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C Richardson - One of the best experts on this subject based on the ideXlab platform.
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zinc binding domain of the bacteriophage t7 dna primase modulates binding to the dna template
Journal of Biological Chemistry, 2012Co-Authors: Barak Akabayov, C RichardsonAbstract:The zinc-binding domain (ZBD) of prokaryotic DNA primases has been postulated to be crucial for recognition of specific sequences in the single-stranded DNA template. To determine the molecular basis for this role in recognition, we carried out homolog-scanning mutagenesis of the zinc-binding domain of DNA primase of bacteriophage T7 using a bacterial homolog from Geobacillus stearothermophilus. The ability of T7 DNA primase to catalyze template-directed Oligoribonucleotide synthesis is eliminated by substitution of any five-amino acid residue-long segment within the ZBD. The most significant defect occurs upon substitution of a region (Pro-16 to Cys-20) spanning two cysteines that coordinate the zinc ion. The role of this region in primase function was further investigated by generating a protein library composed of multiple amino acid substitutions for Pro-16, Asp-18, and Asn-19 followed by genetic screening for functional proteins. Examination of proteins selected from the screening reveals no change in sequence-specific recognition. However, the more positively charged residues in the region facilitate DNA binding, leading to more efficient Oligoribonucleotide synthesis on short templates. The results suggest that the zinc-binding mode alone is not responsible for sequence recognition, but rather its interaction with the RNA polymerase domain is critical for DNA binding and for sequence recognition. Consequently, any alteration in the ZBD that disturbs its conformation leads to loss of DNA-dependent Oligoribonucleotide synthesis.
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acidic residues in the nucleotide binding site of the bacteriophage t7 dna primase
Journal of Biological Chemistry, 2005Co-Authors: C RichardsonAbstract:Abstract DNA primases catalyze the synthesis of Oligoribonucleotides to initiate lagging strand DNA synthesis during DNA replication. Like other prokaryotic homologs, the primase domain of the gene 4 helicase-primase of bacteriophage T7 contains a zinc motif and a catalytic core. Upon recognition of the sequence, 5′-GTC-3′ by the zinc motif, the catalytic site condenses the cognate nucleotides to produce a primer. The TOPRIM domain in the catalytic site contains several charged residues presumably involved in catalysis. Each of eight acidic residues in this region was replaced with alanine, and the properties of the altered primases were examined. Six of the eight residues (Glu-157, Glu-159, Asp-161, Asp-207, Asp-209, and Asp-237) are essential in that altered gene 4 proteins containing these mutations cannot complement T7 phage lacking gene 4 for T7 growth. These six altered gene 4 proteins can neither synthesize primers de novo nor extend an Oligoribonucleotide. Despite the inability to catalyze phosphodiester bond formation, the altered proteins recognize the sequence 5′-GTC-3′ in the template and deliver preformed primer to T7 DNA polymerase. The alterations in the TOPRIM domain result in the loss of binding affinity for ATP as measured by surface plasmon resonance assay together with ATP-agarose affinity chromatography.
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essential lysine residues in the rna polymerase domain of the gene 4 primase helicase of bacteriophage t7
Journal of Biological Chemistry, 2001Co-Authors: C RichardsonAbstract:Abstract At a replication fork DNA primase synthesizes Oligoribonucleotides that serve as primers for the lagging strand DNA polymerase. In the bacteriophage T7 replication system, DNA primase is encoded by gene 4 of the phage. The 63-kDa gene 4 protein is composed of two major domains, a helicase domain and a primase domain located in the C- and N-terminal halves of the protein, respectively. T7 DNA primase recognizes the sequence 5′-NNGTC-3′ via a zinc motif and catalyzes the template-directed synthesis of tetraribonucleotides pppACNN. T7 DNA primase, like other primases, shares limited homology with DNA-dependent RNA polymerases. To identify the catalytic core of the T7 DNA primase, single-point mutations were introduced into a basic region that shares sequence homology with RNA polymerases. The genetically altered gene 4 proteins were examined for their ability to support phage growth, to synthesize functional primers, and to recognize primase recognition sites. Two lysine residues, Lys-122 and Lys-128, are essential for phage growth. The two residues play a key role in the synthesis of phosphodiester bonds but are not involved in other activities mediated by the protein. The altered primases are unable to either synthesize or extend an Oligoribonucleotide. However, the altered primases do recognize the primase recognition sequence, anneal an exogenous primer 5′-ACCC-3′ at the site, and transfer the primer to T7 DNA polymerase. Other lysines in the vicinity are not essential for the synthesis of primers.
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characterization of a novel dna primase from the salmonella typhimurium bacteriophage sp6
Biochemistry, 2000Co-Authors: Timothy Y Tseng, David N Frick, C RichardsonAbstract:The gene for the DNA primase encoded by Salmonella typhimurium bacteriophage SP6 has been cloned and expressed in Escherichia coli and its 74-kDa protein product purified to homogeneity. The SP6 primase is a DNA-dependent RNA polymerase that synthesizes short Oligoribonucleotides containing each of the four canonical ribonucleotides. GTP and CTP are both required for the initiation of Oligoribonucleotide synthesis. In reactions containing only GTP and CTP, SP6 primase incorporates GTP at the 5‘-end of Oligoribonucleotides and CMP at the second position. On synthetic DNA templates, pppGpC dinucleotides are synthesized most rapidly in the presence of the sequence 5‘-GCA-3‘. This trinucleotide sequence, containing a cryptic dA at the 3‘-end, differs from other known bacterial and phage primase recognition sites. SP6 primase shares some properties with the well-characterized E. coli bacteriophage T7 primase. The T7 DNA polymerase can use Oligoribonucleotides synthesized by SP6 primase as primers for DNA synth...
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interaction of bacteriophage t7 gene 4 primase with its template recognition site
Journal of Biological Chemistry, 1999Co-Authors: David N Frick, C RichardsonAbstract:Abstract The primase fragment of the bacteriophage T7 63-kDa gene 4 helicase/primase protein contains the 271 N-terminal amino acid residues and lacks helicase activity. The primase fragment catalyzes the synthesis of Oligoribonucleotides at rates similar to those catalyzed by the full-length protein in the presence of a 5-nucleotide DNA template containing a primase recognition site (5′-GGGTC-3′, 5′-TGGTC-3′, 5′-GTGTC-3′, or 5′-TTGTC-3′). Although it is not copied into the Oligoribonucleotides, the cytosine at the 3′-position is essential for synthesis and template binding. Two nucleotides flanking the 3′-end of the recognition site are required for tight DNA binding and rapid Oligoribonucleotide synthesis. Nucleotides added to the 5′-end have no effect on the rate of Oligoribonucleotide synthesis or the affinity of the primase for DNA. The binding of either ATP or CTP significantly increases the affinity of the primase for its DNA template. DNA lacking a primase recognition site does not inhibit Oligoribonucleotide synthesis, suggesting that the primase binds DNA in a sequence-specific manner. The affinity of the primase for templates is weak, ranging from 10 to 150 μm. The tight DNA binding (<1 μm) observed with the 63-kDa gene 4 protein occurs viainteractions between DNA templates and the helicase domain.
Shuang Tang - One of the best experts on this subject based on the ideXlab platform.
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nonspecific deadenylation on sarcin ricin domain rna catalyzed by gelonin under acidic conditions
Archives of Biochemistry and Biophysics, 2002Co-Authors: Shuang Tang, Wang-yi Liu, Fiorenzo StirpeAbstract:Gelonin is a single-chain ribosome-inactivating protein that can hydrolyze the glycosidic bond of a highly conserved adenosine residue in the sarcin/ricin domain (SRD) of the largest RNA in ribosome and thus irreversibly inhibit protein synthesis. Recently, the specificity in substrate recognition was challenged by the fact that gelonin could remove adenines from some other Oligoribonucleotide substrates. However, the site specificity of gelonin to deadenylate various substrates were unknown. Hereby, the effect of pH values upon site specificity of the deadenylation activity of gelonin was studied using the synthetic Oligoribonucleotide (named SRD RNA) that mimicked the ribosomal SRD. Interestingly, gelonin gradually acquired the ability to nonspecifically remove adenines from SRD RNA when pH values changed from neutral to acidic conditions. Another two SRD RNA mutants, either with the conserved adenosine deleted or with the tetraloop converted, showed very similar cleavage style to wild-type SRD RNA, underscoring the important role of pH value in site specificity of recognition by gelonin. Furthermore, the RNA N-glycosidase activity of gelonin was also enhanced with the decreasing of pH values. In addition, no obvious change was observed in the molecular conformation of gelonin at various pH values. Taken together, our data implied that the protonation of adenosines in SRD RNA was potentially an important factor for the nonspecific deadenlyation by gelonin.
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In vitro interaction of eukaryotic elongation factor 2 with synthetic Oligoribonucleotide that mimics GTPase domain of rat 28S ribosomal RNA.
The International Journal of Biochemistry & Cell Biology, 2002Co-Authors: Shuang Tang, Wang-yi LiuAbstract:Eukaryotic elongation factor 2 (eEF2) catalyzed the translocation of peptidyl-tRNA from the ribosomal A site to the P site. In this paper, the interaction between eEF2 and GTD RNA, a synthetic Oligoribonucleotide that mimicked the GTPase domain of rat 28S ribosomal RNA, was studied in vitro. The purified eEF2 could bind to GTD RNA, forming a stable complex. Transfer RNA competed with GTD RNA in binding to eEF2, whereas poly(A), poly(U) and poly(I, C) did not interfere with the interaction between eEF2 and GTD RNA, demonstrating that the tertiary structure of RNA might be necessary for the recognition of and binding to eEF2. The complex formation of eEF2 with GTD RNA was inhibited by SRD RNA, a synthetic Oligoribonucleotide mimic of Sarcin/Ricin domain RNA of rat 28S RNA. Similarly, GTD RNA inhibited the interaction between eEF2 and SRD RNA. This fact implies that these small Oligoribonucleotides probably share similar recognition or binding identity elements in their tertiary structures. In addition, the binding of eEF2 to GTD RNA could be obviously weakened by the ADP-ribosylation of eEF2 with diphtheria toxin. These results indicate that eEF2 behaves differently from prokaryotic EF-G in binding to ribosomal RNA.
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eukaryotic elongation factor 2 can bind to the synthetic Oligoribonucleotide that mimics sarcin ricin domain of rat 28s ribosomal rna
Molecular and Cellular Biochemistry, 2001Co-Authors: Shuang Tang, Wang-yi Liu, Kang-cheng RuanAbstract:Eukaryotic elongation factor 2 (eEF2) catalyzes the translocation of peptidyl-tRNA from the A site to P site by binding to the ribosome. In this work, the complex formation of rat liver eEF2 with a synthetic Oligoribonucleotide (SRD RNA) that mimics sarcin/ricin domain of rat 28S ribosomal RNA is invested in vitro. Purified eEF2 can specifically bind SRD RNA to form a stable complex. tRNA competes with SRD RNA in binding to eEF2 in a less extent. Pretreatment of eEF2 with GDP or ADP-ribosylation of eEF2 by diphtheria toxin can obviously reduce the ability of eEF2 to form the complex with the synthetic Oligoribonucleotide. These results indicate that eEF2 is likely to bind directly to the sarcin/ricin domain of 28S ribosomal RNA in the process of protein synthesis.
Wang-yi Liu - One of the best experts on this subject based on the ideXlab platform.
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nonspecific deadenylation on sarcin ricin domain rna catalyzed by gelonin under acidic conditions
Archives of Biochemistry and Biophysics, 2002Co-Authors: Shuang Tang, Wang-yi Liu, Fiorenzo StirpeAbstract:Gelonin is a single-chain ribosome-inactivating protein that can hydrolyze the glycosidic bond of a highly conserved adenosine residue in the sarcin/ricin domain (SRD) of the largest RNA in ribosome and thus irreversibly inhibit protein synthesis. Recently, the specificity in substrate recognition was challenged by the fact that gelonin could remove adenines from some other Oligoribonucleotide substrates. However, the site specificity of gelonin to deadenylate various substrates were unknown. Hereby, the effect of pH values upon site specificity of the deadenylation activity of gelonin was studied using the synthetic Oligoribonucleotide (named SRD RNA) that mimicked the ribosomal SRD. Interestingly, gelonin gradually acquired the ability to nonspecifically remove adenines from SRD RNA when pH values changed from neutral to acidic conditions. Another two SRD RNA mutants, either with the conserved adenosine deleted or with the tetraloop converted, showed very similar cleavage style to wild-type SRD RNA, underscoring the important role of pH value in site specificity of recognition by gelonin. Furthermore, the RNA N-glycosidase activity of gelonin was also enhanced with the decreasing of pH values. In addition, no obvious change was observed in the molecular conformation of gelonin at various pH values. Taken together, our data implied that the protonation of adenosines in SRD RNA was potentially an important factor for the nonspecific deadenlyation by gelonin.
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In vitro interaction of eukaryotic elongation factor 2 with synthetic Oligoribonucleotide that mimics GTPase domain of rat 28S ribosomal RNA.
The International Journal of Biochemistry & Cell Biology, 2002Co-Authors: Shuang Tang, Wang-yi LiuAbstract:Eukaryotic elongation factor 2 (eEF2) catalyzed the translocation of peptidyl-tRNA from the ribosomal A site to the P site. In this paper, the interaction between eEF2 and GTD RNA, a synthetic Oligoribonucleotide that mimicked the GTPase domain of rat 28S ribosomal RNA, was studied in vitro. The purified eEF2 could bind to GTD RNA, forming a stable complex. Transfer RNA competed with GTD RNA in binding to eEF2, whereas poly(A), poly(U) and poly(I, C) did not interfere with the interaction between eEF2 and GTD RNA, demonstrating that the tertiary structure of RNA might be necessary for the recognition of and binding to eEF2. The complex formation of eEF2 with GTD RNA was inhibited by SRD RNA, a synthetic Oligoribonucleotide mimic of Sarcin/Ricin domain RNA of rat 28S RNA. Similarly, GTD RNA inhibited the interaction between eEF2 and SRD RNA. This fact implies that these small Oligoribonucleotides probably share similar recognition or binding identity elements in their tertiary structures. In addition, the binding of eEF2 to GTD RNA could be obviously weakened by the ADP-ribosylation of eEF2 with diphtheria toxin. These results indicate that eEF2 behaves differently from prokaryotic EF-G in binding to ribosomal RNA.
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eukaryotic elongation factor 2 can bind to the synthetic Oligoribonucleotide that mimics sarcin ricin domain of rat 28s ribosomal rna
Molecular and Cellular Biochemistry, 2001Co-Authors: Shuang Tang, Wang-yi Liu, Kang-cheng RuanAbstract:Eukaryotic elongation factor 2 (eEF2) catalyzes the translocation of peptidyl-tRNA from the A site to P site by binding to the ribosome. In this work, the complex formation of rat liver eEF2 with a synthetic Oligoribonucleotide (SRD RNA) that mimics sarcin/ricin domain of rat 28S ribosomal RNA is invested in vitro. Purified eEF2 can specifically bind SRD RNA to form a stable complex. tRNA competes with SRD RNA in binding to eEF2 in a less extent. Pretreatment of eEF2 with GDP or ADP-ribosylation of eEF2 by diphtheria toxin can obviously reduce the ability of eEF2 to form the complex with the synthetic Oligoribonucleotide. These results indicate that eEF2 is likely to bind directly to the sarcin/ricin domain of 28S ribosomal RNA in the process of protein synthesis.
Ira G Wool - One of the best experts on this subject based on the ideXlab platform.
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a determination of the identity elements in yeast 18 s ribosomal rna for the recognition of ribosomal protein ys11 the role of the kink turn motif in helix 11
Journal of Molecular Biology, 2005Co-Authors: John Dresios, Yuenling Chan, Ira G WoolAbstract:A description of the site of interaction of YS11, the yeast homolog of eubacterial S17, with 18 S rRNA was obtained by assessing the binding of the ribosomal protein, in a filter retention assay, to Oligoribonucleotides that reproduce regions of 18 S rRNA. YS11 binds predominantly to domain I; the Kd value is 113 nM. The dimensions of the YS11 binding site were refined, guided by chemical protection data and by the atomic structure of the Thermus thermophilus 30 S subunit, which has the S17 recognition site in 16 S rRNA. An Oligoribonucleotide that mimics helix 11, a phylogenetically conserved region in domain I, binds YS11 with a Kd value of 230 nM; a second Oligoribonucleotide that contains only the kink-turn motif in helix 11 binds YS11 with a Kd value of 528 nM. Thus, helix 11 has most of the nucleotides required for the recognition of YS11. To identify those nucleotides a set of 27 transversion mutations in H11 was constructed and their contribution to the binding of YS11 determined. Mutations of nine nucleotides (U313, C314, A316, G337, C338, G347, U348, U350, and C351) increased the Kd value for YS11 binding by at least eightfold; G325U and U349A mutations increased the Kd value fivefold. Eight of the 11 mutations are in the kink–turn in H11, confirming the critical importance of the motif for YS11 recognition. The other three nucleotides are in the lower stem and the terminal loop of H11, which makes a lesser, but still important, contribution to YS11 binding. The identity elements for YS11 recognition are: A316, G325, G337, G347, U348, U349, U350, and C351. The effect of the other nucleotides that decrease binding is probably indirect, presumably they affect the conformation of the binding site but do not have contacts to YS11 amino acid residues. The eight identity element nucleotides are in regions of H11 that deviate from A-form geometry and the contacts are predominantly, if not exclusively, to backbone phosphate and sugar oxygen atoms, indicating that YS11 recognizes the shape of the rRNA binding site rather than reading the sequence of nucleotides.
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the ribosome in pieces binding of elongation factor ef g to Oligoribonucleotides that mimic the sarcin ricin and thiostrepton domains of 23s ribosomal rna
Proceedings of the National Academy of Sciences of the United States of America, 1997Co-Authors: Alexander Munishkin, Ira G WoolAbstract:An Oligoribonucleotide (a 27-mer) that mimics the sarcin/ricin (S/R) domain of Escherichia coli 23S rRNA binds elongation factor EF-G; the Kd is 6.9 μM, whereas for binding to ribosomes it is 0.7 μM. Binding saturates when EF-G and the S/R RNA are equimolar; at saturation 70% of the input RNA is in complexes with EF-G. Binding of EF-G to S/R RNA does not require GTP but is inhibited by GDP; the inhibition by GDP is overcome by GTP. The effects of mutations of the S/R domain nucleotides G2655, A2660, and G2661 suggest that EF-G recognizes the conformation of the RNA rather than the identity of the nucleotides. EF-G also binds to an Oligoribonucleotide (an 84-mer) that has the thiostrepton region of 23S rRNA; however, EF-G binds independently to S/R and thiostrepton Oligoribonucleotides.
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dependence of depurination of Oligoribonucleotides by ricin a chain on divalent cations and chelating agents
Iubmb Life, 1996Co-Authors: Anton Gluck, Ira G WoolAbstract:: Ricin A-chain is a cytotoxic RNA N-glycosidase that inactivates eukaryotic ribosomes by depurinating the adenosine at position 4324 in 28S rRNA. The enzyme retains its specificity when a synthetic Oligoribonucleotide (a 35-mer) that mimics the structure at the site of action is the substrate. However, covalent modification by ricin A-chain of the Oligoribonucleotide but not of ribosomes, depends on the simultaneous presence of a divalent cation and a chelating agent.
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ribosomal rna identity elements for ricin a chain recognition and catalysis
Journal of Molecular Biology, 1991Co-Authors: Y Endo, Anton Gluck, Ira G WoolAbstract:Ricin is a cytotoxic protein that inactivates ribosomes by hydrolyzing the N-glycosidic bond between the base and the ribose at position A4324 in eukaryotic 28 S rRNA. The requirements for the recognition by ricin A-chain of this nucleotide and for the catalysis of cleavage were examined using a synthetic Oligoribonucleotide that reproduces the sequence and the secondary structure of the RNA domain (a helical stem, a bulged nucleotide, and a 17-member single-stranded loop). The wild-type RNA (35mer) and a number of mutants were transcribed in vitro from synthetic DNA templates with phage T7 RNA polymerase. With the wild-type Oligoribonucleotide the ricin A-chain catalyzed reaction has a Km of 13.55 microM and a Kcat of 0.023 min-1. Recognition and catalysis by ricin A-chain has an absolute requirement for A at the position that corresponds to 4324. The helical stem is also essential; however, the number of base-pairs can be reduced from the seven found in 28 S rRNA to three without loss of identity. The nature of these base-pairs can affect catalysis. A change of the second set from one canonical (G.C) to another (U.A) reduces sensitivity to ricin A-chain; whereas, a change of the third pair (U.A----G.C) produces supersensitivity. The bulged nucleotide does not contribute to identification. Hydrolysis is affected by altering the nucleotides in the universal sequence surrounding A4324 or by changing the position in the loop of the tetranucleotide GA(ricin)GA: all of these mutants have a null phenotype. If ribosomes are treated first with alpha-sarcin to cleave the phosphodiester bond at G4325 ricin can still catalyze depurination at A4324. This implies that cleavage by alpha-sarcin at the center of what has been presumed to be a 17 nucleotide single-stranded loop in 28 S rRNA produces ends that are constrained in some way. On the other hand, hydrolysis by alpha-sarcin of the corresponding position in the synthetic Oligoribonucleotide prevents recognition by ricin A-chain. The results suggest that the loop has a complex structure, affected by ribosomal proteins, and this bears on the function in protein synthesis of the alpha-sarcin/ricin rRNA domain.
Sergei M Gryaznov - One of the best experts on this subject based on the ideXlab platform.
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synthesis and properties of rna analogs Oligoribonucleotide n3 p5 phosphoramidates
Nucleic Acids Research, 1999Co-Authors: Tracy Matray, Sergei M GryaznovAbstract:The synthesis and characterization of RNA mimetics, uniformly modified Oligoribonucleotide N3'-->P5' phosphoramidates containing all four natural bases (uracil, cytosine, adenine and guanine) as well as thymidine and 2,6-diaminopurine, are described. These RNA analogs contain N3'-->P5' phosphoramidate internucleotide linkages which replaced natural RNA O3'-->P5' phosphodiester groups. These oligonucleo-tides were constructed from novel monomeric units (2'- t -butyldimethylsilyl)-3'-(monomethoxyltrityl)-amino-nucleoside-5'- phos phoramidites, the preparation of which is also presented. Several mixed base 9-13mer Oligoribonucleotide phosphoramidates were synthesized with step-wise coupling yields of 96-98%. Thermal denaturation experiments demonstrated that ribo-N3'-->P5' phosphoramidates form stable duplexes with a complementary RNA strand. Thus, the melting temperature ( T (m)) of a duplex formed by a 13mer ribo-N3'-->P5' phosphoramidate (84 degrees C) was higher than that observed for the isosequential natural RNA oligomer (64.0 degrees C), or for the 2'-deoxy-N3'-->P5' phosphoramidate counterpart (71.7 degrees C). Moreover, substitution of adenine by 2, 6-diaminopurine in an oligoribophosphoramidate pentamer resulted in a very significant increase in the duplex melting temperature ( approximately 7 degrees C per base substitution). The RNA phosphoramidates also showed similar rates of hydrolysis by both RNase A and RNase T(1)as compared to natural RNA oligomers. The data presented indicate that this class of RNA analogs may be used as structural and functional RNA mimetics.
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rna mimetics Oligoribonucleotide n3 p5 phosphoramidates
Nucleic Acids Research, 1998Co-Authors: Sergei M Gryaznov, Holger WinterAbstract:The synthesis and properties of novel RNA mimetics, Oligoribonucleotide N3'-->P5' phosphoramidates, are described. These oligonucleotides contain 3'-aminoribonucleosides connected via N3'-->P5' phosphoramidate linkages, replacing the native RNA O3'-->P5' phosphodiester counterparts. The key monomers 2'-t-butyldimethylsilyl-3'-(monomethoxytrityl)-amino-5'-phospho ramidi tes were synthesized and used to prepare the oligonucleotide phosphoramidates using a solid phase methodology based on the phosphoramidite transfer reaction. Oligoribophosphoramidates are very resistant to enzymatic hydrolysis by snake venom phosphodiesterase. These compounds form stable duplexes with complementary natural phosphodiester DNA and RNA strands, as well as with 2'-deoxy N3'-->P5' phosphoramidates. The increase in melting temperature, Delta T m, was 5-14 degrees C relative to the 2'-deoxy phosphoramidates for decanucleotides. Also, the thermal stability of the ribophosphoramidatehomoduplex was noticeably higher (Delta T m +9.5 degrees C) than that for the isosequential 2'-deoxy phosphoramidate complex. Furthermore, the oligopyrimidine ribo N3'-->P5' phosphoramidate formed an extremely stable triplex with an oligopurine/oligopyrimidine DNA duplex with Delta T m +14.3 degrees C relative to the 2'-deoxy N3'-->P5' phosphoramidate counterpart. The properties of the Oligoribonucleotide N3'-->P5' phosphoramidates indicate that these compounds can be used as hydrolytically stable structural and functional RNA mimetics.
