Herrmannová, K* Dotaz Zobrazit nápovědu
GLOBÁLNÍ PROBLÉMY EKOLOGICKÝCH A EKONOMICKÝCH -- SOUVISLOSTÍ • • • •. . 30 -- 2.1 Kyselá depozice a sloučeniny 2.2 Uhlovodíky a oxidy dusíku při vytváření fotochemických oxidantů . 39 -- 2.3 Oxid uhličitý a klimatické ZNEČIŠŤOVÁNÍ OVZDUŠÍ NETRADIČNÍMI ŠKODLIVINAMI . . 48 -- 3.1 Toxické kovy . 50 -- 3*2 Toxická vlákna
SIVO ; 2145
65 s. : il.
- Klíčová slova
- prostředí životní, ovzduší,
bez vyd. 56 s.
Nucleic acid sequence complementarity underlies many fundamental biological processes. Although first noticed a long time ago, sequence complementarity between mRNAs and ribosomal RNAs still lacks a meaningful biological interpretation. Here we used statistical analysis of large-scale sequence data sets and high-throughput computing to explore complementarity between 18S and 28S rRNAs and mRNA 3' UTR sequences. By the analysis of 27,646 full-length 3' UTR sequences from 14 species covering both protozoans and metazoans, we show that the computed 18S rRNA complementarity creates an evolutionarily conserved localization pattern centered around the ribosomal mRNA entry channel, suggesting its biological relevance and functionality. Based on this specific pattern and earlier data showing that post-termination 80S ribosomes are not stably anchored at the stop codon and can migrate in both directions to codons that are cognate to the P-site deacylated tRNA, we propose that the 18S rRNA-mRNA complementarity selectively stabilizes post-termination ribosomal complexes to facilitate ribosome recycling. We thus demonstrate that the complementarity between 18S rRNA and 3' UTRs has a non-random nature and very likely carries information with a regulatory potential for translational control.
- MeSH
- 3' nepřekládaná oblast * MeSH
- kodon MeSH
- proteosyntéza fyziologie MeSH
- RNA ribozomální chemie fyziologie MeSH
- terminátorové oblasti (genetika) * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- MeSH
- metabolismus MeSH
- soudní lékařství MeSH
- věkové faktory MeSH
- Publikační typ
- abstrakt z konference MeSH
In eukaryotes, for a protein to be synthesized, the 40 S subunit has to first scan the 5'-UTR of the mRNA until it has encountered the AUG start codon. Several initiation factors that ensure high fidelity of AUG recognition were identified previously, including eIF1A, eIF1, eIF2, and eIF5. In addition, eIF3 was proposed to coordinate their functions in this process as well as to promote their initial binding to 40 S subunits. Here we subjected several previously identified segments of the N-terminal domain (NTD) of the eIF3c/Nip1 subunit, which mediates eIF3 binding to eIF1 and eIF5, to semirandom mutagenesis to investigate the molecular mechanism of eIF3 involvement in these reactions. Three major classes of mutant substitutions or internal deletions were isolated that affect either the assembly of preinitiation complexes (PICs), scanning for AUG, or both. We show that eIF5 binds to the extreme c/Nip1-NTD (residues 1-45) and that impairing this interaction predominantly affects the PIC formation. eIF1 interacts with the region (60-137) that immediately follows, and altering this contact deregulates AUG recognition. Together, our data indicate that binding of eIF1 to the c/Nip1-NTD is equally important for its initial recruitment to PICs and for its proper functioning in selecting the translational start site.
- MeSH
- eukaryotický iniciační faktor 3 genetika metabolismus MeSH
- iniciace translace peptidového řetězce fyziologie MeSH
- kodon iniciační genetika metabolismus MeSH
- malé podjednotky ribozomu eukaryotické genetika metabolismus MeSH
- multiproteinové komplexy genetika metabolismus MeSH
- Saccharomyces cerevisiae - proteiny genetika metabolismus MeSH
- Saccharomyces cerevisiae genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The 12-subunit mammalian eIF3 is the largest and most complex translation initiation factor and has been implicated in numerous steps of translation initiation, termination and ribosomal recycling. Imbalanced eIF3 expression levels are observed in various types of cancer and developmental disorders, but the consequences of altered eIF3 subunit expression on its overall structure and composition, and on translation in general, remain unclear. We present the first complete in vivo study monitoring the effects of RNAi knockdown of each subunit of human eIF3 on its function, subunit balance and integrity. We show that the eIF3b and octameric eIF3a subunits serve as the nucleation core around which other subunits assemble in an ordered way into two interconnected modules: the yeast-like core and the octamer, respectively. In the absence of eIF3b neither module forms in vivo, whereas eIF3d knock-down results in severe proliferation defects with no impact on eIF3 integrity. Disrupting the octamer produces an array of subcomplexes with potential roles in translational regulation. This study, outlining the mechanism of eIF3 assembly and illustrating how imbalanced expression of eIF3 subunits impacts the factor's overall expression profile, thus provides a comprehensive guide to the human eIF3 complex and to the relationship between eIF3 misregulation and cancer.
