Identification And Function Analysis Of The Interactive Proteins Of BAK1

Brassinosteroids associated receptors BAK1(BRI1-Associated Receptor Kinase), interacted with BRI1 to regulate the BRs perception and transduction. In recent years, many BAK1 interacted proteins have been found, which regulate a series of biological process, such as PAMP triggered immunity(PTI), programmed cell death(PCD) and development. This study also found a new BAK1 interaction protein K27, which was proved in vivo and in vitro. Throgh overexpression of K27 in Arabidopsis, we found it participated in plant growth and development.Main results in this study:1. Using BiFC technology, demonstrated that K27 and its homologous proteins K20 interacted with BAK1 on cytomembrane in vivo.2. Constructed the fusion expressed vector Cam-35S-K27-GFP, and overexpressed K27 gene in wild type Arabidopsis Col-0. The transgenic plants showed dwarf, diminished rosette leaves, leaves became round and small, increased leaf numbers, decreased fertility and a part of inflorescences death early. When overexpressed K27 gene in bak1-4(a mutant of BAK1), the transgenic plant also performed the morphology in Col:K27, and the phenomenon was more serious. Based on this results, we daringly speculated that BAK1 restricted K27 functions in plants.3. Observing the K27 was located on cell membrane and cytoplasm, it has the same function area with BAK1 and itself special function areas.4. This study demonstrated that BAK1 interacted with K27 in vivo. Using RT-PCR tested that when plant knock out BAK1 gene that increased expression of K27 gene quantity, and at the same time, the expression level of ethylene signal response gene PDF1.2 also increased. So, we concluded that BRs signal transduction had the potential crosstalk with ethylene signal, and we maybe find the key point component in it. Also, our results need more evidences on molecular biology and physiological biochemical tests to support.5. The bioinformatics methods were used to analyze the genetic relationships of K27 homologous proteins among Brassica rapa, Lycopersicon esculentum and Cucumis sativus. Phylogenetic tree analysis and Motif search results revealed that the homologous proteins were conservative and could be divided into two subclasses. Prediction of protein subcellular locations showed that K27 homologous proteins from these three kinds of vegetables were distribution on the cell membranes and most of the organelles’ membranes except for golgi apparatus.6. The genetic transformation system of Lycopersicon esculentum were preliminary established, using Micro-Tom the model plant and MA42 a weak BRI1 allele mutant as materials.