Carbon nanotubes have specific properties that make them potentially useful in biomedicine and biotechnology. However, carbon nanotubes may themselves be toxic, making it imperative to understand... Show moreCarbon nanotubes have specific properties that make them potentially useful in biomedicine and biotechnology. However, carbon nanotubes may themselves be toxic, making it imperative to understand how carbon nanotubes interact with biomolecules such as proteins. Here, we used NMR, CD, and ThT/fluorescence spectroscopy together with AFM imaging to study pH-dependent molecular interactions between single walled carbon nanotubes (SWNTs) and the amyloid-beta (A beta) peptide. The aggregation of the A beta peptide, first into oligomers and later into amyloid fibrils, is considered to be the toxic mechanism behind Alzheimer's disease. We found that SWNTs direct the A beta peptides to form a new class of beta-sheet-rich yet non-amyloid fibrils. Show less
Programmed ribosomal frameshifting (PRF) is one kind of recoding events that is mostly utilized by RNA viruses to synthesize more proteins with defined ratio from their compact genome and it is... Show moreProgrammed ribosomal frameshifting (PRF) is one kind of recoding events that is mostly utilized by RNA viruses to synthesize more proteins with defined ratio from their compact genome and it is known that the stoichiometric is critical to virus infection and propagation. Two cis-acting RNA elements are critical to induce PRF: one is slippery sequence where the frameshifting occurs and the other is RNA secondary structure, either a stem-loop or pseudoknot, to stall ribosomes on the slip site. In this thesis, we first demonstrate that a stem-loop structure can efficient replace pseudoknot in inducing frameshifting, arguing previous assumption hairpins are efficient frameshiftors. Furthermore, we show antisense oligonucleotides (AON) that mimic hairpin or pseudoknot can promote efficient frameshifting suggesting the downstream secondary structures act as physical barriers in frameshifting. Finally, we report a novel ligand responsive frameshifting signal derived from non-frameshifting preQ1 riboswitch aptamer. This interesting finding may have potential to select compounds with anti-bacteria ability. In sum, we successfully use in trans AONs or metabolites to induce PRF. These findings not only address fundamental mechanism of PRF but have potential to develop drugs against frameshifting diseases or bacteria. Show less
