Shotgun Proteomics Revealed Preferential Degradation of Misfolded In Vivo Obligate GroE Substrates by Lon Protease in Escherichia coli

The Escherichia coli chaperonin GroEL/ES (GroE) is one of the most extensively studied molecular chaperones. So far, ~80 proteins in E. coli are identified as GroE substrates that obligately require GroE for folding in vivo. In GroE-depleted cells, these substrates, when overexpressed, tend to form aggregates, whereas the GroE substrates expressed at low or endogenous levels are degraded, probably due to misfolded states. However, the protease(s) involved in the degradation process has not been identified. We conducted a mass-spectrometry-based proteomics approach to investigate the effects of three ATP-dependent proteases, Lon, ClpXP, and HslUV, on the E. coli proteomes under GroE-depleted conditions. A label-free quantitative proteomic method revealed that Lon protease is the dominant protease that degrades the obligate GroE substrates in the GroE-depleted cells. The deletion of DnaK/DnaJ, the other major E. coli chaperones, in the ∆lon strain did not cause major alterations in the expression or folding of the obligate GroE substrates, supporting the idea that the folding of these substrates is predominantly dependent on GroE.     

Laser spectroscopy of the antiprotonic helium atom–molecule {\bar pHe}^+

The metastable antiprotonic helium atom–molecule (in short, atomcule), , which was discovered in 1991 as being the cause of the anomalous longevity of antiprotons with an overall lifetime of about 3 μs, now provides an exotic playground for laser spectroscopy, helped by the existence of numerous long lived states with 1–2 μs lifetimes. This three body system is characterized by a large angular momentum l ∼ 38 of coupled with the electron in the 1s ground orbital, and looks like an exotic hydrogen isotope with many different “nuclear states” as well as an exotic molecule with two centers (He²⁺ and ). So far, a number of laser resonance transitions have been identified. The present talk will cover the following topics: (1) high precision spectroscopy in comparison with three body theories involving the relativistic effect and QED, and (2) hyperfine structure of ;laser-microwave triple resonance. This revised version was published online in August 2006 with corrections to the Cover Date.     

Coolant Wetting Simulation on Simplified Stator Coil Model by the Phase-Field Lattice Boltzmann Method

Stator coils of automobiles in operation generate heat and are cooled by coolant poured from above. The flow characteristic of the coolant depends on the coil structure, flow condition, solid–fluid interaction, and fluid property, which has not been clarified due to its complexities. Since straight coils are aligned and layered with an angle at the coolant-touchdown region, the coil structure is simplified to a horizontal square rod array referring to an actual coil size. To obtain the flow and wetting characteristics, two-phase fluid flow simulations are conducted by using the phase-field lattice Boltzmann method. First, the flow onto the single-layered rod array is discussed. The wetting area is affected both by the rod gap and the wettability, which is normalized by the gap and the averaged boundary layer thickness. Then, the flow onto the multi-layered rod arrays is investigated with different rod gaps. The top layer wetting becomes longitudinal due to the reduction of the flow advection by the second layer. The wetting area jumps up at the second layer and increases proportionally to the below layers. These become remarkable at the narrow rod gap case, and finally, the dimensionless wetting area is discussed at each layer.     

Controlled Synthesis of Diphosphine-Protected Gold Cluster Cations Using Magnetron Sputtering Method

We demonstrated, for the first time, atomically precise synthesis of gold cluster cations by magnetron sputtering of a gold target onto a polyethylene glycol (PEG) solution of 1,3-bis(diphenylphosphino)propane (Ph₂PCH₂CH₂CH₂PPh₂, dppp). UV-vis absorption spectroscopy and electrospray ionization mass spectrometry revealed the formation of cationic species, such as [Au(dppp)_n]⁺ (n = 1, 2), [Au₂(dppp)_n]²⁺ (n = 3, 4), [Au₆(dppp)_n]²⁺ (n = 3, 4), and [Au₁₁(dppp)₅]³⁺. The formation of [Au(dppp)₂]⁺ was ascribed to ionization of Au(dppp)₂ by the reaction with PEG, based on its low ionization energy, theoretically predicted, mass spectrometric detection of deprotonated anions of PEG. We proposed that [Au(dppp)₂]⁺ cations thus formed are involved as key components in the formation of the cluster cations.     

Omaezallene from Red Alga Laurencia sp.: Structure Elucidation,Total Synthesis,and Antifouling Activity

Natural antifouling products have been the subject of considerable attention. We screened marine algae for antifouling activity and discovered omaezallenes, the new bromoallene‐containing natural products isolated from the red alga Laurencia sp. Described is the isolation, structure elucidation, and total syntheses of omaezallenes. The relative and absolute configurations of natural omaezallenes were unambiguously established through total synthesis. The antifouling activities and ecotoxicity of omaezallenes were also evaluated.     

Halogenated cladosporols produced by the sodium halide-supplemented fermentation of the plant-associated fungus Cladosporium sp. TMPU1621

A new cladosporol derivative, 2-chloro-cladosporol D (6), was isolated together with known cladosporol (1), cladosporols B–D (2–4), and cladosporol F (5) from the culture broth of plant-associated Cladosporium sp. TMPU1621. The structure of 6 was elucidated from spectroscopic analyses including NMR and MS data. The productivity of 6 increased in 3% NaCl-supplemented medium; therefore, fermentation of the producing fungus TMPU1621 with 3% NaBr was investigated, leading to the induced production of a new halogenated cladosporol, 2-bromo-cladosporol D (7). Compound 2 showed the lowest MIC values of 3.13 and 12.5?μg/mL against two MRSA strains, ATCC43300 and ATCC700698, respectively.     

Optical detection of DNA translocation through silicon nanopore by ultraviolet light

In this paper, we propose a new optical detection scheme for nanopore-based DNA sequencing with high resolution towards eventual base identification. We use ultraviolet light for excitation of a fluorescent probe attached to DNA and a nanopore in the silicon membrane that has a significantly large refractive index and an extinction coefficient at ultraviolet wavelengths. In this study, numerical electromagnetic simulation revealed that the z-polarization component (perpendicular to the membrane plane) of the electric field was dominant near the nanopore and generated a large electric field gradient at the nanopore exit, typically with a decay length of 2 nm for a nanopore with diameter of 7 nm. The large extinction coefficient contributed to reduction in background noise coming from fluorophore-labeled DNA strands that remain behind the membrane (the cis side of the membrane). We observed a high signal-to-noise ratio of single DNA translocation events under the application of an electric field.     

Preparation of poly(ether ketone)s derived from 2,5‐furandicarboxylic acid via nucleophilic aromatic substitution polymerization

From the viewpoint of the suppression of the petroleum consumption, aromatic poly(ether ketone)s (PEKs) were prepared by the nucleophilic aromatic substitution polymerization of 2,5‐bis(4‐fluorobenzoyl)furan (BFBF) synthesized from biomass and aromatic bisphenols. The model reaction of BFBF and p‐methoxyphenol revealed that BFBF possessed enough reactivity for the nucleophilic aromatic substitution reactions. The polymerizations of BFBF and aromatic bisphenols afforded high molecular weight polymers with good yields in N‐methylpyrrolidone and diphenyl sulfone for several hours. The longer polymerization time brought about the formation of insoluble parts in any solvents and reduction of molecular weight. The obtained PEKs were thermoplastics and exhibited good thermal stability, mechanical properties, and chemical resistance comparable to common high‐performance polymers. The thermal properties were tunable with the structure of bisphenols. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3094–3101