English   español  
Please use this identifier to cite or link to this item: http://hdl.handle.net/10261/13110
Share/Impact:
Statistics
logo share SHARE logo core CORE   Add this article to your Mendeley library MendeleyBASE

Visualizar otros formatos: MARC | Dublin Core | RDF | ORE | MODS | METS | DIDL | DATACITE
Exportar a otros formatos:

Title

Optimization of the palindromic order of the TtgR operator enhances binding cooperativity

AuthorsKrell, Tino; Terán, Wilson; López Mayorga, Obdulio; Rivas, Germán ; Jiménez, Mercedes ; Daniels, Craig; Molina Henares, Antonio Jesús; Martínez-Bueno, Manuel; Gallegos, María Trinidad ; Ramos, Juan L.
KeywordsRepressor
Pseudomonas
Transcriptional regulation
TetR family
Analytical ultracentrifugation
Issue Date22-Jun-2007
PublisherElsevier
CitationJournal of Molecular Biology (2007) 369, 1188–1199
AbstractTtgR is the specific transcriptional repressor of the TtgABC efflux pump. TtgR and the TtgB efflux pump proteins possess multidrug-binding capacity, and their concerted action is responsible for the multidrug resistance phenotype of Pseudomonas putida DOT-T1E. TtgR binds to a pseudo-palindromic site that overlaps the ttgR/ttgA promoters. Dimethylsulfate footprint assays reveal a close interaction between TtgR and the central region of this operator. The results of analytical ultracentrifugation demonstrate that TtgR forms stable dimers in solution, and that two dimers bind to the operator. Microcalorimetric analysis of the binding of the two TtgR dimers to the cognate operator showed biphasic behavior, and an interaction model was developed for the cooperative binding of two TtgR dimers to their target operators. The binding of the two TtgR dimers to the operator was characterized by a Hill coefficient of 1.63 ± 0.13 (kD = 18.2( ± 6.3) μM, kD′ = 0.91( ± 0.49) μM), indicating positive cooperativity. These data are in close agreement with the results of sedimentation equilibrium studies of TtgR–DNA complexes. A series of oligonucleotides were generated in which the imperfect palindrome of the TtgR operator was empirically optimized. Optimization of the palindrome did not significantly alter the binding of the initial TtgR dimer to the operator, but increased the cooperativity of binding and consequently the overall affinity. The minimal fragment for TtgR binding was a 30-mer DNA duplex, and analysis of its sequence revealed two partially overlapping inverted repeats co-existing within the large pseudo-palindrome operator. Based on the architecture of the operator, the thermodynamics of the process, and the TtgR–operator interactions we propose a model for the binding of TtgR to its target sequence.
Publisher version (URL)http://dx.doi.org/10.1016/j.jmb.2007.04.025
URIhttp://hdl.handle.net/10261/13110
DOIhttp://dx.doi.org/10.1016/j.jmb.2007.04.025
ISSN0022-2836
Appears in Collections:(EEZ) Artículos
(CIB) Artículos
Files in This Item:
There are no files associated with this item.
Show full item record
Review this work
 

Related articles:


WARNING: Items in Digital.CSIC are protected by copyright, with all rights reserved, unless otherwise indicated.