Abstract
Allophanate/oxalurate-induced gene expression in
Saccharomyces cerevisiae
requires at least five transcription factors, four of which act positively (Gln3p, Gat1p, Dal81p, and Dal82p) and one negatively (Dal80p). Gln3p binds to and Gat1p is proposed to bind to single GATA sequences; Dal80p binds to pairs of specifically oriented and spaced GATA sequences, and Dal82p binds to a pathway-specific element, UIS
ALL
. Dal82p consists of at least three domains as follows: (i) UIS
ALL
DNA-binding, (ii) transcriptional activation, and (iii) coiled-coil
DAL82
. Here we show that the coiled-coil
DAL82
domain possesses two demonstrable functions. (i) It prevents Dal82p-mediated transcription when inducer is absent. (ii) It is a major, although not exclusive, domain through which the inducer signal is received. Supporting the latter conclusion, a 38-amino acid fragment, containing little more than the coiled-coil
DAL82
domain, supports oxalurate-inducible, Dal81p-dependent, reporter gene transcription. Dal81p is required for inducer responsiveness of LexAp-Dal82p and LexAp coiled-coil
DAL82
-mediated transcription but isn’t needed for inducer-dependent activation mediated by a Dal82p containing deletions in both the coiled-coil
DAL82
, UIS
ALL
-binding domains. There may be an interaction between Dal81p and the coiled-coil
DAL82
domain since (i) Dal81p is required for transcription mediated by LexA-coiled-coil
DAL82
p and (ii) a Dal81p-Dal82p complex is detected by two-hybrid assay.