Translational control plays an important role in the adaptive heat-shock response of Streptomyces coelicolor

Stress-induced adaptations require multiple levels of regulation in all organisms to repair cellular damage. In the present study we evaluated the genome-wide transcriptional and translational changes following heat stress exposure in the soil-dwelling model acti- nomycete bacterium, Streptomyces coelicolor. The combined analysis revealed an unprecedented level of translational control of gene expression, deduced through polysome profiling, in addition to transcrip- tional changes. Our data show little correlation be- tween the transcriptome and ‘translatome’; while an obvious downward trend in genome wide transcrip- tion was observed, polysome associated transcripts following heat-shock showed an opposite upward trend. A handful of key protein players, including the major molecular chaperones and proteases were highly induced at both the transcriptional and trans- lational level following heat-shock, a phenomenon known as ‘potentiation’. Many other transcripts en- coding cold-shock proteins, ABC-transporter sys- tems, multiple transcription factors were more highly polysome-associated following heat stress; interest- ingly, these protein families were not induced at the transcriptional level and therefore were not previ- ously identified as part of the stress response. Thus, stress coping mechanisms at the level of gene ex- pression in this bacterium go well beyond the induc- tion of a relatively small number of molecular chap- erones and proteases in order to ensure cellular sur-vival at non-physiological temperatures.