Transcriptional and post-translational regulation of neutral trehalase in Schizosaccharomyces pombe during thermal stress

In the fission yeast Schizosaccharomyces pombe, a heat shock enhances transcription of the ntp1(+) gene, encoding the hydrolytic enzyme neutral trehalase. As compared to wild-type cells, cells devoid of the MAP kinase Sty1p showed a strong decrease in ntpl(+) expression induced by the temperature upshift, indicating that the stress-activated protein kinase (SAPK) pathway regulates the expression of this gene during heat shock. The transcription factor Atf1p, which is the main downstream target for Sty1p in the SAPK pathway, appears to be involved in such control, since ntpl(+) expression under heat shock proved to be significantly blocked in atf1(+)-disrupted cells. Serial deletion and point mutation analyses of the ntpl(+) promoter, as well as electrophoretic mobility shift assays, revealed the existence of a CRE-like element as the target for Atf1p-mediated expression under thermal stress. The relevance of two putative HSE elements located in the ntpl(+) promoter was also investigated for their potential role in regulating ntpl(+) transcription during heat shock. The results support a model in which heat-induced Atf1p binding to the CRE-like element favours the subsequent interaction of the heat shock factor (HSF) with HSE elements in the ntpl(+) promoter. Unlike what happens under osmostress or oxidative treatments, Sty1p has no role in the post-translational activation of neutral trehalase induced by heat shock in the fission yeast. Copyright (C) 2004 John Wiley Sons, Ltd.