Identification And Function Analysis Of The Target Protein Of BNP23, The HSP90 Co-chaperone Of Rapeseed

The special chaperone complex in mammalian, which was consisted of HSP 90, HSP 70 and its co-chaperone HSP 40, HOP (HSP 70 and HSP90 organizing protein) and p23, targeted on proteins such hormone receptors, transcription factors and several tyrosine kinases so on. The complex played a key role in signal transduction networks, cell-cycle control, protein degradation and protein trafficking. P23, as one co-chaperone of HSP90, could bind to HSP90 specially, let HSP90 bind or release the target protein by regulating the form of the HSP90 binding with ATP or ADP.Recently, there had been lots of studies on the function of P23 stabilizing the HSP90-target protein heterocomplex in mammalian, however, little was carried on in plants. The resistant disease protein RPM1 was the only one target protein of HSP90 that had been identified in Arabidopsis thaliana. In a functional complex reconstitution system in vitro, BNP23, which was heat-induced, and ATP23, which was constituted expressing, could both bind to HSP90 conversed as HsP23. However, they could not stabilize the HSP90 -Hormone receptor heterocomplex as HsP23, it was appeared that plant P23-like proteins didn't play a role in receptor-HSP90 heterocomplex assembly and they were more specific in their choice of hsp90 client complexs. To understand further the biological role of plant P23, we searched the interacted protein with BNP23 using Yeast two hybrids. The main results were the followings:1. Yeast two hybrids methods were used to screen the cDNA library of Arabidopsis thaliana seedling with BNP23 as the bait protein and the proteins interacted with BNP23 were isolated. There were thirty-nine cDNA sequence coding proteins which interacted with BNP23. Pyr10 binding protein 1(PBP1) was one of them.2. In vitro the interaction between BNP23 and PBP1 was ascertained by means of the protein-protein interaction and western blotting.3. The expression of PBP1 in deferent tissue of mature Arabidopsis thaliana plant was examined by RT-PCR. The result indicated that PBP1 was not expressed in stems, leaves and flowers, but specially expressed in root.4. The protein in Brassica napus homologous to PBP1 was found through amino acid sequence blast and the interaction with BNP23 was identified by Yeast two hybrids assay. The results indicated myrosase binding protein 6 (MBP6) in Brassica napus homologous to PBP1 was also interacted with BNP23.5. Jacalin, one conversed domain of MBP6 and PBP1, was identified to interact with BNP23. It was inferred that Jacalin was the interaction locus between myrosase...