Characterization of the interaction between E. coli FtsY and the SecYEG complex

Translocation of proteins into or across the lipid bilayer is an essential process for all living cells. The Sec translocon, known as Sec61αγβ in eukaryotes and SecYEG in prokaryotes, is composed of three subunits in which the largest one, Sec61α or SecY, constitutes the protein channel or pore in the membrane. For the majority of integral membrane proteins, translocation is performed through the signal recognition particle (SRP) pathway. In this pathway, the SRP recognizes and binds to the leading signal sequence of nascent proteins emerging from translating ribosomal units. Through an interaction with an SRP receptor (SR), located at the membrane, the SRP-ribosome-nascent chain complex is brought to close proximity of the Sec complex. In this thesis, the interaction between the prokaryotic SRP receptor, FtsY, and the SecYEG complex is analyzed. The A domain of FtsY is identified as the SecYEG-FtsY interacting domain by Blue Native PAGE and analytical gel filtration. Using surface plasmon resonance technique, the binding affinity of FtsY to the Sec translocon is measured. Finally, the interaction seems to inhibit the GTPase activity of FtsY.Medicine, Faculty ofBiochemistry and Molecular Biology, Department ofGraduat