Accumulation of glycine betaine in Synechococcus sp. PCC 7942 cells protects photosystem II from high-temperature induced inactivation

Abstract

Glycine betaine is a unique compatible osmolyte which protects the photosystem II (PSII) complex from a variety of stresses. Synechococcus sp. PCC 7942 cells transformed with the codA gene for choline oxidize from Arthrobacter globiformis has been shown to provide protection against photoinhibition at low temperature. Here we demonstrate that accumulation of glycine betaine in the transformed cells also protected the oxygen-evolving machinery of PSII from inactivation by elevated temperature. Temperature critical for the thermal inactivation of oxygen-evolving machinery of the transformed cells was approximately 7°C higher than that of the control cells. The transformed and the control cells grew at about same rate at 30°C and at 38°C, but between 40°C to 46°C the transformed cells grew faster than control cells that lacked the ability to accumulate glycine betaine. Thus accumulation of glycine betaine in vivo also seems to provide the transformed cells of ability to acclimate elevated temperature.