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Post by dulanjani on Oct 17, 2015 18:53:22 GMT -6
Potyvirus is a positive sense RNA virus which lacks 5' cap structure which is crucial for translation inetiation. Therefore these viruses use cap independent translation mechanism which uses VPg protein attached to the 5' end of the viral RNA. This VPg serves as an analogy of the 5' cap and plays a major role in mRNA translation by interacting with cap binding proteins such as elF4E and elFiso4F. This VPg also indirectly implicated in cell to cel movement of virus via plasmadesmata. This experiment was conducted using wheat germ and protein kinetic studies indicates that addition of VPg to wheat germ extract leads to enhancement of uncapped viral mRNA translation and inhibits the translation of capped viral mRNA. This VPg provides significant competitive advantage to the uncapped viral mRNA translation. Secondly to study interaction of VPg with cap binding proteins such as elF4E and elFiso4F viral RNA in wheat germ extract was used. Results indicates that both of these elF4E and elFiso4F proteins forms complex with VPg which makes 4 fold affinity to viral RNA than elF4E alone. Binding affinity of elF4E to viral RNA correlates with the translation efficiency. Having VPg interacting with elF4E increased elF4E binding yo viral RNA. Kinetic studies showed that elFiso4F with VPg show faster association than elF4E.VPg. This paper suggest a model where elF4E.VPg interaction enhanced the cap independent translation of the viral RNA. This model also applicable to all Eukaryotes which opens doors to understand interaction of initiation factors with mRNA translation in cells. Here is the paper i used potyvirus vpg.pdf (538.24 KB) |
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Post by gabriela on Oct 19, 2015 14:37:25 GMT -6
Potyvirus is a positive sense RNA virus which lacks 5' cap structure which is crucial for translation inetiation. Therefore these viruses use cap independent translation mechanism which uses VPg protein attached to the 5' end of the viral RNA. This VPg serves as an analogy of the 5' cap and plays a major role in mRNA translation by interacting with cap binding proteins such as elF4E and elFiso4F. This VPg also indirectly implicated in cell to cel movement of virus via plasmadesmata. This experiment was conducted using wheat germ and protein kinetic studies indicates that addition of VPg to wheat germ extract leads to enhancement of uncapped viral mRNA translation and inhibits the translation of capped viral mRNA. This VPg provides significant competitive advantage to the uncapped viral mRNA translation. Secondly to study interaction of VPg with cap binding proteins such as elF4E and elFiso4F viral RNA in wheat germ extract was used. Results indicates that both of these elF4E and elFiso4F proteins forms complex with VPg which makes 4 fold affinity to viral RNA than elF4E alone. Binding affinity of elF4E to viral RNA correlates with the translation efficiency. Having VPg interacting with elF4E increased elF4E binding yo viral RNA. Kinetic studies showed that elFiso4F with VPg show faster association than elF4E.VPg. This paper suggest a model where elF4E.VPg interaction enhanced the cap independent translation of the viral RNA. This model also applicable to all Eukaryotes which opens doors to understand interaction of initiation factors with mRNA translation in cells. Here is the paper i used Thanks so much for the info..  I have some questions: 1. Are elF4E and elFiso4F isoforms? like we reported in ssDNA or they are completely different initiator factors? 2. Has 4 fold affinity observed just with elFiso4F? |
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bea
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Post by bea on Oct 20, 2015 14:23:39 GMT -6
Tombusvirus is a genera that lacks 5’ capped or 3’polyadenilated in its genome. However, viruses in this genera, was found to contain a 3’- cap independent translational enhancer (3’CITE), as an example Tomato bushy stunt virus (TBSV). The 3’CITE is located in the 3’- untranslated region (3’UTR) of the virus’s genome which makes the translation of viral mRNAs in vivo easier. A RNA bridge between 5’-3’ RNA interaction mediates the delivery of translation-related factors bound to the 3’CITE to the 5’end of the message. The TBSV 3’CITE shows to be really functional when an assay in a plant protoplast is conducted, on the other hand in tests in vitro the TBSV 3’CITE was unable to activate translation. An experiment conducted with another Tombusvirus, Carnation Italian ringspot virus (CIRV) which contains a TBSV- like 3’CITE showed that it is active in wheat germ extract. Also it was demonstrate from the same experiment that the CIRV 3’CITE functions in vitro is similar to the TBSV 3’CITE in vivo. It has shown that the TBSV 3’CITE is able to enhance the translation in wheat germ extract if is present in short viral messages. The results from these experiments was possible to see the contrast of the possible activities of the TBSV-like 3’CITE either in vitro or in vivo.
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Post by dulanjani on Oct 21, 2015 14:03:43 GMT -6
Thanks so much for the info.. I have some questions: 1. Are elF4E and elFiso4F isoforms? like we reported in ssDNA or they are completely different initiator factors? 2. Has 4 fold affinity observed just with elFiso4F?Dear Gabby This is what I found you are correct on first question, eIF4F and elFiso4F are isozyme forms of eIF4F in higher plants. 4 fold affinity was shown when both of the elF4E and Vpg is together and formed a complex with compared to elF4E alone in the reaction. When the complex is formed with either initiation factor with Vpg it increase the affinity by 4 fold. Hope this was the answer you expected |
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Post by omararias on Oct 21, 2015 17:20:26 GMT -6
Potyvirus is a positive sense RNA virus which lacks 5' cap structure which is crucial for translation inetiation. Therefore these viruses use cap independent translation mechanism which uses VPg protein attached to the 5' end of the viral RNA. This VPg serves as an analogy of the 5' cap and plays a major role in mRNA translation by interacting with cap binding proteins such as elF4E and elFiso4F. This VPg also indirectly implicated in cell to cel movement of virus via plasmadesmata. This experiment was conducted using wheat germ and protein kinetic studies indicates that addition of VPg to wheat germ extract leads to enhancement of uncapped viral mRNA translation and inhibits the translation of capped viral mRNA. This VPg provides significant competitive advantage to the uncapped viral mRNA translation. Secondly to study interaction of VPg with cap binding proteins such as elF4E and elFiso4F viral RNA in wheat germ extract was used. Results indicates that both of these elF4E and elFiso4F proteins forms complex with VPg which makes 4 fold affinity to viral RNA than elF4E alone. Binding affinity of elF4E to viral RNA correlates with the translation efficiency. Having VPg interacting with elF4E increased elF4E binding yo viral RNA. Kinetic studies showed that elFiso4F with VPg show faster association than elF4E.VPg. This paper suggest a model where elF4E.VPg interaction enhanced the cap independent translation of the viral RNA. This model also applicable to all Eukaryotes which opens doors to understand interaction of initiation factors with mRNA translation in cells. Here is the paper i used Thank you so much for the information. Please I have some questions. 1. When the Vpg is competing for cap binding with eIF4F and eIFiso4F, how do you think that the abundance of the isoform factor and the realtive amount of its secondary structure will interfere or affect the translation rate of the host with comparing with eIF4F?. 2. Please could you describe briefly, how was the experimental design that was developed in order to obtain the kinetic measurements?. Thanks. |
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