on Ripening of Tomatoes

1979 ◽  
Vol 6 (2) ◽  
pp. 221 ◽  
Author(s):  
RBH Wills ◽  
SIH Tirmazi
Keyword(s):  
Metal Ions ◽  
Colour Change ◽  
Calcium Content ◽  
Divalent Metal ◽  
Divalent Metal Ions ◽  
Fresh Weight ◽  
Ethylene Evolution ◽  
Ripening Process ◽  
Monovalent Metal ◽  
Sodium And Potassium

Ripening of green tomatoes (Lycopersicon esculentum) cv. Daydream, as expressed by change of colour, increased ethylene evolution and respiration, was inhibited when the calcium content of the fruit was raised to greater than 40 mg/100 g fresh weight (1 mmol Ca/100 g). The inhibition of ripening was long-lasting as such fruit showed no signs of ripening even after 6 weeks storage at 20°C, and the application of 1000 �l/l ethylene for 3 weeks had no effect. Application of calcium also inhibited the ripening process in tomatoes that had commenced ripening. Further change in colour was halted and a reduction in respiration and ethylene evolution was observed when calcium was applied at any stage of ripening including fully ripe. Inhibition of ripening was not specific to calcium as other divalent metal ions-manganese, cobalt and magnesium-were as effective as calcium, while the monovalent metal ions sodium and potassium were less effective than calcium but did give some retardation of ripening. Silver was as effective as the divalent metals in inhibiting colour change but its effect on ethylene production was similar to that obtained with sodium and potassium.

scholarly journals A Single Serine Residue Determines Selectivity to Monovalent Metal Ions in Metalloregulators of the MerR Family

2015 ◽  
Vol 197 (9) ◽  
pp. 1606-1613 ◽  
Author(s):  
María M. Ibáñez ◽  
Susana K. Checa ◽  
Fernando C. Soncini
Keyword(s):  
Metal Ions ◽  
Metal Binding ◽  
Metal Ion ◽  
Target Genes ◽  
Divalent Metal ◽  
Serine Residue ◽  
Ion Sensors ◽  
Monovalent Metal ◽  
Divalent Metal Ion ◽  
Metal Ion Sensors

ABSTRACTMerR metalloregulators alleviate toxicity caused by an excess of metal ions, such as copper, zinc, mercury, lead, cadmium, silver, or gold, by triggering the expression of specific efflux or detoxification systems upon metal detection. The sensor protein binds the inducer metal ion by using two conserved cysteine residues at the C-terminal metal-binding loop (MBL). Divalent metal ion sensors, such as MerR and ZntR, require a third cysteine residue, located at the beginning of the dimerization (α5) helix, for metal coordination, while monovalent metal ion sensors, such as CueR and GolS, have a serine residue at this position. This serine residue was proposed to provide hydrophobic and steric restrictions to privilege the binding of monovalent metal ions. Here we show that the presence of alanine at this position does not modify the activation pattern of monovalent metal sensors. In contrast, GolS or CueR mutant sensors with a substitution of cysteine for the serine residue respond to monovalent metal ions or Hg(II) with high sensitivities. Furthermore, in a mutant deleted of the Zn(II) exporter ZntA, they also trigger the expression of their target genes in response to either Zn(II), Cd(II), Pb(II), or Co(II).IMPORTANCESpecificity in a stressor's recognition is essential for mounting an appropriate response. MerR metalloregulators trigger the expression of specific resistance systems upon detection of heavy metal ions. Two groups of these metalloregulators can be distinguished, recognizing either +1 or +2 metal ions, depending on the presence of a conserved serine in the former or a cysteine in the latter. Here we demonstrate that the serine residue in monovalent metal ion sensors excludes divalent metal ion detection, as its replacement by cysteine renders a pan-metal ion sensor. Our results indicate that the spectrum of signals detected by these sensors is determined not only by the metal-binding ligand availability but also by the metal-binding cavity flexibility.

scholarly journals MOTOR END PLATE REACTIVITY TO DIVALENT METAL IONS HISTOCHEMICAL STUDIES

1967 ◽  
Vol 15 (5) ◽  
pp. 276-284 ◽  
Author(s):  
TOSHIO NAKAMURA ◽  
TATSUJI NAMBA ◽  
DAVID GROB
Keyword(s):  
Metal Ions ◽  
Metal Binding ◽  
Calcium Release ◽  
Cholinesterase Activity ◽  
Divalent Metal ◽  
Divalent Metal Ions ◽  
Alizarin Red ◽  
End Plate ◽  
Motor End Plate

Motor end plates in the tibialis anterior muscle of the rat were demonstrated by metal sulfide deposits following injection of aqueous solutions of lead, stannous, cadmium, zinc or cupric ions into the muscle in vivo or in vitro. The appearance of the end plates was similar to the structure demonstrated by cholinesterase staining, with visualization of the subneural apparatus. Neither metal binding nor cholinesterase activity was affected 4 weeks after dissection of the sciatic nerve, indicating that the metal binding site is postsynaptic. Freezing or formalin fixation of muscle prevented binding of all metal ions to the end plate without greatly affecting cholinesterase activity, indicating that these two activities of the end plate are distinct. Prior administration of acetylcholine, d-tubocurarine, neostigmine or diisopropyl fluorophosphate inhibited binding to the end plate of cadmium and zinc ions but did not alter binding of lead and stannous ions. By formation of a lake with alizarin red S previously injected in vivo intramuscularly, the release of calcium ions at the motor end plate following stimulation of the muscle through the nerve or administration of neostigmine was demonstrated. These results suggest a close relationship of the site of binding of divalent metal ions in the motor end plate to the site of calcium release, and a close but not identical relationship to the site of cholinesterase activity and the acetylcholine receptor.

scholarly journals Long-Chain Polyphosphate Causes Cell Lysis and Inhibits Bacillus cereus Septum Formation, Which Is Dependent on Divalent Cations

1999 ◽  
Vol 65 (9) ◽  
pp. 3942-3949 ◽  
Author(s):  
Simon K. Maier ◽  
Siegfried Scherer ◽  
Martin J. Loessner
Keyword(s):  
Cell Division ◽  
Metal Ions ◽  
Bacillus Cereus ◽  
Metal Ion ◽  
Divalent Cations ◽  
Divalent Metal ◽  
Divalent Metal Ions ◽  
Septum Formation ◽  
Cell Counts ◽  
Long Chain

ABSTRACT We investigated the cellular mechanisms that led to growth inhibition, morphological changes, and lysis of Bacillus cereus WSBC 10030 when it was challenged with a long-chain polyphosphate (polyP). At a concentration of 0.1% or higher, polyP had a bacteriocidal effect on log-phase cells, in which it induced rapid lysis and reductions in viable cell counts of up to 3 log units. The cellular debris consisted of empty cell wall cylinders and polar caps, suggesting that polyP-induced lysis was spatially specific. This activity was strictly dependent on active growth and cell division, since polyP failed to induce lysis in cells treated with chloramphenicol and in stationary-phase cells, which were, however, bacteriostatically inhibited by polyP. Similar observations were made with B. cereus spores; 0.1% polyP inhibited spore germination and outgrowth, and a higher concentration (1.0%) was even sporocidal. Supplemental divalent metal ions (Mg2+ and Ca2+) could almost completely block and reverse the antimicrobial activity of polyP; i.e., they could immediately stop lysis and reinitiate rapid cell division and multiplication. Interestingly, a sublethal polyP concentration (0.05%) led to the formation of elongated cells (average length, 70 μm) after 4 h of incubation. While DNA replication and chromosome segregation were undisturbed, electron microscopy revealed a complete lack of septum formation within the filaments. Exposure to divalent cations resulted in instantaneous formation and growth of ring-shaped edges of invaginating septal walls. After approximately 30 min, septation was complete, and cell division resumed. We frequently observed a minicell-like phenotype and other septation defects, which were probably due to hyperdivision activity after cation supplementation. We propose that polyP may have an effect on the ubiquitous bacterial cell division protein FtsZ, whose GTPase activity is known to be strictly dependent on divalent metal ions. It is tempting to speculate that polyP, because of its metal ion-chelating nature, indirectly blocks the dynamic formation (polymerization) of the Z ring, which would explain the aseptate phenotype.

In-situ modification of castor oil with divalent metal ions like Zn (II), Cu (II), Co (II) and Ba (II) and their comparative antioxidant study by in-vitro methods

2019 ◽  
Vol 284 ◽  
pp. 213-218 ◽  
Author(s):  
Md Ikbal Ahmed Talukdar ◽  
Md. Khursheed Akram ◽  
Taruna Singh ◽  
Manzoor A. Malik ◽  
Ovas A. Dar ◽  
...  
Keyword(s):  
Metal Ions ◽  
Castor Oil ◽  
Divalent Metal ◽  
Divalent Metal Ions ◽  
In Vitro Methods ◽  
In Situ Modification
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