ABSTRACT
Background: Transgenic plants inhabiting single Bt gene are prone to develop insect resistance and this resistance has been reported in case of some important yield-devastating insect larvae of commercial crops, such as cotton and rice. Therefore, it has become essential to adapt new strategies to overcome the problem of insect resistance and these new strategies should be sophisticated enough to target such resistant larvae in broad spectrum. Among these, plants may be transformed with Bt gene tagged with some fusion-protein gene that possesses lectin-binding capability to boost the binding sites for crystal protein gene within insect mid-gut in order to overcome any chances of insect tolerance against Bt toxin. Enhanced chloroplast-targeted Bt gene expression can also help in the reduction of insect resistance. Results: In the present investigation, a combined effect of both these strategies was successfully used in cotton (G. hirsutum). For this purpose, plant expression vector pKian-1 was created, after a series of cloning steps, carrying Cry1Ac gene ligated with chloroplast transit peptide towards N-terminal and Ricin B-Chain towards C-terminal, generating TP-Cry1Ac-RB construct. Conclusions: Efficacy of pKian-1 plasmid vector was confirmed by in-planta Agrobacterium-mediated leaf GUS assay in tobacco. Cotton (G. hirsutum) local variety MNH-786 was transformed with pKian-1 and the stable integration of TP-Cry1Ac-RB construct in putative transgenic plants was confirmed by PCR; while fusion-protein expression in cytosol as well as chloroplast was substantiated by Western blot analysis. Whereas, confocal microscopy of leaf-sections of transgenic plants exposed that hybrid-Bt protein was expressing inside chloroplasts.
Subject(s)
Chloroplasts/genetics , Chloroplasts/metabolism , Plants, Genetically Modified , Chloroplast Proteins/isolation & purification , Ricin/analysis , Protein Sorting Signals , Blotting, Western , Cloning, Molecular , Microscopy, Confocal , Agrobacterium , Chloroplast Proteins/genetics , InsectaABSTRACT
Objective To determine the functional motif of the recombinant Ricin B(rRicin B) in Vibrio vulnificus cytolysin (VVC) and understand its molecule pathogenic mechanism.Methods The motif of VVC was predicted through bioinformatics analysis and cloned into a procaryotic expression vector pET28a-rRicin B.The recombinant plasmid was transformed into E.coli BL21 (DE3) and induced by IPTG to express rRicin B.The expressed protein was further analyzed by SDS-PAGE and purified by Ni2+-NTA agarose.Renaturation of the rRicin B were also carried out for further analysis.ELISA assay and confocal microscope was applied to identify the activity of the rRicin B on human Hela cells.Results Ricin B motif located in the 336-465 amino acids of Vibrio vulnificus cytolysin with a relative molecular weight of 20×103.The result of ELISA showed that the antigenicity of rRicin B was 28.71 U/L after renaturation.FITC labeled rRicin B could bind to the cell membrane and enter the cytoplasm of human Hela cells.Conclusion The Ricin B motif in Vibrio vulnificus cytolysin bearing the similar ability with the natural Ricin B can bind to the cell membrane and enter the cytoplasm.This feature may play an important role in the activity of pore-forming and the cytotoxicity of Vibrio vulnificus cytolysin.
ABSTRACT
Multiple forms of ricin have been isolated from castor bean seeds. Two forms, ricin-1 and ricin-2, differ in their isoelectric pI values and toxicity towards IMR- 32 cells. Inhibition of IMR-32 DNA polymerase α2 is more pronounced with ricin-1 (65%) than with ricin-2 (10%). Ricin Β chain (pI = 5.2) isolated from ricin-1 binds to IMR-32 cell surfaces as well as inhibits DNA polymerase α2 activity when studied in vitro. The presence of galβ-linked glycoconjugates near the active site of IMR-32 DNA polymerase α2 has been proposed. Replication modulators which bind to the glycose portion of the enzymes involved in the replication system may need a mandatory binding to cell surface glycoconjugates for their activity.