Stress or heat shock protein synthesis and cellular filamentation in psychrophilic and psychrotrophic bacteria

Abstract

The response of an arctic psychrophile Aquaspirillum sp. Res-10 and the psychrotroph Bacillus psychrophilus to heat shock and nalidixic acid was investigated. Both agents induced heat shock proteins (hsps) or stress proteins and cellular filamentation in these bacteria. With Aquaspirillum sp. Res-10, nalidixic acid added to cells at 0° C induced the synthesis of 9 stress proteins, 3 of which were similar to hsps induced during a 0 to 20° C heat shock. Treatment of B. psychrophilus with nalidixic acid at 20° C resulted in induction of 12 stress proteins, 4 of which were similar to hsps produced during heat shock from 20 to 32° C. Using the dnaK gene of Escherichia coli (the equivalent of the major hsp 70 gene found in many organisms) as a radiolabeled probe, it was found that both the psychrophile and the psychrotroph possessed genomic sequences which were homologous to this gene. In addition, this same radiolabeled probe was used to detect the induction of homologous mRNA transcripts in Aquaspirillum sp. Res-10.