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Jerzy Ciesiołka

Publications and source records attributed to Jerzy Ciesiołka.

8 recordsLinked to original sources
PubMed2006

Inhibition of the catalytic activity of trans-acting antigenomic delta ribozyme by selected antibiotics and their Cu2+ complexes.

The effect of selected 10 antibiotics and their complexes with Cu(2+) ions on the catalytic activity of the trans-acting antigenomic delta ribozyme was investigated. Sisomicin, vancomycin, and actinomycin D displayed weak inhibitory properties. However, much stronger effects were detected with complexes of these antibiotics with Cu(2+) ions. The strongest inhibition was observed with actinomycin D-Cu(2+) complex, for which the calculated K(i) value was reduced ca. 35-fold upon metal ion complexation. We postulate that the antibiotic-Cu(2+) complexes are guided to the ribozyme metal ion binding site(s) presumably displacing the catalytically important metal ion(s). Moreover, we assume that, once positioned in appropriate distances to RNA phosphate groups and bases, the coordinated Cu(2+) ions become positively charged factors that enhance the affinity of the antibiotics to the ribozyme. These observations indicate that coordination of metal ions to antibiotics substantially changes their properties which might also have a biological relevance inside the cell.

Anti-Bacterial Agents↗
PubMed2006

Antigenomic delta ribozyme variants with mutations in the catalytic core obtained by the in vitro selection method.

We have used the in vitro selection method to search for catalytically active variants of the antigenomic delta ribozyme with mutations in the regions that constitute the ribozyme active site: L3, J1/4 and J4/2. In the initial combinatorial library 16 nt positions were randomized and the library contained a full representation of all possible sequences. Following ten cycles of selection-amplification several catalytically active ribozyme variants were identified. It turned out that one-third of the variants contained only single mutation G80U and their activity was similar to that of the wild-type ribozyme. Unexpectedly, in the next one-third of the variants the C76 residue, which was proposed to play a crucial role in the ribozyme cleavage mechanism, was mutated. In these variants, however, a cytosine residue was present in a neighboring position to the polynucleotide chain. It shows that the ribozyme catalytic core possesses substantial 'structural plasticity' and the capacity of functional adaptation. Four selected ribozyme variants were subjected to more detailed analysis. It turned out that the variants differed in their relative preferences towards Mg2+, Ca2+ and Mn2+ ions. Thus, the functional properties of the variants were dependent on both the structure of their catalytic sites and divalent metal ions performing catalysis.

Base Sequence↗
PubMed2006

[Structure and function of the non-coding regions of hepatitis C viral RNA].

At the 5' and 3' end of genomic HCV RNA there are two highly conserved, untranslated regions, 5'UTR and 3'UTR. These regions are organized into spatially ordered structures and they play key functions in regulation of processes of the viral life cycle. Most nucleotides of the region located at the 5' side of the coding sequence serve as an internal ribosomal entry site, IRES, which directs cap-independent translation. The RNA fragment present at the 3' end of the genome is required for virus replication and probably contributes to translation of viral proteins. During virus replication its genomic strand is transcribed into a strand of minus polarity, the replicative strand. Its 3' terminus is responsible for initiation of synthesis of descendant genomic strands. This article summarizes our current knowledge on the structure and function of the non-coding regions of hepatitis C genomic RNA, 5'UTR and 3'UTR, and the complementary sequences of the replicative viral strand.

3' Untranslated Regions↗
PubMed2005

tRNAPhe cleavage by aminoglycosides is triggered off by formation of an abasic site.

This communication reports the characteristics of the mechanism of highly specific tRNA(Phe) cleavage, which occurs in the anticodon loop in the presence of aminoglycoside antibiotic-neomycin B. The data prove that the cleavage requires previous depurination of the polynucleotide chain at position 37, which is occupied by a hypermodified guanine base-wybutine. The results suggest that the phenomenon, previously considered as selective with respect to the presence of tRNA hypermodification, may concern far more RNA molecules, namely the ones carrying abasic sites.

Anti-Bacterial Agents↗
PubMed2004

Generating in vitro transcripts with homogenous 3' ends using trans-acting antigenomic delta ribozyme.

In most in vitro run-off transcription reactions with T7 RNA polymerase, transcripts with heterogeneous ends are commonly obtained. Towards the goal of finding a simple and effective procedure for correct processing of their 3' ends we propose the use of trans-acting antigenomic delta ribozyme. We demonstrate that the extension of nascent transcripts with only seven nucleotides complementary to the ribozyme's recognition site, and subsequently, the removal of those nucleotides with the ribozyme acting in trans, is an efficient procedure for generating transcripts with homogenous 3' ends. This approach was tested on two model RNA molecules: an in vitro transcript of yeast tRNA(Phe) and a delta ribozyme, which processed itself during transcription. The proposed procedure is a simple alternative to the use of ribozymes as cis-cleaving autocatalytic cassettes attached to transcript 3' ends. As there is little possibility that the required additional stretch, only seven nucleotides long, enters into stable interactions with other parts of the transcripts, it can be cleaved off with high efficacy.

Base Sequence↗
PubMed2003

In vitro oxidative activity of cupric complexes of kanamycin A in comparison to in vivo bactericidal efficacy.

The interactions of copper(II) complexes of kanamycin A with oxidation-susceptible biomolecules: 2'-deoxyguanosine, plasmid DNA and yeast tRNA(Phe) were studied in both the presence and absence of hydrogen peroxide. The mixture of complex with H(2)O(2) was found to be an efficient oxidant, converting dG to its 8-oxo derivative, generating strand breaks in plasmid DNA and multiple cleavages in tRNA(Phe). Some of these reactions may play a role in toxic effects of aminoglycoside antibiotics. These complexes were screened for their antibacterial activity. The microbiological studies undertaken to compare the bactericidal action of kanamycin A alone and complexed with copper(II) ions in both neutral and oxidative environment revealed that the enhancement of bactericidal action by Cu(II) was not statistically significant.

Anti-Bacterial Agents↗
PubMed2002

DNA and RNA damage by Cu(II)-amikacin complex.

The oxidation-promoting reactivity of copper(II) complex of aminoglycosidic antibiotic amikacin [Cu(II)-Ami] in the presence of hydrogen peroxide, was studied at pH 7.4, using 2'-deoxyguanosine (dG), pBR322 plasmid DNA and yeast tRNAPhe as target molecules. The mixtures of complex with H2O2 were found to be efficient oxidants, converting dG to its 8-oxo derivative, generating strand breaks in plasmid DNA and multiple cleavages in tRNAPhe. The complex underwent autooxidation as well, with amikacin hydroperoxides as likely major products. This reactivity pattern was found to be due to a combination of metal-bound and free hydroxyl radicals.

8-Hydroxy-2'-Deoxyguanosine↗