Insertion and activation of functional Bacteriorhodopsin in a floating bilayer

Recent progress in application of surface X-ray scattering techniques to soft interfacial films

X-ray reflection (XR) and surface grazing incidence X-ray diffraction GIXD) techniques have traditionally been used to evaluate the structure of soft interfacial films. In recent years, the use of synchrotron radiation and two-dimensional detectors has enabled high resolution and high speed measurements of interfacial films, which makes it possible to evaluate more detailed and complex interfacial film structures and adsorption dynamics. In this review, we will provide an overview of recent progress in structural characterization of simple oil/water interfaces, interfacial films of biologically relevant materials, oil/water interfaces for extraction of rare metal ions, and adsorption of nanoparticles. Examples of the application of time-resolved XR methods and surface sensitive techniques such as GISAXS and surface X-ray fluorescence analysis will also be presented.

Cry11Aa and Cyt1Aa exhibit different structural orders in crystal topography

Cry11Aa and Cyt1Aa are two pesticidal toxins produced by Bacillus thuringiensis subsp. israelensis. To improve our understanding of the nature of their oligomers in the toxic actions and synergistic effects, we performed the atomic force microscopy to probe the surfaces of their natively grown crystals, and used the L-weight filter to enhance the structural features. By L-weight filtering, molecular sizes of the Cry11Aa and Cyt1Aa monomers obtained are in excellent agreement with the three-dimensional structures determined by x-ray crystallography. Moreover, our results show that the layered feature of a structural element distinguishes the topographic characteristics of Cry11Aa and Cyt1Aa crystals, suggesting that the Cry11Aa toxin has a better chance than Cyt1Aa for multimerization and therefore cooperativeness of the toxic actions.

Engineered Bacteriorhodopsin May Induce Lung Cancer Cell Cycle Arrest and Suppress Their Proliferation and Migration

Highly expressible bacteriorhodopsin (HEBR) is a light-triggered protein (optogenetic protein) that has seven transmembrane regions with retinal bound as their chromophore to sense light. HEBR has controllable photochemical properties and regulates activity on proton pumping. In this study, we generated HEBR protein and incubated with lung cancer cell lines (A549 and H1299) to evaluate if there was a growth-inhibitory effect with or without light illumination. The data revealed that the HEBR protein suppressed cell proliferation and induced the G0/G1 cell cycle arrest without light illumination. Moreover, the migration abilities of A549 and H1299 cells were reduced by ~17% and ~31% after incubation with HEBR (40 μg/mL) for 4 h. The Snail-1 gene expression level of the A549 cells was significantly downregulated by ~50% after the treatment of HEBR. In addition, HEBR significantly inhibited the gene expression of Sox-2 and Oct-4 in H1299 cells. These results suggested that the HEBR protein may inhibit cell proliferation and cell cycle progression of lung cancer cells, reduce their migration activity, and suppress some stemness-related genes. These findings also suggested the potential of HEBR protein to regulate the growth and migration of tumor cells, which may offer the possibility for an anticancer drug.