Does GB Stabilize Complex Proteins and Membranes in Vivo?
The protective effects of GB on macromolecules, such as complex proteins and membranes, which have been well demonstrated in vitro, are clearly recognizable in vivo also. Under various stress conditions, GB protects the PSII complex from photo-induced inactivation in transgenic cells of Synechococcus and in plants (Table II). The protection by GB of the photosynthetic machinery against photo-induced damage can be attributed to acceleration of the recovery of the PSII complex from such damage (Deshnium et al., 1997; Alia et al., 1999; Holmström et al., 2000). Evidence that membranes are targets of the action of GB in vivo has been obtained from Synechococcus cells that have been transformed with the codA gene (Deshnium et al., 1997). In the transgenic strain, there is a downward shift in the temperature at which the transition from the liquid-crystalline state to the phase-separated state occurs in the lipid phase of the plasma membrane. The lowering of the temperature of the phase tran