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)

The transcription start point (tsp) of a ribosomal RNA (rRNA)-encoding gene (rDNA) from Echinococcus granulosus has been mapped at a position located 1.1 kb upstream from the small subunit (SSU) rRNA coding sequence. As expected from the analysis of the putative promoter sequence (-200 to +50), no homology was found with rDNA promoters from other organisms. Nevertheless, some interesting motifs were found. There is a d(T)11 track flanked by an inverted repeat (IR) centered at position -32, which is analogous to the position of the TATA box in promoters transcribed by RNA polymerase II. Two other IR were observed that are also present in the Trypanosoma cruzi rDNA promoter. We have also determined the SSU rDNA sequence and established a secondary structure model. The analysis of the secondary structure strongly suggests that this gene encodes a functional SSU rRNA. The fact that both the promoter and the rRNA coding sequence are derived from the same rDNA repeat indicates that the promoter is also functional.
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PMID:Characterization of a flatworm ribosomal RNA-encoding gene: promoter sequence and small subunit rRNA secondary structure. 866 75

The family Taeniidae of tapeworms is composed of two genera, Echinococcus and Taenia, which obligately parasitize mammals including humans. Inferring phylogeny via molecular markers is the only way to trace back their evolutionary histories. However, molecular dating approaches are lacking so far. Here we established new markers from nuclear protein-coding genes for RNA polymerase II second largest subunit (rpb2), phosphoenolpyruvate carboxykinase (pepck) and DNA polymerase delta (pold). Bayesian inference and maximum likelihood analyses of the concatenated gene sequences allowed us to reconstruct phylogenetic trees for taeniid parasites. The tree topologies clearly demonstrated that Taenia is paraphyletic and that the clade of Echinococcus oligarthrus and Echinococcusvogeli is sister to all other members of Echinococcus. Both species are endemic in Central and South America, and their definitive hosts originated from carnivores that immigrated from North America after the formation of the Panamanian land bridge about 3 million years ago (Ma). A time-calibrated phylogeny was estimated by a Bayesian relaxed-clock method based on the assumption that the most recent common ancestor of E. oligarthrus and E. vogeli existed during the late Pliocene (3.0 Ma). The results suggest that a clade of Taenia including human-pathogenic species diversified primarily in the late Miocene (11.2 Ma), whereas Echinococcus started to diversify later, in the end of the Miocene (5.8 Ma). Close genetic relationships among the members of Echinococcus imply that the genus is a young group in which speciation and global radiation occurred rapidly.
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PMID:Phylogenetic relationships within Echinococcus and Taenia tapeworms (Cestoda: Taeniidae): an inference from nuclear protein-coding genes. 2190 95