Search results for "Biosynthesi"
showing 10 items of 526 documents
Contribution of polyadenylate sequences to the translational efficiency of globin messenger RNAs
1987
mRNAs from reticulocyte polysomes were fractionated by chromatography on poly(U)-Sepharose and thermal elution. The molar ratio of alpha- to beta-globin mRNA was found to be 2:1 and 1:1 respectively in short- and long-poly(A) size classes. Translational analyses indicated that the globin mRNAs containing long poly(A) tracts (with a mean length of about 70 nucleotides) directed protein synthesis with higher rates than did mRNA containing short poly(A) tracts (15-35 nucleotides). Experiments performed with sub-saturating mRNA concentrations showed that the digestion with RNAase H induced a decrease in the translational capacity of both globin mRNAs and an increase in the alpha- to beta-globin…
3D-Structure and function of strictosidine synthase--the key enzyme of monoterpenoid indole alkaloid biosynthesis.
2008
Strictosidine synthase (STR; EC 4.3.3.2) plays a key role in the biosynthesis of monoterpenoid indole alkaloids by catalyzing the Pictet-Spengler reaction between tryptamine and secologanin, leading exclusively to 3alpha-(S)-strictosidine. The structure of the native enzyme from the Indian medicinal plant Rauvolfia serpentina represents the first example of a six-bladed four-stranded beta-propeller fold from the plant kingdom. Moreover, the architecture of the enzyme-substrate and enzyme-product complexes reveals deep insight into the active centre and mechanism of the synthase highlighting the importance of Glu309 as the catalytic residue. The present review describes the 3D-structure and …
Improved Expression of His6-Tagged Strictosidine Synthase cDNA for Chemo-Enzymatic Alkaloid Diversification
2010
Strictosidine synthase (STR1) catalyzes the stereoselective formation of 3alpha(S)-strictosidine from tryptamine and secologanin. Strictosidine is the key intermediate in the biosynthesis of 2,000 plant monoterpenoid indole alkaloids, and it is a key precursor of enzyme-mediated synthesis of alkaloids. An improved expression system is described which leads to optimized His(6)-STR1 synthesis in Escherichia coli. Optimal production of STR1 was achieved by determining the impact of co-expression of chaperones pG-Tf2 and pG-LJE8. The amount and activity of STR1 was doubled in the presence of chaperone pG-Tf2 alone. His(6)-STR1 immobilized on Ni-NTA can be used for enzymatic synthesis of stricto…
Crystallization and preliminary X-ray analysis of strictosidine synthase and its complex with the substrate tryptamine
2005
Strictosidine synthase (STR1) is a central enzyme that participates in the biosynthesis of almost all plant monoterpenoid indole alkaloids. After heterologous expression in Escherichia coli, crystals of STR1 and its substrate complex with tryptamine were obtained by the hanging-drop technique at 302–304 K with potassium sodium tartrate tetrahydrate as precipitant. All crystals belong to space group R3. The native STR1 crystals diffract to 2.95 Å and have unit-cell parameters a = b = 150.3, c = 122.4 Å. The tryptamine complex crystals diffract to 2.38 Å, with unit-cell parameters a = b = 147.3, c = 122.3 Å.
Exiguobacterium pavilionensis str. N139, a halotolerant, UV-B and metal resistant bacteria from a high-altitude Andean lake
2016
We report the genome sequence of Exiguobacterium pavilionensis str. N139, isolated from a high-altitude Andean lake. The 2,952,588-bp genome contains one chromosome and three megaplasmids. The genome analysis suggests the presence of enzymes that confer E. pavilionensis str. N139 the ability to grow under multiple environmental extreme conditions, including high concentrations of different metals and high ultraviolet B radiation. Moreover, the regulation of its tryptophan biosynthesis suggests that novel pathways remain to be discovered, and that these pathways might be fundamental in the amino acid metabolism of the microbial community from Laguna Negra, Argentina .
von Hippel-Lindau Protein-Mediated Repression of Tumor Necrosis Factor Alpha Translation Revealed through Use of cDNA Arrays
2003
Based on evidence that the von Hippel-Lindau (VHL) tumor suppressor protein is associated with polysomes and interacts with translation regulatory factors, we set out to investigate the potential influence of pVHL on protein translation. To this end, renal cell carcinoma (RCC) cells that either lacked pVHL or expressed pVHL through stable transfection were used to prepare RNA from cytosolic (unbound) and polysome-bound fractions. Hybridization of cDNA arrays using RNA from each fraction revealed a subset of transcripts whose abundance in polysomes decreased when pVHL function was restored. The tumor necrosis factor alpha (TNF-alpha) mRNA was identified as one of the transcripts that prefere…
Conserved alternative splicing in the 5'-untranslated region of the muscle-specific enolase gene. Primary structure of mRNAs, expression and influenc…
1995
We report here the isolation and characterization of cDNAs covering the 5'-end region of mouse and rat mRNAs that encode the beta or muscle-specific isoform of the glycolytic enzyme enolase. As previously determined for humans, two classes of beta-enolase transcripts with distinct sequences in their 5'-untranslated regions are present in both mouse and rat muscles. A mechanism of alternative splicing, conserved from mouse to man, generates the two forms of mRNA. Secondary-structure predictions indicated that, in all cases, a more stable secondary structure could exist in the 5' end of the message with the longer leader. In vitro transcripts containing defined human or mouse 5'-untranslated …
Thymidylate synthase polymorphism and microsatellite instability: association in colorectal cancer.
2005
5-Fluorouracil (5FU) is the main drug used for the treatment of colorectal cancer (CRC) and Thymidilate Synthase (TS) is its target enzyme. TS gene has regulatory tandemly repeated sequences in its 5'' and 3''untraslated region (5''-3'' UTR). CRC often shows a kind of genomic instability called Microsatellite Instability (MSI) that is associated with TS levels and survival. Our data show that the genotype 2R/2R (homozygosity for 2 tandem repeat sequences in the 5''UTR) is more frequently associated with MSI+ and lower TS levels. More over we did not find any significant association between the 2R/3R (heterozygosity for 2 and 3 tandem repeat sequences in the 5''UTR) and 3R/3R (homozygosity f…
Regulation of mRNA transport, localization and translation in the nervous system of mammals (Review).
2014
Post-transcriptional control of mRNA trafficking and metabolism plays a critical role in the actualization and fine tuning of the genetic program of cells, both in development and in differentiated tissues. Cis-acting signals, responsible for post-transcriptional regulation, reside in the RNA message itself, usually in untranslated regions, 5' or 3' to the coding sequence, and are recognized by trans-acting factors: RNA-binding proteins (RBPs) and/or non-coding RNAs (ncRNAs). ncRNAs bind short mRNA sequences usually present in the 3'-untranslated (3'-UTR) region of their target messages. RBPs recognize specific nucleotide sequences and/or secondary/tertiary structures. Most RBPs assemble on…
3'-Untranslated regions of oxidative phosphorylation mRNAs function in vivo, as enhancers of translation
2000
Recent findings have indicated that the 3´-untranslated region (3´-UTR) of the mRNA encoding the β-catalytic subunit of the mitochondrial H+-ATP synthase has an in vitro translation-enhancing activity (TEA) [Izquierdo and Cuezva, Mol. Cell. Biol. (1997) 17, 5255–5268; Izquierdo and Cuezva, Biochem. J. (2000) 346, 849–855]. In the present work, we have expressed chimaeric plasmids that encode mRNA variants of green fluorescent protein in normal rat kidney and liver clone 9 cells to determine whether the 3´-UTRs of nuclear-encoded mRNAs involved in the biogenesis of mitochondria have an intrinsic TEA. TEA is found in the 3´-UTR of the mRNAs encoding the α- and β-subunits of the rat H+-ATP syn…