Abstract
In bacteria and plants, Sec-, Tat- and SRP-pathway are known for protein translocation. SecA is essential component of in Sec-pathway. SecA operates to translocate preprotein into thylakoid lumen in plants. Primitive red alga Cyanidioschyzon merolae is unique in that secAgene exsists both in the nucleus and the plastid genome. The purpose of this study is to clarify the difference of two SecA. SecAs are investigated by the method of phylogenetic analysis, reverse transcript PCR, real time PCR and complementation test of Escherichia coli secA Ts mutant. The result showed that both secAs were transcripted. Phylogenetic analysis showed that secAin the nucleus was related to the mycobacterial secA2 which concerns auxiliary secretion factor in Sec pathway. Both of the two secA did not complement E.coli secA mutant. E.coli was rethal when plastid secA overexpressed while not nuclear secA. The results suggested that the two secAs have different function.
