A Molecular Dynamics Investigation of Compressed Aqueous Alkanoate Monolayers

Molecular dynamics are conducted on a dodecanoic acid monolayer/aqueous surface. Surface pressure is controlled by imposing constant-volume conditions for series of lengths of the square slab constituting the MD cell. The response of the alkanoate chains to the pressure is followed by examining various computed quantities that monitor their conformational order. These include atom-pair radial distribution functions, chain torsional angles, energies, atomic densities perpendicular to the interface, diffusivities and atomic plots. These quantities lead to chain separations which in the range 4-5 Å implying order when the alkanoate chains have a mean area of 0.18 nm 2.     

Two‐dimensional reference map for the basic proteome of the human dorsolateral prefrontal cortex (dlPFC) of the prefrontal lobe region of the brain

We describe a 2‐DE proteomic reference map containing 227 basic proteins in the dorsolateral prefrontal cortex region of the human brain. Proteins were separated in the first dimension on pH 6–11 IPG strips using paper‐bridge loading and on 12% SDS‐PAGE in the second dimension. Proteins were subsequently identified by MS and spectra were analyzed using an in‐house proteomics data analysis platform, Proline. The 2‐DE reference map is available via the UCD 2‐DE Proteome Database ( http://proteomics‐portal.ucd.ie:8082 ) and can also be accessed via the WORLD‐2DPAGE Portal ( http://www.expasy.ch/world‐2dpage/ ). The associated protein identification data have been submitted to the PRIDE database (accession numbers 10018–10033). Separation of proteins in the basic region resolves more membrane associated proteins relevant to the synaptic pathology central to many neurological disorders. The 2‐DE reference map will aid with further characterisation of neurological disorders such as bipolar and schizophrenia.     

Specific ion effects on macromolecular interactions in Escherichia coli extracts

Protein characterization in situ remains a major challenge for protein science. Here, the interactions of ΔTat‐GB1 in Escherichia coli cell extracts were investigated by NMR spectroscopy and size exclusion chromatography (SEC). ΔTat‐GB1 was found to participate in high molecular weight complexes that remain intact at physiologically‐relevant ionic strength. This observation helps to explain why ΔTat‐GB1 was not detected by in‐cell NMR spectroscopy. Extracts pre‐treated with RNase A had a different SEC elution profile indicating that ΔTat‐GB1 predominantly interacted with RNA. The roles of biological and laboratory ions in mediating macromolecular interactions were studied. Interestingly, the interactions of ΔTat‐GB1 could be disrupted by biologically‐relevant multivalent ions. The most effective shielding of interactions occurred in Mg²⁺‐containing buffers. Moreover, a combination of RNA digestion and Mg²⁺ greatly enhanced the NMR detection of ΔTat‐GB1 in cell extracts.     

Evolutionary history of the OmpR/IIIA family of signal transduction two component systems in Lactobacillaceae and Leuconostocaceae

Background  

Two component systems (TCS) are signal transduction pathways which typically consist of a sensor histidine kinase (HK) and a response regulator (RR). In this study, we have analyzed the evolution of TCS of the OmpR/IIIA family in Lactobacillaceae and Leuconostocaceae, two families belonging to the group of lactic acid bacteria (LAB). LAB colonize nutrient-rich environments such as foodstuffs, plant materials and the gastrointestinal tract of animals thus driving the study of this group of both basic and applied interest.     

TIM-3: a novel regulatory molecule of alloimmune activation

T cell Ig domain and mucin domain (TIM)-3 has previously been established as a central regulator of Th1 responses and immune tolerance. In this study, we examined its functions in allograft rejection in a murine model of vascularized cardiac transplantation. TIM-3 was constitutively expressed on dendritic cells and natural regulatory T cells (Tregs) but only detected on CD4(+)FoxP3(-) and CD8(+) T cells in acutely rejecting graft recipients. A blocking anti-TIM-3 mAb accelerated allograft rejection only in the presence of host CD4(+) T cells. Accelerated rejection was accompanied by increased frequencies of alloreactive IFN-γ-, IL-6-, and IL-17-producing splenocytes, enhanced CD8(+) cytotoxicity against alloantigen, increased alloantibody production, and a decline in peripheral and intragraft Treg/effector T cell ratio. Enhanced IL-6 production by CD4(+) T cells after TIM-3 blockade plays a central role in acceleration of rejection. Using an established alloreactivity TCR transgenic model, blockade of TIM-3 increased allospecific effector T cells, enhanced Th1 and Th17 polarization, and resulted in a decreased frequency of overall number of allospecific Tregs. The latter is due to inhibition in induction of adaptive Tregs rather than prevention of expansion of allospecific natural Tregs. In vitro, targeting TIM-3 did not inhibit nTreg-mediated suppression of Th1 alloreactive cells but increased IL-17 production by effector T cells. In summary, TIM-3 is a key regulatory molecule of alloimmunity through its ability to broadly modulate CD4(+) T cell differentiation, thus recalibrating the effector and regulatory arms of the alloimmune response.     

Phosphorylation of cysteine string protein on Serine 10 triggers 14-3-3 protein binding

Cysteine string protein (CSP) is a neuronal chaperone that maintains normal neurotransmitter exocytosis and is essential for preventing presynaptic neurodegeneration. CSP is phosphorylated in vivo on a single residue, Ser10, and this phosphorylation regulates its cellular functions, although the molecular mechanisms involved are unclear. To identify novel phosphorylation-specific binding partners for CSP, we used a pull-down approach using synthetic peptides and recombinant proteins. A single protein band was observed to bind specifically to a Ser10-phosphorylated CSP peptide (residues 4-14) compared to a non-phosphorylated peptide. This band was identified as 14-3-3 protein of various isoforms using mass spectrometry and Western blotting. PKA phosphorylation of full-length CSP protein stimulated 14-3-3 binding, and this was abolished in a Ser10-Ala mutant CSP, confirming the binding site as phospho-Ser10. As both CSP and 14-3-3 proteins are implicated in neurotransmitter exocytosis and neurodegeneration, this novel phosphorylation-dependent interaction may help maintain the functional integrity of the synapse.