Cold shock response of yeast cells: induction of a 33 kDa protein and protection against freezing injury.

Cold shock (10 degrees C) treatment to Saccharomyces cerevisiae cells normally grown at 30 degrees C resulted in splitting of vacuoles and retarded membrane fluidity as detected by phase contrast microscopy and in vivo nuclear magnetic resonance (NMR) studies, respectively. The treatment was found to impart protection against subsequent freezing as studied by cell viability and colony forming efficiency. We have earlier reported similar protection and retarded membrane fluidity as a result of heat shock treatment to these cells (Obuchi et al., 1990). This suggests that cold shock and heat shock treatments to yeast cells evoke some analogous responses. However, biochemically a new 33 kDa protein (CSP 33) was detected upon cold shock treatment which is distinct from heat shock induced family of proteins (Kaul et al., 1992). We present here the first report of this kind and its practical implications for protection against freezing.