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The proper folding of a long C‐terminal segment of the yeast Lys14p regulator is required for activation of LYS genes in response to the metabolic effector
Author(s) -
Alami Mohamed El,
Feller André,
Piérard André,
Dubois Evelyne
Publication year - 2002
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2002.02854.x
Subject(s) - biology , effector , gene , saccharomyces cerevisiae , transcription (linguistics) , microbiology and biotechnology , activator (genetics) , transcription factor , repressor lexa , dna , genetics , repressor , linguistics , philosophy
Summary Transcription of lysine genes in Saccharomyces cerevisiae is dependent on Lys14p and on α ‐aminoadipate semialdehyde ( α AASA), an intermediate of the pathway. The two‐thirds C‐terminal end of Lys14p is sufficient to ensure the activation function of the protein and its modulation by α AASA. Here, we show that no single discrete domain of Lys14p is able to activate transcription and that most of the deleted LexA–Lys14p proteins are inactive even in the presence of a high α AASA concentration. The point mutations abolishing the activation capacity of Lys14p are distributed all over the entire C‐terminal segment. Although the deletion of 20 residues rich in leucine and located downstream of the DNA‐binding domain converts Lys14p to a constitutive transcriptional activator, our analysis provides evidence that the modulation process of Lys14p activity does not involve an effector‐dependent masking/unmasking mechanism. Furthermore, we show that the protein chaperone Hsp82p is required for full activation of LYS genes by the α AASA‐activated Lys14p as well as by the constitutive Lys14p. Our results suggest that the proper folding of the two‐thirds C‐terminal portion of Lys14p is essential not only to activate transcription but also to modulate it according to α AASA concentration.