دانلود رایگان ترجمه مقاله RNA پلیمراز II و مکانیزم پایه رونویسی – NCBI 2013
دانلود رایگان مقاله انگلیسی مکانیسم پایه رونویسی توسط RNA پلیمراز II به همراه ترجمه فارسی
عنوان فارسی مقاله | مکانیسم پایه رونویسی توسط RNA پلیمراز II |
عنوان انگلیسی مقاله | Basic mechanism of transcription by RNA polymerase II |
رشته های مرتبط | زیست شناسی، ژنتیک، علوم سلولی و مولکولی |
کلمات کلیدی | RNA پلیمراز، انتقال نوکلئوتیدیل، کاتالیز دو یون فلزی، رونویسی، دینامیک مولکولی |
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نشریه | NCBI |
مجله | مجله بیوشیمی و بیوفیزیک – Biochemistry and Biophysica Acta |
سال انتشار | 2013 |
کد محصول | F859 |
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جستجوی ترجمه مقالات | جستجوی ترجمه مقالات زیست شناسی |
فهرست مقاله: چکیده |
بخشی از ترجمه فارسی مقاله: مقدمه |
بخشی از مقاله انگلیسی: Introduction Transcription of cellular genomes in all domains of life is carried out by essentially orthologous enzymes, multi-subunit DNA-dependent RNA polymerases (RNAPs). The archetypal eubacterial core enzyme, represented by that of Escherichia coli, consists of two large subunits (β and β′) 1,2, that carry out the chemical (NTP condensation) and mechanical (translocation) steps3,4, and three smaller ones, α2 dimer, and ω, that play roles in the assembly of the enzyme and regulation of transcription1,2,4,5 (Fig. 1A). Variant forms of the core are described for some Eubacteria, such as Francisella (featuring α1α2 heterodimer6 ), and Bacillus (adding δ and alternate ω subunits7 ), whereas in Helicobacter, Wolbachia and Wolinella RNAPs β and β′ subunits are fused together1 . RNAP subunit initially described as γ in Nostoc, Anabaena, and other Cyanobacteria turned out to be a product of a split in the ancestral gene, coding for β′ ortholog8,9. A similar split exists in the β′ subunit of plastid-encoded RNAPs in chloroplasts, featuring a reduced bacterial-type core α2ββ′ (ω subunit appears to be encoded by plastid genomes only in Rhodophyta algae)10 . Interestingly, this core architecture predominates in early chloroplast development (e.g. in etioplasts), whereas in mature chloroplasts it is augmented by up to 30 additional subunits11 . Mitochondrial RNAPs are predominantly related to those of bacteriophages, but the relatively large mitochondrial genomes of some protists (namely Jakobidae and Malawimonadidae) encode orthologs of bacterial α, β, and β′ subunits12,13 . Nuclear RNAPs in Eukaryota are represented by a minimal set of three classes: RNAPI transcribing ribosomal RNA genes, RNAPII carrying out the synthesis of messenger RNA and a subset of small non-coding RNAs, and RNAPIII synthesizing transfer RNAs, 5S RNA, and the bulk of small non-coding RNAs14–17. RNAPs from each class contain 12+ subunits, with a core orthologous to bacterial-type enzyme: yeast RNAPII largest subunits, Rpb1 and Rpb2, correspond to β′ and β, respectively, Rpb3 and Rpb11 are divergent orthologs of α, and Rpb6 is an ω ortholog18–20 (Fig. 1B). In plants the set of nuclear RNAPs is extended to 5, RNAPIV and V conforming to the overall architecture of RNAPI-III21–23 , but exhibiting an unexpected divergence in the mechano-chemical core24,25, otherwise universally conserved in both pro- and eukaryotes, which led some to question the competence of these enzymes to act as bona fide RNAPs24 (this competence still eludes in vitro demonstration22). Genomes of large viruses from the order Megavirales encode RNAPs, related to the nuclear RNAPII, but with a reduced complement of subunits, typically numbering 826. Remarkably, whereas some enzymes, such as that of Mimivirus, feature a fully conserved α2ββ′ω-like core, namely the orthologs of Rpb1, 2, 3/11, and 6 (together with Rpb5, 9, and 10 homologs)27, RNAPs from poxviruses lack an apparent α ortholog28,29, indicating a potentially dramatic change in enzyme architecture and assembly. Lane and Darst, based on the results of their large-scale multiple sequence alignment for β,β ′-like subunits, argued that poxvirus RNAPs were related to the nuclear RNAPI enzymes1 . Finally, Archaea contain one type of RNAPs, similar in size (11–13 subunits) and composition to RNAPII: it comprises orthologs of Rpb1 (split into two subunits), 2–8, 10, and 1230,31 (Fig. 1C). Further in depth analysis of structural and sequence data pertaining to RNAPs from bacteria, archaea, and eukaryotes is provided by Cramer, Darst, Kornberg, Murakami, Yokoyama and colleagues1,2,18–20,30–33. In this review we will focus on the basic mechanism of transcription, as it emerges from studies of yeast RNAPII, complemented when necessary with the relevant data for bacterial enzymes. |