A strain-specific alteration of proteomic expression in mouse liver fructose 1,6-bisphosphatase isoforms by alcohol

To study alcohol-related metabolism across inbred mouse strains, liver tissues from C57BL/6J (B6, an alcohol-preferring mouse) and DBA/2J (D2, an alcohol-avoiding strain) mice were analyzed for proteomic expression patterns over time after a single-dose of alcohol (1.5 g/kg ingestion). Despite no significant difference in the elimination rate of blood ethanol, two-dimensional electrophoresis gel images of liver proteins showed that proteins in B6 mice exhibited faster response and more quantitative (spot numbers) and qualitative (spot densities) changes than in D2 mice. Among the differentially expressed metabolic enzymes, four variants (alpha, beta, gamma and delta) of fructose 1,6-bisphosphatase (FBPase), a key regulatory gluconeogenic enzyme, showed remarkable changes in expression with time across the strains. The degree of spot alteration in alpha- and gamma-variants of FBPase in B6 mice was much higher than in D2 mice, while the beta- and delta-forms were not changed as much. Mass spectrometry (MS) analysis showed that the 1714.9 +/- 1 mass peak from the alpha- and gamma-variants of FBPase was much stronger than that of the beta- and delta-variants in both strains regardless of spot density. This MS peak contains 2-ANHAPFETDISTLTR-16, located at the N-terminal of FBPase, where the N-terminal alanine was found to be trimethylated. Thus, we propose this N-terminal fragment as a potential site for enzyme modification in response to ethanol, allowing for differences in two-dimensional gel spot intensity of variants of FBPase in the two mouse strains.     

Potential and practical adrenomedullary PET radiopharmaceuticals as an alternative to m-iodobenzylguanidine: m-(omega-[18F]fluoroalkyl)benzylguanidines

To investigate adrenomedullary radiopharmaceuticals for positron emission tomography (PET), we have developed no-carrier-added m-(omega-[18F]fluoroalkyl)benzylguanidines. m-(omega-[18F]Fluoroalkyl)benzylguanidines were prepared in two steps starting from N,N'-bis(tert-butyloxycarbonyl)-N' '-(omega-methanesulfonyloxyalkyl)benzylguanidines in 20-30% radiochemical yields (decay corrected for 100 min) and with high radiochemical purity (>97%) and shown to be stable (>90%) in an in vitro metabolic stability assay. The binding of m-(3-[18F]fluoropropyl)benzylguanidine ((18F]3) to SK-N-SH human neuroblastoma cells was temperature dependent, and binding levels at 4 degrees C were reduced to half of that at 37 degrees C, which was similar to the reduction rate observed for [123I]MIBG. Tissue distribution studies in mice showed the highest uptake in the adrenals (%ID/g = 27.2 +/- 5.0%) with relatively high uptake in the myocardium (%ID/g = 9.3 +/- 0.5%). The results suggest that this radiotracer holds promise as a useful adrenomedullary radiopharmaceutical for PET imaging.     

Interaction of the DnaK and DnaJ chaperone system with a native substrate,P1 RepA

DnaK, the Hsp70 chaperone of Escherichia coli interacts with protein substrates in an ATP-dependent manner, in conjunction with DnaJ and GrpE co-chaperones, to carry out protein folding, protein remodeling, and assembly and disassembly of multisubunit protein complexes. To understand how DnaJ targets specific proteins for recognition by the DnaK chaperone system, we investigated the interaction of DnaJ and DnaK with a known natural substrate, bacteriophage P1 RepA protein. By characterizing RepA deletion derivatives, we found that DnaJ interacts with a region of RepA located between amino acids 180 and 200 of the 286-amino acid protein. A peptide corresponding to amino acids 180-195 inhibited the interaction of RepA and DnaJ. Two site-directed RepA mutants with alanine substitutions in this region were about 4-fold less efficiently activated for oriP1 DNA binding by DnaJ and DnaK than wild type RepA. We also identified by deletion analysis a site in RepA, in the region of amino acids 35-49, which interacts with DnaK. An alanine substitution mutant in amino acids 36-39 was constructed and found defective in activation by DnaJ and DnaK. Taken together the results suggest that DnaJ and DnaK interact with separate sites on RepA.     

Structural and functional implications of C-terminal regions of alpha-synuclein

Aggregation of alpha-synuclein is thought to play a major role in the pathogenesis of Parkinson's disease (PD), which is characterized by the presence of intracytoplasmic Lewy bodies (LB) in the brain. alpha-Synuclein and its deletion mutants are largely unfolded proteins with random coil structures as revealed by CD spectra, fluorescence spectra, gel filtration chromatography, and ultracentrifugation. On the basis of its highly unfolded and flexible conformation, we have investigated the chaperone-like activity of alpha-synuclein in vitro. In our experiments, alpha-synuclein inhibited the aggregation of model substrates and protected the catalytic activity of alcohol dehydrogenase and rhodanese during heat stress. In addition, alpha-synuclein inhibited the initial aggregation of reduced/denatured lysozyme on the refolding pathway. Interestingly, deletion of the C-terminal regions led to the abolishment of chaperone activity, although largely unstructured conformations are maintained. Moreover, alpha-synuclein could inhibit the aggregation of various Escherichia coli cellular proteins during heat stress, and C-terminal deletion mutants could not provide any protection to these cellular proteins. Results with synthetic C-terminal peptides and C-terminal deletion mutants suggest that the second acidic repeat, (125)YEMPSEEGYQDYEPEA(140), is important for the chaperone activity of alpha-synuclein, and C-terminal deletion leads to the facilitated aggregation with the elimination of chaperone activity.     

Oxidant and SDS-stable alkaline protease from Bacillus clausii I-52: production and some properties

AIMS: An investigation was carried out on an oxidative and SDS-stable alkaline protease secreted by Bacillus clausii of industrial significance. METHODS AND RESULTS: Maximum enzyme activity was produced when the bacterium was grown in the medium containing (g l-1): soyabean meal, 15; wheat flour, 10; liquid maltose, 25; K2HPO4, 4; Na2HPO4, 1; MgSO4.7H2O, 0.1; Na2CO3, 6. The enzyme has an optimum pH of around 11 and optimum temperature of 60 degrees C. The alkaline protease showed extreme stability towards SDS and oxidizing agents, which retained its activity above 75 and 110% on treatment for 72 h with 5% SDS and 10% H2O2, respectively. Inhibition profile exhibited by phenylmethylsulphonyl fluoride suggested that the protease from B. clausii belongs to the family of serine proteases. CONCLUSIONS: Bacillus clausii produced high levels of an extracellular protease having high stability towards SDS and H2O2. SIGNIFICANCE AND IMPACT OF THE STUDY: The alkaline protease from B. clausii I-52 is significant for an industrial perspective because of its ability to function in broad pH and temperature ranges in addition to its tolerance and stability in presence of an anionic surfactant, like SDS and oxidants like peroxides and perborates. The enzymatic properties of the protease also suggest its suitable application as additive in detergent formulations.