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)

Nuclear Dictyostelium discoideum RNase P was subjected to vigorous deproteinization procedures. After treatment with proteinase K followed by phenol extraction of samples containing D. discoideum RNase P activity, a new enzymatic activity was recovered. The proteinase K/phenol/SDS treated enzyme cleaves Schizossacharomyces pombe tRNAser (supS1), D. discoideum tRNASer and tRNALeu precursors several nucleotides upstream of the cleavage site of RNase P, liberating products with 5'-hydroxyl ends. This activity seems to be associated with one or two RNA molecules copurifying with D. discoideum RNase P activity as judged by its inhibition in the presence of micrococcal nuclease, which is in contrast to its resistance to proteinase K/phenol/SDS treatment.
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PMID:Extensive deproteinization of Dictyostelium discoideum RNase P reveals a new catalytic activity. 1127 37

The eukaryote, Dictyostelium discoideum, has one of the most (A+T) rich genomes studied to date. Isolated nuclear D. discoideum DNA (AX3 strain) was used to qualitatively determine the frequency and length distribution of long (dA).(dT) homopolymer tracts in this genome, in comparison to the less (A+T) rich calf thymus and Schistosoma mansoni DNAs that had few observable long tracts. These experimental data accurately reflect the significantly elevated frequencies of long tracts found computationally within the D. discoideum intron and flanking sequences, but not exons. PCR amplification of long (dA).(dT) homopolymer tract containing sequences was carried out. Then experimental biotinylated (dT)18 probe hybridization to the PCR amplified DNA showed that the long (dA).(dT) homopolymer tracts were enriched in D. discoideum sequences only hundreds of base pair in length, under conditions where no equivalent hybridization was observed to S. mansoni DNA or calf DNA sequences. Similar probe hybridization to DNA isolated following micrococcal nuclease digestion of D. discoideum chromatin demonstrated that long (dA).(dT) homopolymer tracts were more highly enriched in nucleosomal DNA lengths that included the internucleosomal linker as compared to shorter linker free mononucleosomal lengths. This observation is in agreement with the frequency of tract spacing results calculated from GenBank sequence data. These frequency data indicate that adjacent long tracts plus the intervening spacer DNA are found at peak lengths (average 42 bp), exactly characteristic of the internucleosomal spacer region of D. discoideum chromatin and are in sufficient number to be found in nearly half of all nucleosomes. Compared to shuffled tract sequence controls, these lengths of adjacent long tracts plus the intervening spacer DNA were found to be significantly enriched. Lesser enrichments are observed at lengths corresponding to adjacent tracts being separated by nucleosomal core length DNA sequences (145-185 bp). These data strongly suggest that adjacent long tracts occur spaced at selected lengths so as to avoid the central core regions of nucleosomes and instead are found localized within internucleosomal DNA linker and core edge regions in D. discoideum chromatin.
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PMID:Evidence for long poly(dA).poly(dT) tracts in D. discoideum DNA at high frequencies and their preferential avoidance of nucleosomal DNA core regions. 1636 78


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