Large scale localization of protein phosphorylation by use of electron capture dissociation mass spectrometry.

We used on-line electron capture dissociation (ECD) for the large scale identification and localization of sites of phosphorylation. Each FT-ICR ECD event was paired with a linear ion trap collision-induced dissociation (CID) event, allowing a direct comparison of the relative merits of ECD and CID for phosphopeptide identification and site localization. Linear ion trap CID was shown to be most efficient for phosphopeptide identification, whereas FT-ICR ECD was superior for localization of sites of phosphorylation. The combination of confident CID and ECD identification and confident CID and ECD localization is particularly valuable in cases where a phosphopeptide is identified just once within a phosphoproteomics experiment

Structure of Tagatose-1,6-bisphosphate Aldolase. Insight into chiral discrimination, mechanism, and specificity of class II aldolases

Tagatose-1,6-bisphosphate aldolase (TBPA) is a tetrameric class II aldolase that catalyzes the reversible condensation of dihydroxyacetone phosphate with glyceraldehyde 3-phosphate to produce tagatose 1,6-bisphosphate. The high resolution (1.45 Å) crystal structure of the Escherichia coli enzyme, encoded by the agaY gene, complexed with phosphoglycolohydroxamate (PGH) has been determined. Two subunits comprise the asymmetric unit, and a crystallographic 2-fold axis generates the functional tetramer. A complex network of hydrogen bonds position side chains in the active site that is occupied by two cations. An unusual Na(+) binding site is created using a interaction with Tyr(183) in addition to five oxygen ligands. The catalytic Zn(2+) is five-coordinate using three histidine nitrogens and two PGH oxygens. Comparisons of TBPA with the related fructose-1,6-bisphosphate aldolase (FBPA) identifies common features with implications for the mechanism. Because the major product of the condensation catalyzed by the enzymes differs in the chirality at a single position, models of FBPA and TBPA with their cognate bisphosphate products provide insight into chiral discrimination by these aldolases. The TBPA active site is more open on one side than FBPA, and this contributes to a less specific enzyme. The availability of more space and a wider range of aldehyde partners used by TBPA together with the highly specific nature of FBPA suggest that TBPA might be a preferred enzyme to modify for use in biotransformation chemistry

VEGAS: A VST Early-type GAlaxy Survey. II. Photometric study of giant ellipticals and their stellar halos

Observations of diffuse starlight in the outskirts of galaxies are thought to be a fundamental source of constraints on the cosmological context of galaxy assembly in the $\Lambda$CDM model. Such observations are not trivial because of the extreme faintness of such regions. In this work, we investigate the photometric properties of six massive early type galaxies (ETGs) in the VEGAS sample (NGC 1399, NGC 3923, NGC 4365, NGC 4472, NGC 5044, and NGC 5846) out to extremely low surface brightness levels, with the goal of characterizing the global structure of their light profiles for comparison to state-of-the-art galaxy formation models. We carry out deep and detailed photometric mapping of our ETG sample taking advantage of deep imaging with VST/OmegaCAM in the g and i bands. By fitting the light profiles, and comparing the results to simulations of elliptical galaxy assembly, we identify signatures of a transition between "relaxed" and "unrelaxed" accreted components and can constrain the balance between in situ and accreted stars. The very good agreement of our results with predictions from theoretical simulations demonstrates that the full VEGAS sample of $\sim 100$ ETGs will allow us to use the distribution of diffuse light as a robust statistical probe of the hierarchical assembly of massive galaxies.Comment: Accepted for publication in Astronomy & Astrophysic

Exacerbated neuronal ceroid lipofuscinosis phenotype in Cln1/5 double-knockout mice

Peer reviewe

Sphingosine kinase 1 overexpression induces MFN2 fragmentation and alters mitochondrial matrix Ca2+ handling in HeLa cells

Sphingosine kinase 1 (SKI) converts sphingosine to the bioactive lipid sphingosine 1-phosphate (SIP). SW binds to G-protein-coupled receptors (S1PR(1-5)) to regulate cellular events, including Ca2+ signaling. The SK1/S1P axis and Ca2+ signaling both play important roles in health and disease. In this respect, Ca2+ microdomains at the mitochondria-associated endoplasmic reticulum (ER) membranes (MAMs) are of importance in oncogenesis. Mitofusin 2 (MFN2) modulates ER-mitochondria contacts, and dysregulation of MFN2 is associated with malignancies. We show that overexpression of SKI augments agonist-induced Ca2+ release from the ER resulting in increased mitochondria] matrix Ca2+. Also, overexpression of SK1 induces MFN2 fragmentation, likely through increased calpain activity. Further, expressing putative calpain-cleaved MFN2 N- and C-terminal fragments increases mitochondrial matrix Ca2+ during agonist stimulation, mimicking the SK1 overexpression in cells. Moreover, SK1 overexpression enhances cellular respiration and cell migration. Thus, SK1 regulates MFN2 fragmentation resulting in increased mitochondrial Ca2+ and downstream cellular effects.Peer reviewe

A CD21 low phenotype, with no evidence of autoantibodies to complement proteins, is consistent with a poor prognosis in CLL.

B-cell chronic lymphocytic leukemia (CLL) is characterized by differential BCR signaling and autoimmune complications. Complement modulates B-cell function via C3d and CD21 cross-linked to the B-cell receptor (BCR). We hypothesized that CD21 contributes to BCR signaling and participates in the autoimmunity associated with CLL. We analyzed CD21 expression on 106 CLL patient samples and matched serum from 50 patients for the presence of soluble CD21 and autoantibodies to CR2, CR1, MCP and FH. CD21 expression on CLL B-cells was significantly lower than that expressed on B-cells from age-matched controls (P < 0.0001) and was inversely correlated with soluble CD21 (r2 = –0.41). We found no evidence of autoantibody to any complement regulator. Low CD21 expression correlated to prognostic subsets of CLL patients, i.e. cases with unmutated IGHV genes (P = 0.0006), high CD38 (P = 0.02) and high ZAP70 expression (P = 0.0017). Low CD21 expression was inversely correlated to the levels of phosphotyrosine induced in CLL cells following BCR ligation with αIgM (r2=–0.21). Importantly, lower CD21 expression was also predictive for reduced overall survival (P = 0.005; HR = 2.7). In conclusion, we showed that reduced expression of CD21 on CLL B-cells appears functionally relevant and was associated with poor clinical outcomes

The UK overseas territories: A decade of progress and prosperity?

This article analyses the relationship between the UK and its Overseas Territories since the publication of the 1999 White Paper Partnership for Progress and Prosperity. The article considers the efforts by the UK government to improve links with the territories via a new partnership based on mutual obligations and responsibilities. It focuses on the two most important aspects of the White Paper - governance and economic growth and sustainability. Much has been achieved, but fundamental structural problems in the relationship remain unattended. The article concludes by recommending how the relationship can be improved over the coming years. © 2011 Taylor & Francis