The glycation site specificity of human serum transferrin is determinant for the protein functional impairment under elevated glycemic conditions.
The mechanisms involving iron toxicity in diabetes mellitus are not completely understood. However, the spontaneous reaction of reducing sugars with protein amino groups, known as glycation, has been shown to compromise the action of transferrin (Tf), the systemic iron transporter. In order to understand the structural alterations that impair its function, Tf was glycated in vitro and the modification sites were determined by mass spectrometry (MS). Iron binding to glycated Tf was assessed and a computational approach has been conducted to study how glycation influences the iron-binding capacity of this protein.
Glycated ...
Source: BJ Disease - April 10, 2014 Category: Biochemistry Authors: A M. N. Silva, P R. H. Sousa, J T. S. Coimbra, N F. Brás, R Vitorino, P A. Fernandes, M João Ramos, M Rangel, P Domingues Tags: BJ Biomolecules Source Type: research
Retinal metabolism in human retina induces the formation of an unprecedented lipofuscin fluorophore "pdA2E"
In this study, we identified a novel fluorescent lipofuscin component in human and bovine RPEs. Using one- and two-dimensional NMR and mass spectrometry, we confirmed the structure of this pigment and called it pdA2E. It exhibits absorbance maxima at 492 and 342 nm and is susceptible to photocatalytic isomerization and oxidation. This fluorophore was also detected in the eyecup extracts of Abca4-/-Rdh8-/-mice, an AMD/recessive Stargardt model. Excess amassing of pdA2E within RPE cells caused significant cell viability loss and membrane damage. The formation of pdA2E occurred when all-trans-retinal (atRAL) reacted with exce...
Source: BJ Disease - April 9, 2014 Category: Biochemistry Authors: Y Wu, Q Jin, K Yao, J Zhao, J Chen, X Wu, L Gan, J Li, X Song, X Liu, X Cai Tags: BJ Metabolism Source Type: research
Parkin is activated by PINK1-dependent phosphorylation of ubiquitin at Serine65
In conclusion, our findings reveal that PINK1 controls Parkin E3 ligase activity not only by phosphorylating Parkin at Ser65 but also by phosphorylating ubiquitin at Ser65. We propose that phosphorylation of Parkin at Ser65 serves to prime the E3 ligase enzyme for activation by ubiquitinPhospho-Ser65, suggesting that small molecules that mimic ubiquitinPhospho-Ser65 could hold promise as novel therapies for Parkinson’s. (Source: BJ Disease)
Source: BJ Disease - March 25, 2014 Category: Biochemistry Authors: A Kazlauskaite, C Kondapalli, R Gourlay, D G Campbell, M Ritorto, K Hofmann, D R Alessi, A Knebel, M Trost, M M.K. Muqit Tags: BJ Signal Source Type: research
Kinase and channel activity of TRPM6 are coordinated by a dimerization motif and pocket interaction
Mutations in the gene that encodes the atypical channel-kinase Transient receptor potential melastatin 6 (TRPM6) cause hypomagnesemia with secondary hypocalcemia (HSH), a disorder characterized by defective intestinal Mg2+ transport and impaired renal Mg2+ reabsorption. TRPM6, together with its homologue TRPM7, are unique proteins as they combine an ion channel domain with a carboxy-terminally fused protein kinase domain. How TRPM6 channel and kinase activity are linked is unknown. Previous structural analysis revealed that TRPM7 possesses a non-catalytic dimerization motif preceding the kinase domain. This i...
Source: BJ Disease - March 21, 2014 Category: Biochemistry Authors: J van der Wijst, M G. Blanchard, H I. Woodroof, T J. Macartney, R Gourlay, J G. Hoenderop, R J. Bindels, D R. Alessi Tags: BJ Signal Source Type: research
Polyglycine hydrolases secreted by Pleosporineae fungi that target the linker region of plant class IV chitinases
Chitinase modifying proteins (cmps) are fungal proteases that truncate plant class IV chitinases by cleaving near their amino termini. We previously described Fv-cmp, a fungalysin protease that cleaves a conserved glycine-cysteine bond within the hevein domain. Here we describe a new type of cmp—polyglycine hydrolases—as proteases that selectively cleave glycine-glycine peptide bonds within the polyglycine linker of plant class IV chitinases. Polyglycine hydrolases were purified from Cochliobolus carbonum (syn. Bipolaris zeicola, Bz-cmp) and Epicoccum sorghi (syn. Phoma sorghina, Es-cmp) and were shown to cle...
Source: BJ Disease - March 17, 2014 Category: Biochemistry Authors: T A Naumann, D T Wicklow, N P. J. Price Tags: BJ Plant Source Type: research
Altered native stability is the dominant basis for susceptibility of {alpha}1-antitrypsin mutants to polymerisation
Serpins are protease inhibitors whose most stable state is achieved upon transition of a central five-stranded β-sheet to a six-stranded form. Mutations, low pH, denaturants, and elevated temperatures promote this transition, which can result in a growing polymer chain of inactive molecules. Different types of polymer are possible, but experimentally, only heat has been shown to generate polymers in vitro consistent with ex vivo pathological specimens. Many mutations that alter the rate of heat-induced polymerisation have been described, but interpretation is problematic, because discrimination is lacking between th...
Source: BJ Disease - February 20, 2014 Category: Biochemistry Authors: J A. Irving, I Haq, J A. Dickens, S V. Faull, D A. Lomas Tags: BJ Disease Source Type: research
A novel p38 MAPK docking groove-targeted compound is a potent inhibitor of inflammatory hyperalgesia
The mitogen activated protein kinase (MAPK) p38 is an important mediator of inflammation and of inflammatory and neuropathic pain. We recently described that docking-groove dependent interactions are important for p38 MAPK-mediated signal transduction. Thus, virtual screening was performed to identify putative docking groove-targeted p38 MAPK inhibitors. Several compounds of the benzooxadiazol family were identified with low micromolar inhibitory activity both in a p38 MAPK activity assay, and in THP-1 human monocytes acting as inhibitors of LPS-induced TNFα secretion. Positions 2 and 5 in the phenyl ring are essent...
Source: BJ Disease - February 11, 2014 Category: Biochemistry Authors: H L.D.M. Willemen, P M. Campos, E Lucas, A Morreale, R Gil-Redondo, J Agut, F V. González, P Ramos, C Heijnen, F Mayor Jr., A Kavelaars, C Murga Tags: BJ Signal Source Type: research
The HicA toxin from Burkholderia pseudomallei has a role in persister cell formation
Toxin-antitoxin (TA) systems are widely distributed amongst bacteria and are associated with the formation of antibiotic tolerant (persister) cells that may have involvement in chronic and recurrent disease. We show that over- expression of the Burkholderia pseudomallei HicA toxin causes growth arrest and increases the number of persister cells tolerant to ciprofloxacin or ceftazidime. Furthermore, our data show that persistence towards ciprofloxacin or ceftazidime can be differentially modulated depending on the level of induction of HicA expression. Deleting the hicAB locus from B. pseudomallei K96243 significantly reduc...
Source: BJ Disease - February 7, 2014 Category: Biochemistry Authors: A Butt, V A. Higman, C Williams, M P. Crump, C M. Hemsley, N Harmer, R W. Titball Tags: BJ Disease Source Type: research
Singlet oxygen effects on lipid membranes: implication on broad range viral fusion inhibitors mechanism of action
It was recently reported that a new aryl methyldiene rhodanine derivative, LJ001, and oxazolidine-2,4-dithione, JL103, act on the viral membrane, inhibiting its fusion with a target cell membrane. The aim of this work was to study the interactions of these two active compounds and an inactive analog used as negative control, LJ025, with biological membrane models, in order to clarify the mechanism of action at the molecular level of these new broad-range enveloped viruses entry inhibitors. Fluorescence spectroscopy was used to quantify the partition and determine the location of the molecules on membranes. The ability of t...
Source: BJ Disease - January 24, 2014 Category: Biochemistry Authors: A Hollmann, M A.R.B. Castanho, B Lee, N C. Santos Tags: BJ ChemBio Source Type: research
Biochemical and genetic characterisation of Trypanosoma cruzi N-myristoyltransferase
Co- and post-translational N-myristoylation is known to play a role in the correct subcellular localisation of specific proteins in eukaryotes. The enzyme that catalyses this reaction, N-myristoyltransferase (NMT), has been pharmacologically validated as a drug target in the African trypanosome, Trypanosoma brucei. Here we evaluate NMT as a potential drug target in Trypanosoma cruzi,the causative agent of Chagas disease, using chemical and genetic approaches. Replacement of both allelic copies of TcNMT was only possible in the presence of a constitutively expressed ectopic copy of the gene, indicating that this geneis esse...
Source: BJ Disease - January 21, 2014 Category: Biochemistry Authors: A J. Roberts, L S. Torrie, S Wyllie, A H. Fairlamb Tags: BJ Metabolism Source Type: research
Niemann-Pick disease type C2 protein induces triglyceride accumulation in silkworm and mammalian cell lines
Silkworm hemolymph induced both the cessation of growth and an increase in triglyceride storage in BmN4 cells. We purified the growth inhibitory factor from the silkworm hemolymph and identified this protein as the Bombyx mori Promoting Protein, an ortholog of Niemann-Pick disease type C2 (NPC2) protein. Recombinant silkworm NPC2 inhibited cellular proliferation and increased triglyceride accumulation in BmN4 cells. Injection of either the recombinant protein or antiserum of NPC2 into living silkworms increased or decreased, respectively, triglyceride levels in the fat body. A mutation that depletes the cholesterol-binding...
Source: BJ Disease - January 20, 2014 Category: Biochemistry Authors: T Adachi, K Ishii, Y Matsumoto, Y Hayashi, H Hamamoto, K Sekimizu Tags: BJ Metabolism Source Type: research
Frataxin-bypassing Isu1: characterization of the bypass activity in cells and mitochondria
Frataxin is a conserved mitochondrial protein, and deficiency underlies the neurodegenerative disease Friedreich's ataxia. Frataxin interacts with the core machinery for Fe-S cluster assembly in mitochondria. Recently we reported that in frataxin deleted yeast strains, a spontaneously occurring mutation in one of two genes encoding redundant Isu scaffold proteins, bypassed the mutant phenotypes. Here we created strains expressing a single scaffold protein, either Isu1 or the bypass mutant M107I Isu1. Results show that in the frataxin deletion strain expressing the bypass mutant Isu1, cell growth, Fe-S cluster protein activ...
Source: BJ Disease - January 16, 2014 Category: Biochemistry Authors: H Yoon, S A.B. Knight, A Pandey, J Pain, Y Zhang, D Pain, A Dancis Tags: BJ Metabolism Source Type: research
Mechanistic insight into the reaction catalysed by bacterial type II dehydroquinases
The type II dehydroquinase (DHQ2), which is an essential enzyme in Helicobacter pylori and Mycobacterium tuberculosis, is recognized to be an attractive target for the development of new antibacterial agents. Computational and biochemical studies that help understand in atomic detail the catalytic mechanism these bacterial enzymes are reported. Asp89*/Asp88* from a symmetry-related neighboring enzyme subunit proved to be the residue responsible for the deprotonation of the essential tyrosine to afford the catalytic tyrosinate, which triggers the enzymatic process. The essentiality of this residue is supported by results fr...
Source: BJ Disease - January 7, 2014 Category: Biochemistry Authors: C Coderch, E Lence, A Peón, H Lamb, A Hawkins, F Gago, C González-Bello Tags: BJ Biomolecules Source Type: research
Physiological expression of the PI3K activating mutation Pik3caH1047R combines with Apc loss to promote development of invasive intestinal adenocarcinomas in mice
PIK3CA, the gene encoding the p110α catalytic subunit of phosphoinositide 3-kinase (PI3K), is mutated in around 20% of sporadic colorectal cancers (CRCs) but the role of these mutations in the pathogenesis of CRC remains unclear. We used a novel mouse model to investigate the role of Pik3caH1047R mutation, the most common PIK3CA mutation in CRC, during the development and progression of intestinal cancer. Our results demonstrate that Pik3caH1047R, when expressed at physiological levels, is insufficient to initiate intestinal tumourigenesis. However,in the context of Apc loss, which is observed in 80% of CRCs and by ...
Source: BJ Disease - December 9, 2013 Category: Biochemistry Authors: L M. Hare, T J. Phesse, P M. Waring, K G. Montgomery, K M. Kinross, K Mills, V Roh, J K. Heath, R G. Ramsay, M Ernst, W A. Phillips Tags: BJ Disease Source Type: research
A structure-guided fragment-based approach for the discovery of allosteric inhibitors targeting the lipophilic binding site of transcription factor EthR
We report the identification of a 1 µM affinity ligand obtained by structure-guided fragment linking. (Source: BJ Disease)
Source: BJ Disease - December 6, 2013 Category: Biochemistry Authors: S Surade, N Ty, N Hengrung, B Lechartier, S T. Cole, C Abell, T L Blundell Tags: BJ ChemBio Source Type: research
