Open AccessCatabolite Repression of the TodS/TodT Two-Component System and Effector-Dependent Transphosphorylation of TodT as the Basis for Toluene Dioxygenase Catabolic Pathway Control
Author(s) -
Andreas Büsch,
Jesús Lacal,
Hortencia Silva-Jiménez,
Tino Krell,
Juan L. Ramos
Publication year - 2010
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.00379-10
Subject(s) - biology , catabolite repression , operon , response regulator , biochemistry , effector , transcriptional regulation , transcription factor , transcription (linguistics) , regulon , microbiology and biotechnology , gene , mutant , linguistics , philosophy
The TodS/TodT two-component system ofPseudomonas putida regulates the expression of the toluene dioxygenase (tod ) operon for the metabolism of toluene, benzene, and ethylbenzene. The sensor kinase TodS has a complex domain arrangement containing two functional modules, each harboring a sensor and an autokinase domain separated by a receiver domain. The TodT protein is the cognate response regulator that activates transcription of the toluene dioxygenase (TOD) pathway genes at the PtodX promoter. We report in this study that thetodST operon is transcribed from a main promoter and that the +1 initiation point is located 31 nucleotides upstream from the A of the first ATG codon and is preceded by a −10/−35 canonical promoter. Expression from PtodS is under catabolite control, and in cells growing with glucose, the level of expression from this promoter is reduced, which in turn translates to low levels of the TodS/TodT regulators and results in a decrease of transcription from the PtodX promoter. Thus, the main underlying regulatory mechanisms of thetod structural genes are at the levels of catabolite repression control from PtodS and transcription activation, mediated by the TodT response regulator through a regulatory cascade in which the effector enhances autophosphorylation of TodS by ATP, with subsequent transphosphorylation of TodT.