Thylakoid Transit Peptide Is Related to the Expression and Localization of NdhB Subunits in Soybean

The chloroplast NAD(P)H dehydrogenase (NDH) complex, as one of the most important photosynthesis protein complexes in thylakoid membrane, is involved in photosystem I (PSI) cyclic electron transport (CEF). Under abiotic environmental stress, the photosynthetic apparatus is susceptible to the damage caused by the strong light illumination. However, the enhancement of NDH-dependent CEF could facilitate the alleviation of the damage to the photosynthetic apparatus. The NdhB subunit encoded by chloroplast genome is one of most important subunits of NDH complex and consists of 510 amino acids. Here, according to cloning ndhB from Melrose (cultivated soybean), ACC547 (wild salt-tolerant soybean), S113-6 and S111-9 (hybrid descendant), based on the comparison and analysis of the sequences of NdhB subunits, we found that there is a novel thylakoid transit peptide of NdhB subunit in S111-9. In addition, crosslink immunoprecipitation, immunogold labeling and co-expression of GFP fusion protein indicated that the novel thylakoid transit peptide is favorable to the expression and localization of NdhB subunit in chloroplast. Therefore, we suggest that this novel thylakoid transit peptide plays the same role as chaperonin and contributes to facilitating the expression and localization of NdhB subunit.