Open AccessThe CbrB Regulon: Promoter dissection reveals novel insights into the CbrAB expression network in Pseudomonas putida
Author(s) -
Rocío Barroso,
Sofia Garcı́a-Mauriño,
Laura Tomás-Gallardo,
Eloísa Andújar,
Mónica Pérez-Alegre,
Eduardo Santero,
Inés Canosa
Publication year - 2018
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0209191
Subject(s) - regulon , rpon , operon , biology , regulation of gene expression , sigma factor , genetics , gene , pseudomonas putida , computational biology , orfs , promoter , microbiology and biotechnology , gene expression , open reading frame , mutant , peptide sequence
CbrAB is a high ranked global regulatory system exclusive of the Pseudomonads that responds to carbon limiting conditions. It has become necessary to define the particular regulon of CbrB and discriminate it from the downstream cascades through other regulatory components. We have performed in vivo binding analysis of CbrB in P . putida and determined that it directly controls the expression of at least 61 genes; 20% involved in regulatory functions, including the previously identified CrcZ and CrcY small regulatory RNAs. The remaining are porines or transporters (20%), metabolic enzymes (16%), activities related to protein translation (5%) and orfs of uncharacterised function (38%). Amongst the later, we have selected the operon PP2810-13 to make an exhaustive analysis of the CbrB binding sequences, together with those of crcZ and crcY . We describe the implication of three independent non-palindromic subsites with a variable spacing in three different targets; CrcZ, CrcY and operon PP2810-13 in the CbrAB activation. CbrB is a quite peculiar σ N —dependent activator since it is barely dependent on phosphorylation for transcriptional activation. With the depiction of the precise contacts of CbrB with the DNA, the analysis of the multimerisation status and its dependence on other factors such as RpoN o IHF, we propose a model of transcriptional activation.