The specific induction of genes in response to distinct environmental stress is 
vital for all eukaryotes. To study the mechanisms that result in selective gene 
responses, we examined the role of the fission yeast Tup1 family repressors in 
chromatin regulation. We found that chromatin structure around a cAMP-responsive 
element (CRE)-like sequence in ade6-M26 that is bound by Atf1.Pcr1 
transcriptional activation was altered in response to osmotic stress but not to 
heat and oxidative stresses. Such chromatin structure alteration occurred later 
than the Atf1 phosphorylation but correlated well with stress-induced 
transcriptional activation at ade6-M26. This chromatin structure alteration 
required components for the stress-activated protein kinase (SAPK) cascade and 
both subunits of the M26-binding CREB/ATF-type protein Atf1.Pcr1. Cation stress 
and glucose starvation selectively caused chromatin structure alteration around 
CRE-like sequences in cta3(+) and fbp1(+) promoters, respectively, in 
correlation with transcriptional activation. However, the tup11Delta tup12Delta 
double deletion mutants lost the selectivity of stress responses of chromatin 
structure and transcriptional regulation of cta3(+) and fbp1(+). These data 
indicate that the Tup1-like repressors regulate the chromatin structure to 
ensure the specificity of gene activation in response to particular stresses. 
Such a role for these proteins may serve as a paradigm for the regulation of 
stress response in higher eukaryotes.