Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Peptide nucleic acids (PNAs) are a powerful tool for recognition of double-stranded DNA. Strand invasion is most efficient when pyrimidine PNAs are linked to form a bisPNA in which one strand binds by Watson-Crick base pairing while the other binds by Hoogsteen base pairing to the newly formed PNA-DNA duplex. Within many genes, however, polypyrimidine target sequences may not be located in optimal positions relative to transcription factor binding sites, and this deficiency may complicate attempts to identify potent antigene PNAs. To increase the versatility of strand invasion by PNAs, we have synthesized bisPNAs and bisPNA-peptide conjugates containing a mixed base extension of the Watson-Crick polypyrimidine strand. We find that these tail-clamp PNAs (TC-PNAs) bind duplex DNA and inhibit transcription. DNA recognition occurs with single-stranded or TC-bisPNAs and requires attachment of positively charged amino acids. Association rate constants, k(a), for binding to DNA by TC-PNAs are as high as 35000 M(-1) s(-1) and are usually only a fewfold lower than for analogous PNAs that lack mixed base extensions. The ability to bind duplex DNA is not always necessary for inhibition of transcription, possibly because PNAs can bind to accessible DNA within the transcription bubble created by RNA polymerase. These results, together with similar findings independently obtained by Nielsen and colleagues [Bentin, T., Larsen, H. J., and Nielsen, P. E. (2003) Biochemistry 42, 13987-13995], expand the range of sequences within duplex DNA that are accessible to PNAs and suggest that TC-PNA-peptide conjugates are good candidates for further testing as antigene agents.
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PMID:Extending recognition by peptide nucleic acids (PNAs): binding to duplex DNA and inhibition of transcription by tail-clamp PNA-peptide conjugates. 1463 68

Approximately 5,000 ha of processing peas (Pisum sativum L) are cultivated annually in the Po River Valley of northern Italy. During the 1998 growing season, affected pea plants in this region were observed that exhibited mild chlorosis and mottling, leaf rolling, and stunting symptoms. High aphid populations and disease levels of nearly 100% were observed in susceptible varieties. Samples from affected fields were analyzed for the presence of bean leafroll virus (BLRV). Nonviruliferous pea aphids (Acyrthosiphon pisum Harris) received a 48-h acquisition access period on symptomatic leaves. Aphids were then transferred to Puget pea and Diana faba bean for a 72-h inoculation access period. Leaf samples were also macerated in 0.05 M potassium phosphate pH 7.4, and inoculated mechanically to pea, faba bean, chickpea (Cicer arietinum L.), Chenopodium quinoa Willd., and C. amaranticolor Coste & Reyn. Symptoms typical of those observed in the original field plants appeared 10 to 14 days after aphid transmissions in both pea and faba bean inoculated with pea aphids. No symptoms were observed in any of the hosts that were inoculated mechanically. Total nucleic acid extracts from the original pea samples, and from leaf tissue of pea and faba bean plants inoculated with aphids, served as templates in reverse-transcriptase polymerase chain reaction assays. Primers BLR-V157 and BLR-C546, which flanked a 400-bp fragment, were designed with available sequence data for the coat protein gene of BLRV (1). An amplification product of the expected size was generated from symptomatic plants but not from healthy controls. Sequence analysis of the cloned fragments revealed a 99% nucleic acid homology with the published sequence for BLRV and an isolate obtained from alfalfa in Washington State (R. Larsen, unpublished). This is the first report of BLRV in Italy. Reference: (1) B. Brill et al. Nucleic Acids Res. 18:5544, 1990.
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PMID:First Report of Bean Leafroll Luteovirus Infecting Pea in Italy. 3084 4