Efficient production of RNA in Saccharomyces cerevisiae through inducing high level transcription of functional ncRNA-SRG1

RNA (Ribonucleic Acid) is an essential component of organisms and is widely used in the food and pharmaceutical industries. Saccharomyces cerevisiae, recognized as a safe strain, is widely used for RNA production. In this study, the S. cerevisiae W303-1a was used as a starting strain and molecular modifications were made to the functional ncRNA-SRG1 to evaluate the effect on RNA production. At the same time, its transcriptionally associated helper genes (Spt2, Spt6 and Cha4) were overexpressed and the culture medium was supplemented with serine to induce SRG1 transcription, to increase SRG1 transcription levels and investigate its effect on intracellular RNA levels. The results showed that the intracellular RNA content of the recombinant strain W303-1a-SRG1 was 10.27 %, an increase of 11.15 % compared to the starting strain (W303-1a, with an intracellular RNA content of 9.24 %). On this basis, a gene co-overexpression strain-W303-1a-SRG1-Spt6 was constructed. Simultaneously, the addition of 2 % serine strategy was used to increase the transcription level of SRG1 and RNA content of the recombinant strain. The intracellular RNA of the recombinant strain reached 11.41 %, an increase of 23.38 % compared to the starting strain (W303-1a, without serine supplementation). In addition, the growth performance of the strain was assessed by measuring the SRG1 transcription level in the strain and plotting the growth curve. Therefore, we found that improving the transcription level of ncRNA can be used as a new idea to construct S. cerevisiae with high RNA content, which provides a strong help for subsequent research in related fields. This work provides a new strategy for increasing the nucleic acid content of S. cerevisiae.

A photoactivatable Ru (II) complex bearing 2,9-diphenyl-1,10-phenanthroline: A potent chemotherapeutic drug inducing apoptosis in triple negative human breast adenocarcinoma cells

The photoactivatable Ru (II) complex 1 [Ru(bipy)2(dpphen)]Cl2 (where bipy = 2,2'-bipyridine and dpphen = 2,9-diphenyl-1,10-phenanthroline) has been shown to possess promising anticancer activity against triple negative adenocarcinoma MDA-MB-231 cells. The present study aims to elucidate the plausible mechanism of action of the photoactivatable complex 1 against MDA-MB-231 cells. Upon photoactivation, complex 1 exhibited time-dependent cytotoxic activity with a phototoxicity index (P Index) of >100 after 72 h. A significant increase in cell rounding and detachment, loss of membrane integrity, ROS accumulation and DNA damage was observed. Flow cytometry and a fluorescent apoptosis/necrosis assay showed an induction of cell apoptosis. Western blot analysis revealed the induction of intrinsic and extrinsic pathways and inhibition of the MAPK and PI3K pathways. The photoproduct of complex 1 showed similar effects on key apoptotic protein expression confirming that it is behind the observed cell death. In conclusion, the present study revealed that complex 1 is a potent multi-mechanistic photoactivatable chemotherapeutic drug that may serve as a potential lead molecule for targeted cancer chemotherapy.

XC_0531 encodes a c-type cytochrome biogenesis protein and is required for pathogenesis in Xanthomonas campestris pv. campestris

Background

The phytopathogenic Xanthomonas campestris pv.campestris is a gram-negative bacterium and the causal agent of black-rot disease of cruciferous crops. Many gram-negative bacteria possess a family of proteins, called Dsbs, which are involved in disulfide bond formation in certain periplasmic proteins. In our preliminary screening of the virulence to the plants we identified that gene XC_0531 which annotated gene dsbD of Xanthomonas campestris pv. campestris (Xcc) is related to the virulence to the host plants.

Results

Here, we found XC_0531 encoded a DsbD like protein. Its deletion is sensitive to DTT and copper, decreased accumulation of free thiols in periplasm. Its deletion also affected heme synthesis, position of Soret band and the production of peak c550. This suggests that XC_0531 is related to c-type cytochromes biogenesis. XC_0531 mutation decreased the utilization of different carbon sources (such as galactose, xylose, maltose, saccharose and glucose), reduced extracellular polysaccharide (EPS) production, decreased extracellular enzyme activities (protease, cellulose and amylase), slowed down growth rate of Xcc and weakened virulence to the plants. These results suggest that these phenotypes caused by XC_0531 mutation is possibly due to deficient biosynthesis of c-type cytochromes in respiration chain and the formation of disulfide bonds. Our work confirmed the function of XC_0531 and provide theory basis for scientists working on molecular mechanisms of cytochrome c biogenesis, pathogenesis of Xcc, development of EPS commercial values and protecting plant from black rot.

Conclusion

We confirmed the function of gene XC_0531, which encodes a DsbD like protein, a protein correlated with c-type cytochrome biogenesis. This gene is related to the virulence to plants by affecting funtion of cytochromes c and probably disulfide bonds modification of proteins in type II secretion system (T2SS).

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-017-1056-9) contains supplementary material, which is available to authorized users.

The yeast BDF1 regulates endocytosis via LSP1 under salt stress

Bromodomain-containing transcription factor, a kind of important regulating protein, can recognize and bind to acetylated histone. The homologous genes, BDF1 and BDF2, in Saccharomyces cerevisiae, respectively, encode a bromodomain-containing transcription factor. Previously study has demonstrated that both BDF1 and BDF2 participate in yeast salt stress response. Bdf1p deletion cells are sensitive to salt stress and this phenotype is suppressed by its homologue BDF2 in a dosage-dependent manner. In this study, we show that the histone deacetylase SIR2 over-expression enhanced dosage-dependent compensation of BDF2. SIR2 over-expression induced a global transcription change, and 1959 gene was down-regulated. We deleted some of the most significant down-regulated genes and did the spot assay. The results revealed that LSP1, an upstream component of endocytosis pathway, and CIN5, a transcription factor that mediates cellular resistance to stresses, can enhance salt resistance of bdf1∆. Further analysis demonstrated that under salt stress the endocytosis is over-activated in bdf1∆ but was recovered in bdf1∆ lsp1∆. To our best knowledge, this is the first report that the transcription factor Bdf1p regulates endocytosis under salt stress via LSP1, a major component of eisosomes that regulate the sites of endocytosis.