Alternative splicing produces structural and functional changes in CUGBP2

<p>Abstract</p> <p>Background</p> <p>CELF/Bruno-like proteins play multiple roles, including the regulation of alternative splicing and translation. These RNA-binding proteins contain two RNA recognition motif (RRM) domains at the N-terminus and another RRM at the C-terminus. CUGBP2 is a member of this family of proteins that possesses several alternatively spliced exons.</p> <p>Results</p> <p>The present study investigated the expression of exon 14, which is an alternatively spliced exon and encodes the first half of the third RRM of CUGBP2. The ratio of exon 14 skipping product (<it>R3δ</it>) to its inclusion was reduced in neuronal cells induced from P19 cells and in the brain. Although full length CUGBP2 and the CUGBP2 <it>R3δ </it>isoforms showed a similar effect on the inclusion of the smooth muscle (SM) exon of the <it>ACTN1 </it>gene, these isoforms showed an opposite effect on the skipping of exon 11 in the <it>insulin receptor </it>gene. In addition, examination of structural changes in these isoforms by molecular dynamics simulation and NMR spectrometry suggested that the third RRM of R3δ isoform was flexible and did not form an RRM structure.</p> <p>Conclusion</p> <p>Our results suggest that CUGBP2 regulates the splicing of <it>ACTN1 </it>and <it>insulin receptor </it>by different mechanisms. Alternative splicing of <it>CUGBP2 </it>exon 14 contributes to the regulation of the splicing of the <it>insulin receptor</it>. The present findings specifically show how alternative splicing events that result in three-dimensional structural changes in CUGBP2 can lead to changes in its biological activity.</p

Synthesis of well-defined hyperbranched polymers bio-based on multifunctional phenolic acids and their structure-thermal property relationships

A number of multifunctional ABx-type monomers exist in plant metabolites, and studies on the formation of hyperbranching polymers from ABx-type monomers are very significant in the development of bio-related polymeric materials. We established a method for the preparation of well-definedstructures in bio-based, hyperbranched (HB) polyarylates by the copolycondensation of caffeic acid (DHCA) as an AB_2-monomer and p-coumaric acid (4HCA) as an AB-monomer, using the highly efficient catalyst Na_2HPO_4 to regulate the polymerization speed. ^1H NMR analysis revealed the time course of the formation of the hyperbranching structures. which strongly affected the glass transition and degradation temperatures, as well as the molecular weight and composition

Performance Evaluation of Parallel Processing Environment for Molecular Dynamics

Molecular dynamics (MD) is one of the popular applications in the research field of high performance computing. Since it requires large amount of CPU time basically proportional to the square of the number of atoms simulated, acceleration of MD is essential to simulation of large biomolecules like proteins. Therefore, parallelization of MD has been actively studied long time. However, most of the studies of parallel MD report modified or newly developed algorithms specialized to some computer architectures like vector-parallel supercomputer, and an end-user of MD software cannot implement them to popular MD software developed by other ones. In this study, we evaluated performance of four kinds of computer architectures: 1) vector-parallel supercomputer, 2) multi-processor machine with shared memory, 3) multi-processor machine with distributed memory, and 4) PC cluster. Various compiler options for parallelization and optimization were tested. Experimental results revealed that if MD software is not parallelized nor vectorized in source level, use of normal PC cluster with maximum use of optimization options in compilation is the best way

Tautomerism of Histidine 64 Associated with Proton Transfer in Catalysis of Carbonic Anhydrase

The imidazole ^N signals of histidine 64 (His^), involved in the catalytic function of human carbonic anhydrase II (hCAII), were assigned unambiguously. This was accomplished by incorporating the labeled histidine as probes for solution NMR analysis, with ^N at ring-N and N^, ^C at ring-C∈1, ^C and ^N at all carbon and nitrogen, or ^N at the amide nitrogen and the labeled glycine with ^C at the carbonyl carbon. Using the pH dependence of ring-^N signals and a comparison between experimental and simulated curves, we determined that the tautomeric equilibrium constant (K_T) of His^ is 1.0, which differs from that of other histidine residues. This unique value characterizes the imidazole nitrogen atoms of His^ as both a general acid (a) and base (b): its ∈2-nitrogen as (a) releases one proton into the bulk, whereas itsδ1-nitrogen as (b) extracts another proton from a water molecule within the water bridge coupling to the zinc-bound water inside the cave. This accelerates the generation of zinc-bound hydroxide to react with the carbon dioxide. Releasing the productive bicarbonate ion from the inside separates the water bridge pathway, in which the next water molecules move into beside zinc ion. A new water molecule is supplied from the bulk to near the δ1-nitrogen of His^. These reconstitute the water bridge. Based on these features, we suggest here a catalytic mechanism for hCAII: the tautomerization of His^ can mediate the transfers of both protons and water molecules at a neutral pH with high efficiency, requiring no time- or energy-consuming processes

Phosphorylation-Induced Conformational Switching of CPI-17 Produces a Potent Myosin Phosphatase Inhibitor

Phosphorylation of endogenous inhibitor proteins for type-1 Ser/Thr phosphatase (PP1) provides a mechanism for reciprocal coordination of kinase and phosphatase activities. A myosin phosphatase inhibitor protein CPI-17 at Thr38 is phosphorylated through G-protein-mediated signals, resulting in a >1000-fold increase in inhibitory potency. We show here the solution NMR structure of phospho-T38-CPI-17 with r.m.s.d of 0.36±0.06 A for the backbone secondary structure, which reveals how phosphorylation triggers a conformational change and exposes an inhibitory surface. This active conformation is stabilized by the formation of a hydrophobic core of intercalated side chains, which is not formed in a phospho-mimetic D38 form of CPI-17. Thus, the profound increase in potency of CPI-17 arises from phosphorylation, conformational change, and hydrophobic stabilization of a rigid structure that poses the phosphorylated residue on the protein surface and restricts its hydrolysis by myosin phosphatase. Our results provide structural insights into transduction of kinase signals by PP1 inhibitor proteins