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Molecular paleontology: a biochemical model of the ancestral ribosome.

ABSTRACT: Ancient components of the ribosome, inferred from a consensus of previous work, were constructed in silico, in vitro and in vivo. The resulting model of the ancestral ribosome presented here incorporates ?20% of the extant 23S rRNA and fragments of five ribosomal proteins. We test hypotheses that ancestral rRNA can: (i) assume canonical 23S rRNA-like secondary structure, (ii) assume canonical tertiary structure and (iii) form native complexes with ribosomal protein fragments. Footprinting experiments support formation of predicted secondary and tertiary structure. Gel shift, spectroscopic and yeast three-hybrid assays show specific interactions between ancestral rRNA and ribosomal protein fragments, independent of other, more recent, components of the ribosome. This robustness suggests that the catalytic core of the ribosome is an ancient construct that has survived billions of years of evolution without major changes in structure. Collectively, the data here support a model in which ancestors of the large and small subunits originated and evolved independently of each other, with autonomous functionalities.

SUBMITTER: Hsiao C

PROVIDER: S-EPMC3597689 | biostudies-literature | 2013 Mar

REPOSITORIES: biostudies-literature

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Molecular paleontology: a biochemical model of the ancestral ribosome.

Hsiao Chiaolong C Lenz Timothy K TK Peters Jessica K JK Fang Po-Yu PY Schneider Dana M DM Anderson Eric J EJ Preeprem Thanawadee T Bowman Jessica C JC O'Neill Eric B EB Lie Lively L Athavale Shreyas S SS Gossett J Jared JJ Trippe Catherine C Murray Jason J Petrov Anton S AS Wartell Roger M RM Harvey Stephen C SC Hud Nicholas V NV Williams Loren Dean LD

Nucleic acids research 20130125 5

Ancient components of the ribosome, inferred from a consensus of previous work, were constructed in silico, in vitro and in vivo. The resulting model of the ancestral ribosome presented here incorporates ∼20% of the extant 23S rRNA and fragments of five ribosomal proteins. We test hypotheses that ancestral rRNA can: (i) assume canonical 23S rRNA-like secondary structure, (ii) assume canonical tertiary structure and (iii) form native complexes with ribosomal protein fragments. Footprinting experi ...[more]

PMID: 23355613

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Project description:The present study aimed at proposing a novel chemically-induced cirrhosis-associated rat hepatocarcinogenesis model, involving the characterization of histological, biochemical and molecular features. Male Wistar rats received a single dose of diethylnitrosamine (DEN, 200 mg/Kg body weight [b.wt.]), and were submitted to several cycles of thioacetamide (TAA, 200 mg/Kg b.wt.), during 23 weeks. Blood and liver were collected from untreated and DEN/TAA-treated groups. Liver samples were processed for global gene expression (cDNA microarray), histopathological (HE) and collagen content (picrosirius red) evaluations, immunohistochemical (Ki-67, GST-P and α-SMA), biochemical (catalase, glutathione peroxidase and glutathione-S-transferase) and gelatin zymography (MMP-2 and 9) analysis. Using a very stringent analysis (FDR<0.01 and fold change>3), gene expression array evidenced 359 differentially expressed genes upon DEN/TAA regimen. Gene Ontology and functional analyses showed several upregulated genes involved in extracellular matrix organization, mainly collagen type I α1 and 2 (Col1α1, Col1α2) and tissue inhibitor of metalloproteinase 1 and 2 (Timp1 and Timp2) genes. In addition, glutathione S-transferase, pi 1 and 2 (Gstp1 and Gstp2) genes were markedly upregulated. In contrast, functional analyses also revealed the downregulation of antioxidant response genes, as catalase, glutathione peroxidase 1 and glutathione S-transferase mu type 3 (Cat, Gpx1 and Gstm3). In agreement with gene expression data, our model presented extensive liver cirrhosis with increased α-SMA expression and collagen deposition, as well as marked development of preneoplastic GST-P positive hyperplastic lesions and some neoplasms. Besides, we observed a decrease in total glutathione peroxidase, total glutatione-S-tranferase and catalase activities. The characterization of a suitable cirrhosis-associated hepatocarcinogenesis model could provide insights into molecular characteristics of the human disease and be applied to evaluate potential preventive and therapeutic approaches.

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Molecular paleontology: a biochemical model of the ancestral ribosome.

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Molecular paleontology: a biochemical model of the ancestral ribosome.

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