Roles of the Dal82p domains in allophanate/oxalurate-dependent gene expression in Saccharomyces cerevisiae

Allophanate/oxalurate-induced gene expression in Saccharomyces cerevisiae r equires 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, UISALL. Dal82p consists of at least three do mains as follows: (i) UIS, DNA-binding, (ii) transcriptional activation, an d (iii) coil(DAL82). Here we show that the coiled-coil(DAL82) domain posses ses two demonstrable functions. (i) It prevents Dal82p-mediated transcripti on when inducer is absent. (ii) It is a major, although not exclusive, doma in through which the inducer signal is received. Supporting the latter conc lusion, a 38-amino acid fragment, containing little more than the coiled-co il(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), UISALL-binding domains. There may be an in teraction 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.