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 C-terminal domain (CTD) of RNA polymerase II (RNAP) has an essential function in the regulation of transcription. The CTD of the human malaria parasite, Plasmodium falciparum, differs dramatically from that of higher eukaryotes. To determine whether this is a general feature of malarial parasites, we have analysed the CTD of the distantly related rodent malaria parasite P.berghei. The CTDs of the two parasites enzymes are very similar in amino acid composition and contain the basic structure of most eukaryotic CTDs, which is a tandem repeat of a heptapeptide (SPTSPSY). The CTD of P.berghei differs, however, in three aspects from the CTD of P.falciparum and other eukaryotes. First, both domains show a divergence from the consensus sequence at position 6 of the heptapeptide repeat. The Ser6 is always substituted, with a bias for lysine. The latter substitution might increase the binding efficiency to the DNA template. Second, the rodent and human malarial CTDs contain a 3' extension of, respectively, 66 or 67 amino acid residues. This tail-piece is unique among eukaryotes. Third, the enlargement of the CTD of the human parasite by six heptapeptide repeats is most likely generated by a recent amplification of a specific repeat unit.
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PMID:The C-terminal domain of RNA polymerase II of the malaria parasite Plasmodium berghei. 184 Apr 89

Nucleotide sequences in the GenEMBL database were analyzed using strategies designed to reveal species-specific patterns of DNA bending and DNA sequence. The results uncovered striking species-dependent patterns of bending with more variations among individual organisms than between prokaryotes and eukaryotes. The frequency of bent sites in sequences from different bacteria was related to genomic A + T content and this relationship was confirmed by electrophoretic analysis of genomic DNA. However, base composition was not an accurate predictor for DNA bending in eukaryotes. Sequences from C. elegans exhibited the highest frequency of bent sites in the database and the RNA polymerase II locus from the nematode was the most bent gene in GenEMBL. Bent DNA extended throughout most introns and gene flanking segments from C.elegans while exon regions lacked A-tract bending characteristics. Independent evidence for the strong bending character of this genome was provided by electrophoretic studies which revealed that a large number of the fragments from C.elegans DNA exhibited anomalous gel mobilities when compared to genomic fragments from over 20 other organisms. The prevalence of bent sites in this genome enabled us to detect selectively C.elegans sequences in a computer search of the database using as probes C.elegans introns, bending elements, and a 20 nucleotide consensus sequence for bent DNA. This approach was also used to provide additional examples of species-specific sequence patterns in eukaryotes where it was shown that (A) greater than or equal to 10 and (A.T) greater than or equal to 5 tracts are prevalent throughout the untranslated DNA of D.discodium and P.falciparum, respectively. These results provide new insight into the organization of eukaryotic DNA because they show that species-specific patterns of simple sequences are found in introns and in other untranslated regions of the genome.
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PMID:Species-specific patterns of DNA bending and sequence. 192 8

Malaria in eastern Sudan is characterised by limited seasonal transmission, with the majority of the year remaining transmission-free. Some inhabitants who contract malaria during the transmission season retain long-lasting sub-patent infections, which probably initiate transmission the following year. Here we have monitored Plasmodium falciparum infection prevalence and gametocyte production during the dry season, and examined the impact of parasite genetic multiplicity on infection longevity. A cohort of 38 individuals who were infected with P. falciparum in November 2001 was monitored monthly by microscopy and PCR until December 2002. Reverse transcriptase polymerase chain reaction of the pfg377 gene was used to detect sub-patent gametocytes. In addition, all isolates were examined for msp-2 alleles and the mean number of parasite clones per infection was estimated. We found that a large proportion (40%) of the cohort retained gametocytes throughout the dry season. The majority of patients retained asexual infection for at least 7 months. Genetic multiplicity of P. falciparum significantly influenced longevity of asexual infection and its gametocyte production. Gametocytes from mixed genotype P. falciparum infections persisted three times longer than those from single genotype infections, suggesting that genetic diversity promotes persistence. These findings are discussed in the context of the parasite biology and malaria epidemiology in the study area.
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PMID:Impact of genetic complexity on longevity and gametocytogenesis of Plasmodium falciparum during the dry and transmission-free season of eastern Sudan. 1561 15