Synthesis and structure of an intramolecularly coordinated diaryltelluronic acid and its dimethyl ester

The oxidation of the telluroxane cluster (8Me₂NC₁₀H₆Te)₆O₈(OH)₂ (4) or the diaryl ditelluride (8-Me₂NC₁₀H₆Te)(₂) (7) using H₂O₂ provided the diarylditelluronic acid [8-Me₂NC₁₀H₆Te(O)(OH)₂]₂(O) (6), which is the second member of this compound class and the first one to contain an intramolecularly coordinated substituent. Attempts at recrystallizing 6 from Methanol provided the partial ester [8-Me₂NC₁₀H₆Te(O)(OH)(OMe)]₂(O) (8). In addition structural motifs of known diaryltelluronic acids were compared using DFT calculations.

NeoGeoNative

NeoGeoNative is about my uneasy relationship with the appropriation of Indigenous motifs in contemporary fashion to which I am both attracted and repelled. Cheap 'triba' leggings that I have purchased from places like Sportsgirl, Glassons and the Preston Market have been edited into a kind of hypnotic/seductive kaleidoscope of colour and patterns - that reference the Melanesian, Polynesian and Native American designs that they appropriate - but at the same time are completely decontextualised, re-emerging as neon mandalas and other sacred geometry.

Cotranslational assembly of the yeast SET1C histone methyltransferase complex

 While probing the role of RNA for the function of SET1C/COMPASS histone methyltransferase, we identified SET1RC (SET1 mRNA-associated complex), a complex that contains SET1 mRNA and Set1, Swd1, Spp1 and Shg1, four of the eight polypeptides that constitute SET1C. Characterization of SET1RC showed that SET1 mRNA binding did not require associated Swd1, Spp1 and Shg1 proteins or RNA recognition motifs present in Set1. RNA binding was not observed when Set1 protein and SET1 mRNA were derived from independent genes or when SET1 transcripts were restricted to the nucleus. Importantly, the protein-RNA interaction was sensitive to EDTA, to the translation elongation inhibitor puromycin and to the inhibition of translation initiation in prt1-1 mutants. Taken together, our results support the idea that SET1 mRNA binding was dependent on translation and that SET1RC assembled on nascent Set1 in a cotranslational manner. Moreover, we show that cellular accumulation of Set1 is limited by the availability of certain SET1C components, such as Swd1 and Swd3, and suggest that cotranslational protein interactions may exert an effect in the protection of nascent Set1 from degradation.

Between-strand disulfides: Forbidden disulfides linking adjacent ß-Strands

Between-strand disulfides (BSDs) connect cysteine (Cys) residues across adjacent strands of β-sheets. There are four BSD types which can be found in regular β-structure: CSDs, which link residues immediately opposite each other in the β-structure (residues i and j); ETDs, which connect Cys out of register by one residue (i and j ± 1); BDDs, which join Cys at positions i and j ± 2; and BFDs, which link residues i and j ± 3. Formation of these disulfides was initially predicted to be forbidden, producing too much local strain in the protein fold. However, BSDs do exist in nature. Significantly, their high levels of strain allow them to be involved in redox processes under physiological conditions. Here we characterise BSD motifs found in the Protein Data Bank (PDB), discussing important intrinsic factors, such as the disulfide conformation and torsional strain, and extrinsic factors, such as the influence of the β-sheet environment on the disulfide and vice versa. We also discuss the biological importance of BSDs, including the prevalence of non-homologous examples in the PDB, the conservation of BSD motifs amongst related proteins (BSD clusters) and experimental evidence for BSD redox activity. For clusters of homologous BSDs we present detailed data of the disulfide properties and the variations of these properties amongst the “redundant” structures. Identification of disulfides with the potential to be involved in biological redox processes via the analysis of these data will provide important insights into the function and mechanism of BSD-containing proteins. Characterisation of thiol-based redox signalling pathways will lead to significant breakthroughs in understanding the molecular basis of oxidative stress and associated pathways, such as ageing and neurodegenerative diseases.

The spectacle of the ordinary: painting the everyday

This presentation shows paintings that further explore my interest in depicting the complexities’ of contemporary urban life - images, concepts, and motifs from our everyday experience.

Curtains and Doors: Imagery of Precipitation

This refereed conference paper discusses the symbolic unity of various visual motifs in terms of philosophy and metaphysics.  Linking themes to the visual use of curtains and doorways as ques to precipitous events.  

ADAMTS4 and ADAMTS5 knockout mice are protected from versican but not aggrecan or brevican proteolysis during spinal cord injury

The chondroitin sulfate proteoglycans (CSPGs) aggrecan, versican, and brevican are large aggregating extracellular matrix molecules that inhibit axonal growth of the mature central nervous system (CNS). ADAMTS proteoglycanases, including ADAMTS4 and ADAMTS5, degrade CSPGs, representing potential targets for ameliorating axonal growth-inhibition by CSPG accumulation after CNS injury. We investigated the proteolysis of CSPGs in mice homozygous for Adamts4 or Adamts5 null alleles after spinal cord injury (SCI). ADAMTS-derived 50-60 kDa aggrecan and 50 kDa brevican fragments were observed in Adamts4-/-, Adamts5-/-, and wt mice but not in the sham-operated group. By contrast Adamts4-/- and Adamts5-/- mice were both protected from versican proteolysis with an ADAMTS-generated 70 kDa versican fragment predominately observed in WT mice. ADAMTS1, ADAMTS9, and ADAMTS15 were detected by Western blot in Adamts4-/- mice' spinal cords after SCI. Immunohistochemistry showed astrocyte accumulation at the injury site. These data indicate that aggrecan and brevican proteolysis is compensated in Adamts4-/- or Adamts5-/- mice by ADAMTS proteoglycanase family members but a threshold of versican proteolysis is sensitive to the loss of a single ADAMTS proteoglycanase during SCI. We show robust ADAMTS activity after SCI and exemplify the requirement for collective proteolysis for effective CSPG clearance during SCI.

Mimtags: the use of phage display technology to produce novel protein-specific probes

In recent times the use of protein-specific probes in the field of proteomics has undergone evolutionary changes leading to the discovery of new probing techniques. Protein-specific probes serve two main purposes: epitope mapping and detection assays. One such technique is the use of phage display in the random selection of peptide mimotopes (mimtags) that can tag epitopes of proteins, replacing the use of monoclonal antibodies in detection systems. In this study, phage display technology was used to screen a random peptide library with a biologically active purified human interleukin-4 receptor (IL-4R) and interleukin-13 (IL-13) to identify mimtag candidates that interacted with these proteins. Once identified, the mimtags were commercially synthesised, biotinylated and used for in vitro immunoassays. We have used phage display to identify M13 phage clones that demonstrated specific binding to IL-4R and IL-13 cytokine. A consensus in binding sequences was observed and phage clones characterised had identical peptide sequence motifs. Only one was synthesised for use in further immunoassays, demonstrating significant binding to either IL-4R or IL-13. We have successfully shown the use of phage display to identify and characterise mimtags that specifically bind to their target epitope. Thus, this new method of probing proteins can be used in the future as a novel tool for immunoassay and detection technique, which is cheaper and more rapidly produced and therefore a better alternative to the use of monoclonal antibodies.

Redox sulfur chemistry of the copper chaperone Atox1 is regulated by the enzyme glutaredoxin 1, the reduction potential of the glutathione couple GSSG/2GSH and the availability of Cu(I)

Glutaredoxins have been characterised as enzymes regulating the redox status of protein thiols via cofactors GSSG/GSH. However, such a function has not been demonstrated with physiologically relevant protein substrates in in vitro experiments. Their active sites frequently feature a Cys-xx-Cys motif that is predicted not to bind metal ions. Such motifs are also present in copper-transporting proteins such as Atox1, a human cytosolic copper metallo-chaperone. In this work, we present the first demonstration that: (i) human glutaredoxin 1 (hGrx1) efficiently catalyses interchange of the dithiol and disulfide forms of the Cys(12)-xx-Cys(15) fragment in Atox1 but does not act upon the isolated single residue Cys(41); (ii) the direction of catalysis is regulated by the GSSG/2GSH ratio and the availability of Cu(I); (iii) the active site Cys(23)-xx-Cys(26) in hGrx1 can bind Cu(I) tightly with femtomolar affinity (K(D) = 10(-15.5) M) and possesses a reduction potential of E(o)' = -118 mV at pH 7.0. In contrast, the Cys(12)-xx-Cys(15) motif in Atox1 has a higher affinity for Cu(I) (K(D) = 10(-17.4) M) and a more negative potential (E(o)' = -188 mV). These differences may be attributed primarily to the very low pKa of Cys23 in hGrx1 and allow rationalisation of conclusion (ii) above: hGrx1 may catalyse the oxidation of Atox1(dithiol) by GSSG, but not the complementary reduction of the oxidised Atox1(disulfide) by GSH unless Cu(aq)(+) is present at a concentration that allows binding of Cu(I) to reduced Atox1 but not to hGrx1. In fact, in the latter case, the catalytic preferences are reversed. Both Cys residues in the active site of hGrx1 are essential for the high affinity Cu(I) binding but the single Cys(23) residue only is required for the redox catalytic function. The molecular properties of both Atox1 and hGrx1 are consistent with a correlation between copper homeostasis and redox sulfur chemistry, as suggested by recent cell experiments. These proteins appear to have evolved the features necessary to fill multiple roles in redox regulation, Cu(I) buffering and Cu(I) transport.

Mutational interference mapping experiment (MIME) for studying RNA structure and function

RNA regulates many biological processes; however, identifying functional RNA sequences and structures is complex and time-consuming. We introduce a method, mutational interference mapping experiment (MIME), to identify, at single-nucleotide resolution, the primary sequence and secondary structures of an RNA molecule that are crucial for its function. MIME is based on random mutagenesis of the RNA target followed by functional selection and next-generation sequencing. Our analytical approach allows the recovery of quantitative binding parameters and permits the identification of base-pairing partners directly from the sequencing data. We used this method to map the binding site of the human immunodeficiency virus-1 (HIV-1) Pr55(Gag) protein on the viral genomic RNA in vitro, and showed that, by analyzing permitted base-pairing patterns, we could model RNA structure motifs that are crucial for protein binding.

Snap

‘Snap’ deploys the queer cliché of becoming-sailor as a trope for recognition in the amorous encounter and literalises the ‘copycat’ as its catalyst. As Girard argues (1973), the human is foremost mimetic: this story makes its claim for originality and authenticity of connection through the playful recycling of cliché.‘Snap’ eschews the relative affectlessness of some metafiction by staging an amorous approach under the shadow of mortality. It exploits the liminal moment of modernist short fiction to summon the ‘manifold’ of experience. Here, love opens a space of intertextual esonance (Costello 2007), including motifs of Genet (masquerade), Duras (haunting) and Maurice Blanchot (the infinite approach), by writing the threshold of encounter as the intensive silence of wond