The oligoadenylate synthetase-ribonuclease L pathway is a major player in the interferon-induced antiviral defense mechanism of cells. Upon sensing viral dsRNA, 5'-phosphorylated 2',5'-oligoadenylates are synthesized, and subsequently activate latent RNase L. To determine the influence of 5'-phosphate end on the activation of human RNase L, four sets of 5'-phosphonate modified oligoadenylates were prepared on solid-phase. The ability of these 5'-modified oligoadenylates bearing shortened, isosteric and prolonged phosphonate linkages to activate RNase L was explored. We found that isosteric linkages and linkages prolonged by one atom were in general well tolerated by the enzyme with the EC50 values comparable to that of the natural activator. In contrast, linkages shortened by one atom or prolonged by two atoms exhibited decrease in the activity.
- MeSH
- adeninnukleotidy chemická syntéza chemie farmakologie MeSH
- endoribonukleasy metabolismus MeSH
- konformace nukleové kyseliny MeSH
- lidé MeSH
- oligoribonukleotidy chemická syntéza chemie farmakologie MeSH
- organofosfonáty chemická syntéza chemie farmakologie MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
While alarmone nucleotides guanosine-3',5'-bisdiphosphate (ppGpp) and guanosine-5'-triphosphate-3'-diphosphate (pppGpp) are archetypical bacterial second messengers, their adenosine analogues ppApp (adenosine-3',5'-bisdiphosphate) and pppApp (adenosine-5'-triphosphate-3'-diphosphate) are toxic effectors that abrogate bacterial growth. The alarmones are both synthesized and degraded by the members of the RelA-SpoT Homologue (RSH) enzyme family. Because of the chemical and enzymatic liability of (p)ppGpp and (p)ppApp, these alarmones are prone to degradation during structural biology experiments. To overcome this limitation, we have established an efficient and straightforward procedure for synthesizing nonhydrolysable (p)ppNuNpp analogues starting from 3'-azido-3'-deoxyribonucleotides as key intermediates. To demonstrate the utility of (p)ppGNpp as a molecular tool, we show that (i) as an HD substrate mimic, ppGNpp competes with ppGpp to inhibit the enzymatic activity of human MESH1 Small Alarmone Hyrolase, SAH; and (ii) mimicking the allosteric effects of (p)ppGpp, (p)ppGNpp acts as a positive regulator of the synthetase activity of long ribosome-associated RSHs Rel and RelA. Finally, by solving the structure of the N-terminal domain region (NTD) of T. thermophilus Rel complexed with pppGNpp, we show that as an HD substrate mimic, the analogue serves as a bona fide orthosteric regulator that promotes the same intra-NTD structural rearrangements as the native substrate.
- MeSH
- adeninnukleotidy chemická syntéza metabolismus MeSH
- alosterické místo MeSH
- Bacillus subtilis MeSH
- bakteriální proteiny metabolismus MeSH
- deoxyribonukleotidy MeSH
- Escherichia coli MeSH
- konformace proteinů MeSH
- ligasy metabolismus MeSH
- pyrofosfatasy metabolismus MeSH
- regulace genové exprese u bakterií účinky léků MeSH
- vazba proteinů MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The method was developed for the synthesis of biologically important adenosine phosphates, AMP, cAMP and ATP modified with p-carborane cluster - a highly lipophilic pharmacophore. The adenosine phosphates modified with p-carborane are characterized by increased stability in human blood plasma and much more higher lipophilicity than that of the unmodified phosphates. ATP analog 4 bearing p-carborane cluster is not a Taq polymerase substrate and most probably not the polymerase inhibitor. These properties may have clinical implications.
To determine the influence of methylene group insertion in the internucleotide linkage on the binding process of 2',5'-oligoadenylates to RNase L, a series of 2'-phosphonate-modified trimers and tetramers were synthesized from appropriate monomeric units and evaluated for their ability to bind to murine RNase L. Tetramers pAAXA modified by ribo-, arabino-, or xylo-2'-phosphonate unit X in the third position were capable of binding to RNase L in nanomolar concentrations. The replacement of the first residue (pXAAA), or both the first and the third residues (pXAXA), was also tolerated by the enzyme. In contrast, in all cases, the replacement of the second residue (pAXAA) resulted in the significant decrease of binding ability. Additionally, no more than two phosphonate modifications in the tetramer were allowed to retain the binding affinity to the enzyme. Although all three tetramers pAAXA were found to be potent enzyme binders, only tetramers modified by ribo- and xylo-2'-phosphonate unit X activated the RNase L-catalyzed cleavage of the RNA substrate. Surprisingly, tetramer pAAXA, modified by arabino-2'-phosphonate unit X, did not activate the enzyme and can be considered a potent antagonist. In comparison with their natural counterpart, the phosphonate analogues of the pA4 exhibit superior resistance toward nucleases present in the murine spleen homogenate.
- MeSH
- adeninnukleotidy farmakologie chemická syntéza chemie MeSH
- endoribonukleasy metabolismus MeSH
- financování organizované MeSH
- myši inbrední BALB C MeSH
- myši MeSH
- oligoribonukleotidy farmakologie chemická syntéza chemie MeSH
- organofosfonáty farmakologie chemická syntéza chemie MeSH
- slezina enzymologie MeSH
- stereoizomerie MeSH
- vazba proteinů MeSH
- vztahy mezi strukturou a aktivitou MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- techniky in vitro MeSH
