Abstract
SecA which is an overall acidic protein was found to induce an increase in the turbidity of a solution of vesicles consisting of negatively charged phospholipids. This increase was found to be due to an aggregation of the vesicles mediated by SecA. The SecA-mediated vesicle aggregation was not found for zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphocholine and showed a large dependence on both temperature and ionic strength. Furthermore it was shown that ATP and to a lesser extent ADP+P(i) were able to reduce the SecA-mediated vesicle aggregation, while no effect could be seen for a non-hydrolysable ATP analog AMP-PNP. Using the steady state fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene present in 1,2-dioleoyl-sn-glycero-3-phosphoglycerol vesicles we could show that SecA inserts in the bilayer. Monolayer studies confirmed that SecA is able to cause close contact between two membranes and gave a direct insight into the different types of lipid-protein interactions involved. From our results we propose that the SecA monomer possesses two lipid-binding sites which in the functional dimer conformation are responsible for the SecA-mediated vesicle aggregation.
Original language | English |
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Pages (from-to) | 19-24 |
Number of pages | 6 |
Journal | FEBS Letters |
Volume | 331 |
Issue number | 1-2 |
DOIs | |
Publication status | Published - 9 Jan 1993 |
Keywords
- lipid packing
- model membrane
- protein translocation
- secA
- vesicle aggregation
- protein SecA
- unclassified drug
- article
- binding site
- Escherichia coli
- ligand binding
- nonhuman
- phospholipid vesicle
- priority journal
- protein transport