Nucleotide and negatively charged lipid‐dependent vesicle aggregation caused by SecA

FEBS Letters

Breukink, Eefjan¹  Kruijff, Ben de¹  Keller, Rob C.A.¹ 

[1] Department of Biochemistry of Membranes of the Centre for Biomembranes and Lipid Enzymology, 3584 CH Utrecht, The Netherlands

关键词: Protein translocation;    SecA;    Vesicle aggregation;    Model membrane;    Lipid packing;    pmsf;    phenylmethylsulfonylfluoride;    LUV;    large unilamellar vesicle;    DPH;    1;    6-diphenyl-1;    3;    5-hexatriene;    DOPG;    1;    2-di-oleoyl-sn-glycero-3-phosphoglycerol;    DOPC;    1;    2-dioleoyl-sn-glycero-3-phosphocholine;   

DOI  :  10.1016/0014-5793(93)80289-7

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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.

【 授权许可】

Unknown