PHOSPHORYLATION OF MEMBRANE-PROTEINS IN RESPONSE TO TEMPERATURE IN ANANTARCTIC PSEUDOMONAS-SYRINGAE

Temperature-dependent phosphorylation and dephosphorylation of membran e proteins was studied in vitro in a number of psychrotrophic Antarcti c bacteria which grow between 0 and 30 degrees C. One of them, a Pseud omonas syringae isolate, was studied in detail and was found to have t hree membrane proteins of molecular mass 30, 65 and 85 kDa which were phosphorylated differently in response to low and high temperatures. T he 65 kDa protein was phosphorylated only at lower temperatures (betwe en 0 and 15 degrees C). The 30 kDa protein was phosphorylated more at higher temperatures and was possibly a histidine kinase. This protein was present in all the psychrotrophic Pseudomonas species studied and in Sphingobacterium antarcticus. A possible role for these proteins in sensing environmental temperature is proposed.