Premium
On how a transcription factor can avoid its proteolytic activation in the absence of signal transduction
Author(s) -
Espeso Eduardo A.,
Roncal Tomás,
Díez Eliecer,
Rainbow Lynne,
Bignell Elaine,
Álvaro Josué,
Suárez Teresa,
Denison Steven H.,
Tilburn Joan,
Arst Herbert N.,
Peñalva Miguel A.
Publication year - 2000
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/19.4.719
Subject(s) - biology , signal transduction , transcription factor , microbiology and biotechnology , transcription (linguistics) , genetics , gene , linguistics , philosophy
In response to alkaline ambient pH, the Aspergillus nidulans PacC transcription factor mediating pH regulation of gene expression is activated by proteolytic removal of a negative‐acting C‐terminal domain. We demonstrate interactions involving the ∼150 C‐terminal PacC residues and two regions located immediately downstream of the DNA binding domain. Our data indicate two full‐length PacC conformations whose relative amounts depend upon ambient pH: one ‘open’ and accessible for processing, the other ‘closed’ and inaccessible. The location of essential determinants for proteolytic processing within the two more upstream interacting regions probably explains why the interactions prevent processing, whereas the direct involvement of the C‐terminal region in processing‐preventing interactions explains why C‐terminal truncating mutations result in alkalinity mimicry and pH‐independent processing. A mutant PacC deficient in pH signal response and consequent processing behaves as though locked in the ‘closed’ form. Single‐residue substitutions, obtained as mutations bypassing the need for pH signal transduction, identify crucial residues in each of the three interactive regions and overcome the processing deficiency in the ‘permanently closed’ mutant.