ISSN:
1573-4943
Schlagwort(e):
Acrylamide
;
fluorescence quenching
;
Tet repressor
;
H-t-H motif
;
protein-DNA binding
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Chemie und Pharmazie
Notizen:
Abstract A thorough investigation of the acrylamide fluorescence quenching of F75TetR, a mutant of the Tn10-encoded TetR repressor containing a single Trp residue at position 43, was carried out. The Trp-43 residue is located in a helixα-turn-helixα (H-t-H) motif involved in the specific binding of F75TetR to the operator site in specific DNA. Distinct Ranges of acrylamide concentration have been assumed. At acrylamide concentrations below 0.15–0.2 M (a usual range of values in fluorescence quenching studies) the observed limited tertiary structure change induced by acrylamide is consistent with a noncooperative local unfolding of the DNA-binding domain. It is suggested that penetration of the neutral quencher could cause the deletion of a hydrophobic tertiary structure contact, partly involving TrP-43, responsible for the anchoring of the H-t-H motif inside the three-helix protein bundle, characterizing the N-terminal part. Correspondingly, the affinity of the mutant repressor for the operator was shown to decrease substantially (about five orders of magnitude), seemingly losing its specificity. A subsequent phase, up to 0.8 M acrylamide, was observed in which the involved intermediate protein structure is not further perturbed, nor is DNA binding.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF01887401
Permalink
