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.
Transcription of lysine genes in Saccharomyces cerevisiae is dependent on Lys14p and on alpha-aminoadipate semialdehyde (alphaAASA), 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 alphaAASA. 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 alphaAASA 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 alphaAASA-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 alphaAASA concentration.
El Alami
Mohamed
M
Laboratoire de Microbiologie, Faculté des Sciences, Université Libre de Bruxelles and Institut de Recherches Microbiologiques Jean-Marie Wiame, avenue E. Gryson 1, B-1070 Bruxelles, Belgium.
Feller
André
A
Piérard
André
A
Dubois
Evelyne
E
D015074:2-Aminoadipic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D003470:Culture Media; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D018841:HSP90 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D008239:Lysine / Q000378:metabolism*; D017354:Point Mutation; D017510:Protein Folding; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
D003470:Culture Media; D004268:DNA-Binding Proteins; C074510:HSP82 protein, S cerevisiae; D018841:HSP90 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C089506:LYS14 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D015074:2-Aminoadipic Acid; D008239:Lysine