This chapter discusses the identification and reconstitution of anion exchange mechanisms in bacteria. Work with vesicles and proteoliposomes shows that the chemiosmotic transport of sugar phosphates occurs, not by proton-symport, but by anion exchange, in both gram-positive and gram-negative bacteria. Further analysis shows the existence of a variable stoichiometry that allows homologous sugar phosphate exchange to mediate an unexpected net uptake of substrate. Because this exchange causes the influx of protons along with the sugar phosphate, continued transport depends on maintenance of a pH gradient (alkaline inside), thereby ensuring that the Pi-linked exchangers take part in the overall chemiosmotic circuitry of the cell. The study of Pi-linked exchange has defined not only their physiological and biochemical properties, but has also been the vehicle for development of a particularly simple set of protocols designed to study such proteins in an artificial liposomal system. Such methods that take advantage of the stabilizing effects of osmolytes (e.g., glycerol), have made it possible to use reconstitution in an analytical fashion, not just as a preparative tool.
|Original language||English (US)|
|Number of pages||24|
|Journal||Advances in Cellular and Molecular Biology of Membranes and Organelles|
|State||Published - Jan 1 1995|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology