Protein solubility and folding enhancement by interaction with RNA

While basic mechanisms of several major molecular chaperones are well understood, this machinery has been known to be involved in folding of only limited number of proteins inside the cells. Here, we report a chaperone type of protein folding facilitated by interaction with RNA. When an RNA-binding module is placed at the N-terminus of aggregation-prone target proteins, this module, upon binding with RNA, further promotes the solubility of passenger proteins, potentially leading to enhancement of proper protein folding. Studies on in vitro refolding in the presence of RNA, coexpression of RNA molecules in vivo and the mutants with impaired RNA binding ability suggests that RNA can exert chaperoning effect on their bound proteins. The results suggest that RNA binding could affect the overall kinetic network of protein folding pathway in favor of productive folding over off-pathway aggregation. In addition, the RNA binding-mediated solubility enhancement is extremely robust for increasing soluble yield of passenger proteins and could be usefully implemented for high-throughput protein expression for functional and structural genomic research initiatives. The RNA-mediated chaperone type presented here would give new insights into de novo folding in vivo.     

Enhancing biomass and fatty acid productivity of <Emphasis Type="Italic">Tetraselmis</Emphasis> sp. in bubble column photobioreactors by modifying light quality using light filters

Some artificial light sources able to emit photons at specific wavelengths, such as LEDs, are useful for studying the effects of light quality on microalgal growth and production of fatty acids; however, they should not be used for outdoor cultivation of microalgae to produce bioenergy. Instead, various light filters capable of selectively transmitting red, blue, and red+blue light regions in solar radiation were used to cover 0.4 L bubble column photobioreactors to cultivate Tetraselmis sp. KCTC12236BP and investigate the influence of light quality on microalgal growth and fatty acid production. Biomass and fatty acid productivities in red light (0.10 ± 0.05 g/L/day and 11.8 ± 0.5 mg/L/day, respectively) were 7 ~ 53% and 9 ~ 61% higher than other colored lights based on the same number of supplied photons, respectively. The composition of fatty acids did not change significantly in response to transmitted light qualities of the filter. The ratio of saturated to unsaturated fatty acids was 3:7, and their contents were 12% in all groups, which corresponds with the results of LEDs. Plotting biomass and fatty acid productivity over the red photon fraction in supplied light revealed that increased productivities were closely correlated with red photon fraction in the filtered light. Overall, the results presented herein indicate that enhanced production of algal fatty acid could be achieved by application of light filters in outdoor settings without artificial lights.     

Tripterygium regelii decreases the biosynthesis of triacylglycerol and cholesterol in HepG2 cells

In the course of screening to find a plant material decreasing the activity of triacylglycerol and cholesterol, we identified Tripterygium regelii (TR). The methanol extract of TR leaves (TR-LM) was shown to reduce the intracellular lipid contents consisting of triacylglycerol (TG) and cholesterol in HepG2 cells. TR-LM also downregulated the mRNA and protein expression of the lipogenic genes such as SREBP-1 and its target enzymes. Consequently, TR-LM reduced the TG biosynthesis in HepG2 cells. In addition, TR-LM decreased SREBP2 and its target enzyme HMG-CoA reductase, which is involved in cholesterol synthesis. In this study, we evaluated that TR-LM attenuated cellular lipid contents through the suppression of de novo TG and cholesterol biosynthesis in HepG2 cells. All these taken together, TR-LM could be beneficial in regulating lipid metabolism and useful preventing the hyperlipidemia and its complications, in that liver is a crucial tissue for the secretion of serum lipids.