DEVELOPMENTAL CONTROL OF THE HEAT-SHOCK STRESS REGULON IN STREPTOMYCES-COELICOLOR

In the differentiating eubacterium Streptomyces coelicolor, nutritiona l imbalances activate a developmental programme which involves the hea t-shock stress regulon. In liquid batch cultures, the growth curve cou ld be separated into four components: rapid growth 1 (RG1), transition (T), rapid growth 2 (RG2) and stationary (S). Patterns of gene expres sion in cultures subjected to heat shock in various phases were record ed on two-dimensional gels and analysed using advanced statistical met hods. The responses of all heat-shock proteins (HSPs) were highly depe ndent upon the growth phase, thus demonstrating that the four phases o f growth were physiologically distinct. For many HSPs, the levels of t hermal induction attained were closely related to growth stage-determi ned levels of synthesis before heat shock, thus supporting the idea th at developmental and thermal induction of this stress regulon have com mon control elements. Cluster analysis identified five groups of HSPs displaying similar kinetics of heat- and developmentally induced synth esis, probably reflecting the influence of major regulatory systems. M ethods introduced here to analyse the response of groups of genes to m ultiple simultaneous stimuli should find broad applications to studies of other prokaryotic and eukaryotic regulons.