ABSTRACT
Objective To design and construct a new non-fusion soluble expression vector pTIG-mSUMO(small ubiq-uitin-related modifier) using the widely used solubility promoting protein SUMO and based on the translational coupling phenomenon in order to enable the non-fusion soluble expression of the broad-spectrum antiviral protein RA in Escherichia coli by pTIG-mSUMO.Methods The smt3 gene coding for SUMO protein was cloned from yeast genome DNA by PCR. After directed-site silent mutation to eliminate the EcoRⅠsite, the mutant mSUMO was inserted into pET-22b to obtain the translational coupling expression vector pTIG-mSUMO.The RA was subject to PCR amplification and cloned into the pTIG-mSUMO to obtain the expression plasmid pTIG-mSUMO/RA which was supposed to direct the soluble expression of RA by the translational coupling with mSUMO.Results A translational coupling expression vector pTIG-mSUMO which could di-rect/drive the SUMO and heterogonous protein non-fusion expression simultaneously was designed and constructed.The Western blotting result indicated that pTIG-mSUMO could direct the high-level expression of RA, around 40%of which was soluble.Conclusion A translational coupling expression vector pTIG-mSUMO is obtained.After coupling with SUMO, RA is highly expressed in E.coli and both the expression level and solubility are greatly improved.pTIG-mSUMO might contrib-ute to soluble expression of other proteins.
ABSTRACT
It′s reported that RNA-binding proteins ( RBP) play key roles in post-transcriptional regulation of eukaryotic genes.The aberrations of RBP are associated with a large number of human disorders , particularly autoimmune and neuro-logic diseases .The interaction between RNA and proteins has been widely explored since the development of the method known as RNA immunoprecipitation with differential display or microarray analysis (RIP-ChIP) around the year of 2000. Since then, diverse derivatives of the RIP-ChIP, such as ultraviolet crosslinking and immunoprecipitation ( CLIP), high-throughput sequencing of CLIP cDNA library (HITS-CLIP), photoactivatable -ribonucleoside-enhanced crosslinking and immunoprecipitation ( PAR-CLIP) , and individual nucleotide resolution CLIP ( iCLIP ) have been developed .All these methods have some advantages over the original RIP-ChIP and greatly facilitate the study of RBP-RNA interactions .Addi-tionally , aided by the next-generation sequencing , transcriptome-wide identification of RBP target sites has become possible and the RNA-binding site resolution of RBP has also improved to some degree .We introduced the basic principles and processes of the interactions between proteins and RNA , focusing on the advantages , disadvantages and prospect of the present genome-wide version of CLIP .
ABSTRACT
We reconstructed the erythromycin macrocyclic lactone (6-deoxyerythronolide B, 6dEB) synthesis pathway in Escherichia coli. We first cloned all the genes needed to synthesize the 6dEB into multi-gene co-expressed vectors. Then using the recognition sequences of isoschizomers Xba I/Spe I of vectors, we assembled the related genes into a series multiple-genes recombinant plasmids pBJ144, pBJ130. The recombinant plasmids pBJ144, pBJ130 were cotransformed into BAP1 to get the recombinant BAP1(pBJ144/pBJ130). SDS-PAGE analysis showed that individual genes were expressed correctly. After inducing at low temperature, adding propionate as substrate, we validated the crude product by mass spectrometry and the 6dEB yield was about 10 mg/L. These results indicated that the synthetic pathway of 6dEB was successfully assembled and reconstructed in Escherichia coli, which will greatly facilitate the reconstruction of whole erythromycin synthesis pathway and finally help to establish a stable research platform for developing of new derivatives of erythromycin and combinatorial biosynthesis of polyketide-type antibiotics.