Hydrogen-deuterium exchange profiles of polyubiquitin fibrils

Ubiquitin and its polymeric forms are conjugated to intracellular proteins to regulate diverse intracellular processes. Intriguingly, polyubiquitin has also been identified as a component of pathological protein aggregates associated with Alzheimer’s disease and other neurodegenerative disorders. We recently found that polyubiquitin can form amyloid-like fibrils, and that these fibrillar aggregates can be degraded by macroautophagy. Although the structural properties appear to function in recognition of the fibrils, no structural information on polyubiquitin fibrils has been reported so far. Here, we identify the core of M1-linked diubiquitin fibrils from hydrogen-deuterium exchange experiments using solution nuclear magnetic resonance (NMR) spectroscopy. Intriguingly, intrinsically flexible regions became highly solvent-protected in the fibril structure. These results indicate that polyubiquitin fibrils are formed by inter-molecular interactions between relatively flexible structural components, including the loops and edges of secondary structure elements

Porous Surface Structure Fabricated by Breath Figures that Suppresses <i>Pseudomonas aeruginosa</i> Biofilm Formation

As colonizers of medical-device surfaces, Pseudomonas aeruginosa strains present a serious source of infection and are of major concern. In this study, we fabricated films with porous surfaces by breath figures that disturb mergence by bacterial attachment, thereby impeding biofilm development. Previous studies have shown that microtopography prevents the development of P. aeruginosa biofilms. Accordingly we indented surfaces with patterns of micrometer-sized pores using breath figures at ordinary temperatures and pressures. The antimicrobial effect of surface figures was experimentally investigated by controlling the surface structure. The results suggested that pores of 5–11 μm in diameter effectively inhibit bacterial activity. It appears that biofilm development is precluded by the decreased contact area between the films and bacteria