Functional immobilization of a DNA-binding protein at a membrane interface via histidine tag and synthetic chelator lipids.

The coupling of a DNA-binding protein to self-organized lipid monolayers is examined at the air−water interface by means of film balance techniques and epifluorescence microscopy. We used two recombinant species of the heat shock factor HSF24 which differ only in a carboxy-terminal histidine tag that interacts specifically with the nickel-chelating head group of a synthetic chelator lipid. As key function, HSF24 binds to DNA that contains heat-shock responsible promoter elements. In solution, DNA−protein complex formation is demonstrated for the wild type and fusion protein. Substantial questions of these studies are whether protein function is affected after adsorption to lipid layers and whether a specific docking via histidine tag to the chelator lipid leads to functional immobilization. Using lipid mixtures that allow a lateral organization of chelator lipids within the lipid film, specific binding and unspecific adsorption can be distinguished by pattern formation of DNA−protein complexes. At the lip...