Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.31.1 (micrococcal nuclease)
 2,818 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The molecular nature of the 'unconventional viruses' that cause slow, progressive brain deterioration is still poorly understood. As part of a reinvestigation of potential agent-specific nucleic acids, we developed a protocol for enriching agent-specific sequences. This protocol uses extensive micrococcal nuclease digestion followed by rate zonal sucrose sedimentation. Most of the infectivity in the gradient (84%) had a characteristic mean size of approximately 120S, and was resolved from 70% of a host glycoprotein (PrP) that can cosediment with infectivity. In infectious size fractions, nucleic acids were reduced approximately one million-fold with respect to starting brain homogenate, and specific purification of infectivity was approximately 100,000-fold with respect to nucleic acid. Using a novel polymerase chain reaction strategy, we were able to amplify RNA species in these fractions. Remarkably, host polyadenylated sequences of 1 to over 4 kb were detected in the nuclease-protected infectious fractions. These strategies set the stage for the identification of similar nucleic acids that may be specific for the CJD agent.
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PMID:Nuclease-resistant polyadenylated RNAs of significant size are detected by PCR in highly purified Creutzfeldt-Jakob disease preparations. 170 52

Representative preparations of partially purified Creutzfeldt-Jakob disease (CJD), including disaggregated density gradient fractions, were treated with a variety of nucleases. RNases as well as exhaustive digestions with micrococcal nuclease did not significantly diminish infectivity, but resulted in an approximately 7,000-fold specific purification of infectivity with respect to nucleic acid. Protected nucleic acids included species of up to 2,000 bases in length. After nuclease treatment, infectivity co-migrated with nucleic acid-protein complexes at a density of 1.27 g/cm3 in sucrose. Substantial specific protein purification were also achieved in the gradient step (approximately 11,000-fold), where 70% the host Gp34 ("prion protein") as well as other free proteins separated from infectivity. These CJD purifications are better than those previously attained in scrapie, and may be useful for further studies of non-host protein and nucleic acid species. The data are consistent with the hypothesis that CJD-like agents are composed of nucleic acid-protein complexes.
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PMID:Nuclease treatment results in high specific purification of Creutzfeldt-Jakob disease infectivity with a density characteristic of nucleic acid-protein complexes. 197 31

The molecular nature of the related infectious agents that cause Creutzfeldt-Jakob disease (CJD) and scrapie is poorly understood, and an agent-specific nucleic acid genome has not yet been identified. Several biological manifestations of these agents resemble those seen in retrovirus-induced diseases. We therefore attempted to identify an agent-specific retrovirus-like RNA transcript in CJD infectious fractions. A series of synthetic oligonucleotides complementary to known mammalian retroviral primer binding sites were used in a primer extension assay. Substrate nucleic acids isolated from partially purified hamster brain CJD infectious fractions and from parallel normal brain fractions were compared with total starting brain RNA. This sensitive exogenous strong-stop reaction revealed that CJD infectious fractions contained a series of potential retroviral RNAs including apparent transcripts of endogenous hamster IAP genes. Most transcripts selectively recovered in the fractions were substantially protected from micrococcal nuclease digestion, and at least one substrate RNA, consistent with an intracisternal A particle, was packaged in a form that had the same buoyant density as CJD infectivity. Although a completely CJD-specific transcript was not identified, the copurification of potential retroviral transcripts with CJD infectivity suggests that models of disease involving retrovirus-like nucleic acid elements deserve further consideration.
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PMID:Potential retroviral RNAs in Creutzfeldt-Jakob disease. 210 58