Test of Interaction Between SRK and THL1 from Brassica oleracea L. in Self-Incompatibility Signaling Process

The S-locus receptor kinase (SRK) and thioredoxin-like protein 1 (THL1) from Brassica oleracea L. probably interact with each other in self-incompatibility signal process. To testify the interaction, the coding sequences of SRK kinase domain (termed SRKE1) and THL1 were amplified from stigma mRNA of B. oleracea. They were, then, inserted into the expression vector pET43.1a and yeast expression vector pPIC9K to construct the recombinant plasma pET43.1a-SRKE1, pPIC9K-SRKE1, and pET43.1a-THL1. The recombinant proteins were expressed in Escherichia coli (BL21) and Pichia pastoris (GS115), respectively. The recombinant THL1 was approved with oxidation/reduction activity by testing the ability of THL1 reducing insulin. Using a new method for testing the interaction between proteins, SRKE1 and THL1 were identified to combine with each other and form a stable complex.