A U-Box Type E3 Ubiquitin Ligase Prp19-Like Protein Negatively Regulates Lipid Accumulation and Cell Size in

Microalgae lipid triacylglycerol is considered as a promising feedstock for national production of biofuels. A hotspot issue in the biodiesel study is to increase TAG content and productivity of microalgae. Precursor RNA processing protein (Prp19), which is the core component of eukaryotic RNA splice NTC (nineteen associated complex), plays important roles in the mRNA maturation process in eukaryotic cells, has a variety of functions in cell development, and is even directly involved in the biosynthesis of oil bodies in mouse. Nevertheless, its function in remains unknown. Here, transcriptional level of under nutrition deprivation was analyzed, and both its RNA interference and overexpressed transformants were constructed. The expression level of was suppressed by nitrogen or sulfur deficiency. Cell densities of RNAi lines decreased, and their neutral lipid contents increased 1.33 and 1.34 times over those of controls. The cells of RNAi lines were larger and more resistant to sodium acetate than control. Considerably none of the alterations in growth or neutral lipid contents was found in the overexpression transformants than wild type. Fatty acids were also significantly increased in RNAi transformants. Subcellular localization and yeast two-hybrid analysis showed that CrPrp19 was a nuclear protein, which might be involved in cell cycle regulation. In conclusion, CrPrp19 protein was necessary for negatively regulating lipid enrichment and cell size, but not stimulatory for lipid storage.