Functional relationship among TATA sequences, gene induction and transcription initiation in the β-galactosidase, LAC4, gene from Kluyveromyces lactis

Summary

In the 5′ non-coding region of the β-galactosidase, LAC4, gene of Kluyveromyces lactis, three TATA-like sequences are present at −230, −170 and −142 from the ATG translation start site. By means of deletion mutations in the TATA region, at least two of these TATA sequences, those at −230 and −142, were shown to be required for normal gene expression. Evidence is presented for a functional hierarchy and cooperation between these TATA sequences. The deletion or a change in the position of the TATA sequences affects both β-galactosidase induction and the location of RNA initiation sites. The TATA sequence at −230 alone is sufficient for correct gene induction when it is moved to a position 41 by from the major RNA initiation sites located around −110; the −142 TATA alone contributes only partly to gene induction. We suggest a functional distinction between these two related regulatory sequences. This functional distinction might be established by sequence differences and/or targets of unlike specific DNA binding protein(s). A conformational analysis of the LAC4 promoter showed that under torsional stress the functional elements UAS, TATA boxes RNA initiation sites and ATG can be detected as Pl-sensitive sites. Possible functions of DNA structural alterations on gene expression are discussed.