Characterization of the Alterations in the Thylakoid Pigment Proteins Under Cold Stress in the Intact Cells of the Cyanobacterium; Spirulina Platensis

The response of Spirulina platensis to cold stress (10°C) for 12h was investigated by incubating the intact cells in light of moderate intensity. It inhibits energy transfer from phycocyanin to chlorophyll a and specifically affecting the anchor and linker polypeptides, in cyanobacterium. Cold treatment of intact cells also resulted in the alteration of other thylakoid membrane proteins: most prominently, a dramatic diminishment of 37.2-kDa and 97.1 kDa proteins, and appearance of a new polypeptide around 47kDa were observed in SDS-PAGE. The SDS Gel of PBsomes isolated from cold stressed samples exhibited the loss in the content of linker polypeptides in the range of 32-37kDa particularly degradation of 35kDa which links PC to APC. Therefore we conclude that cold stress for long term has various effects on photosynthetic electron transport activities due to marked alterations in the composition of thylakoid membrane proteins.