1,721,145 research outputs found
The N-terminal domain of 2',3'-cyclic nucleotide 3'-phosphodiesterase harbors a GTP/ATP binding site
No full textThe interaction between 2',3'-cyclic nucleotide 3'-phosphodiesterase and guanine/adenine nucleotides was investigated. The binding of purine nucleotides to 2',3'-cyclic nucleotide 3'-phosphodiesterase was revealed by both direct and indirect methods. In fact, surface plasmon resonance experiments, triphosphatase activity measurements, and fluorescence experiments revealed that 2',3'-cyclic nucleotide 3'-phosphodiesterase binds purine nucleotide triphosphates with an affinity higher than that displayed for diphosphates; on the contrary, the affinity for both purine monophosphates and pyrimidine nucleotides was negligible. An interpretation of biological experimental data was achieved by a building of 2',3'-cyclic nucleotide 3'-phosphodiesterase N-terminal molecular model. The structural elements responsible for nucleotide binding were identified and potential complexes between the N-terminal domain of CNP-ase and nucleotide were analyzed by docking simulations. Therefore, our findings suggest new functional and structural property of the N-terminal domain of CNPase
Espressione della metalloproteinasi-9 ed effetto di estratti polifenolici su cellule MKN28
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Archaeal elongation factor 1a from Sulfolobus solfataricus interacts with the eubacterial antibiotic GE2270A
No full textThe thiazolyl-peptide antibiotic GE2270A, an inhibitor of the elongation factor Tu from Escherichia coli (EcEF-Tu), was used to study the effects produced in the biochemical properties of the archaeal functional analogue elongation factor 1a from Sulfolobus solfa- taricus (SsEF-1a). GE2270A did not substantially affect the poly(U)-directed-poly(Phe) incorporation catalyzed by SsEF-1a and the formation of the ternary complex SsEF-1aÆGTPÆPhe-tRNAPhe. On the other hand, the antibiotic was able to increase the GDP/GTP exchange rate of SsEF-1a; nevertheless, this improvement was not associated with an increase in the catalytic activity of the enzyme. In fact, GE2270A inhibited both the intrinsic GTPase of SsEF-1a (GTPaseNa) and that stimulated by ribosomes. Interestingly, GTPaseNa of both intact and C-terminal-deleted SsEF-1a resulted in a greater sensi- tivity to the antibiotic with respect to SsEF-1a lacking both the M- and C-terminal domains. This result sug- gested that, similar to what is found for EcEF-Tu, the M domain of SsEF-1a is the region of the enzyme most responsible for the interaction with GE2270A. The dif- ferent behavior observed in the inhibition of protein synthesis with respect to EcEF-Tu can be ascribed to the different adaptive structural changes that have occurred in SsEF-1a during evolution
The interaction between the archaeal elongation factor 1alpha and its nucleotide exchange factor 1beta
No full textIn Sulfolobus solfataricus the binding of the exchange factor 1b (SsEF-1b) to SsEF-1aGDP displaces the nucleotide and the SsEF-1aSsEF-1b complex is formed. The complex itself is stable, but it dissociates upon the addition of GDP or Gpp(NH)p but not ATP. Since the rate of the formation of the SsEF-1aSsEF-1b complex is significatively slower than the rate of the nucleotide exchange catalyzed by SsEF-1b it can be inferred that in vivo the GDP/GTP exchange reaction proceeds via an SsEF-1aSsEF-1b interaction without involving the formation of a stable binary complex as an intermediate
Resistance of archaebacterial aEF-1A/GDP against denaturation by heat and urea
No full textThe elongation factor aEF-1 alpha, isolated as aEF-1 alpha.GDP from the thermoacidophilic archaebacterium Sulfolobus solfataricus, exchanges GDP for [3H]GDP at a rate which reaches a maximum at 95 degrees C. The rate constants at different temperatures of the heat inactivation of aEF-1 alpha.GDP are considerably lower compared to those referred to Escherichia coli EF-Tu.GDP. The Tm values determined for both aEF-1 alpha.GDP and EF-Tu.GDP are 97 and 53 degrees C, respectively. The addition of GDP during the heat treatment protects significantly EF-Tu.GDP but only slightly aEF-1 alpha.GDP. The ability of aEF-1 alpha.GDP to exchange GDP for [3H]GDP is impaired at 70 degrees C by urea at concentrations which are greater compared to those required to inactivate E. coli EF-Tu.GDP at 45 degrees C; apparently both factors are not protected by GDP against inactivation by urea
PHYSICAL ACTIVITY AND COGNITIVE FUNCTIONS: ROLE OF THE BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF)
Full text linkThe skeletal muscle is considered an endocrine organ as it secretes various myokines. The myokines are produced during skeletal muscle contraction and exert autocrine, paracrine, and endocrine effects even on different organs and tissues. Up to now, many myokines have been described, including the brain-derived neurotrophic factor (BDNF), interleukin-6 (IL-6), irisin, leukemia inhibitory factor (LIF), and insulin-like growth factor1 (IGF-1) are the most relevant also for brain functions. In particular, it is well known that BDNF ameliorates cognitive functions via neuronal differentiation and plasticity in the hippocampal region. Therefore, myokines represent key molecules in the cross-talk between skeletal muscle and brain
Studies on the polypeptide elongation factor 2 from Sulfolobus solfataricus
No full textThe elongation factor 2 from the thermoacidophilic archaeon Sulfolobus solfataricus (SsEF-2) binds [3H]GDP at 1:1 molar ratio. The bound [3H]GDP is displaced by GTP or its nonhydrolyzable analogue guanyl-5'-yl imidodiphosphate (Gpp(NH)p) but not by ATP, thus indicating that only the two guanosine nucleotides compete for the same binding site. The affinity of SsEF-2 for [3H]GDP is higher than that for GTP and Gpp(NH)p. On the contrary, in the presence of ribosomes the affinity of SsEF-2 for GDP is lower than that for Gpp(NH)p. SsEF-2 is endowed with an intrinsic hardly detectable GTPase activity that is stimulated by ribosomes up to 2000-fold. The ribosome-stimulated SsEF-2 GTPase (GTPaser) reaches a maximum at pH 7.8 and is not affected by ATP but is competitively inhibited by either GDP or Gpp(NH)p. Both Km for [gamma-32P]GTP and kcat of GTPaser increase with increasing temperature, and the highest catalytic efficiency is reached at 80 degrees C. The ADP-ribosylation of SsEF-2 does not significantly affect either the binding of GDP and GTP or the kinetics of the GTPaser. A hypothesis on the stimulation by ribosome of SsEF-2 GTPase is proposed
Archaeal elongation factor 1 alpha from Sulfolobus solfataricus interacts with the eubacterial antibiotic GE2270A
No full textThe thiazolyl-peptide antibiotic GE2270A, an inhibitor of the elongation factor Tu from Escherichia coli (EcEF-Tu), was used to study the effects produced in the biochemical properties of the archaeal functional analogue elongation factor 1alpha from Sulfolobus solfataricus (SsEF-1alpha). GE2270A did not substantially affect the poly(U)-directed-polyPhe incorporation catalyzed by SsEF-1alpha and the formation of the ternary complex SsEF-1alpha.GTP.Phe-tRNAPhe. On the other hand, the antibiotic was able to increase the GDP/GTP exchange rate of SsEF-1alpha; nevertheless, this improvement was not associated with an increase in the catalytic activity of the enzyme. In fact, GE2270A inhibited both the intrinsic GTPase of SsEF-1alpha (GTPaseNa) and that stimulated by ribosomes. Interestingly, GTPaseNa of both intact and C-terminal-deleted SsEF-1alpha resulted in a greater sensitivity to the antibiotic with respect to SsEF-1alpha lacking both the M- and C-terminal domains. This result suggested that, similar to what is found for EcEF-Tu, the M domain of SsEF-1alpha is the region of the enzyme most responsible for the interaction with GE2270A. The different behavior observed in the inhibition of protein synthesis with respect to EcEF-Tu can be ascribed to the different adaptive structural changes that have occurred in SsEF-1alpha during evolution
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