Curation Information

Publication: Elaborate transcription regulation of the Bacillus subtilis ilv-leu operon involved in the biosynthesis of branched-chain amino acids through global regulators of CcpA, CodY and TnrA.;Tojo S, Satomura T, Morisaki K, Deutscher J, Hirooka K, Fujita Y;Molecular microbiology 2005 Jun; 56(6):1560-73 [15916606]
TF: CcpA [P25144, view regulon]
Reported TF sp.: Bacillus subtilis subsp. subtilis str. 168
Reported site sp.: Bacillus subtilis subsp. subtilis str. 168
Created by: Dinara Sagitova
Curation notes: -

Experimental Process

LacZ reporter assays showed that ilv-leu was under CcpA-dependent positive control. GRASP-DNA program revealed a CcpA binding motif in the ilv-leu promoter. Site-directed mutagenesis was used to introduce mutations into the putative CcpA binding site. DNase I footprinting with probes containing wild type and mutated CcpA binding site showed that the CcpA binding site was protected from digestion by DNase only in the wild type promoter.

Transcription Factor Binding Sites

Sites reported in the paper
Sites matched in the genome

ATGAAAGCGTATACA

Gene Regulation

Regulated genes for each binding site are displayed below. Gene regulation diagrams show binding sites, positively-regulated genes, negatively-regulated genes, both positively and negatively regulated genes, genes with unspecified type of regulation. For each indvidual site, experimental techniques used to determine the site are also given.

Site sequence	Regulated genes	Gene diagram	Experimental techniques	TF function	TF type
ATGAAAGCGTATACA	ilvB, ilvH, ilvC,		Experimental technique details Beta-gal reporter assay Beta-gal reporter assay Reporter assay using the beta-galactosidase (lacZ) gene. The lacZ gene is typically fused to the promoter of interest. Differential regulation of the promoter mediated by the TF is assessed by induction of the system and evaluation of lacZ expression. Bacteria expressing lacZ appear blue when grown on a X-gal medium. The assay is often performed using a plasmid borne construction on a lacZ(def) strain. - Experimental technique details Consensus search (ECO:0005624) Consensus search - ECO:0005624 This is a weak form of in-silico search, in which the consensus sequence for the motif is compared to genomic positions and the number of mismatches (between candidate site and consensus) is used as a measure of site-quality. - Experimental technique details DNAse footprinting (ECO:0005631) DNAse footprinting - ECO:0005631 The DNAse foot-printing method starts by focusing on a given region of interest (e.g. a promoter region) and amplifying it by PCR to obtain lots of sample. It then throws in the TF and then the DNAse. The mix is left to stir for a short time and then gel electrophoresis is run to compare the pattern of fragments in a control (no TF) and in the sample. If the TF has bound the sample, it will have protected a stretch of DNA (encompassing some fragments of the control) and thus those fragments will not appear in the sample gel. The fragments can then be cut-out from the gel, purified and sequenced to obtain the sequence of the protected region. This is often used to identify the binding motif of a TF for the first time. The foot-printing will typically resolve the protected region down to 50-100 bp, and the sequence can be then examined for possible TF-binding sites either by eye of using a computer search. - Experimental technique details Site directed mutagenesis (ECO:0005667) Site directed mutagenesis - ECO:0005667 Target-specific mutation, as opposed to non-specific mutation. In the context of TF-binding sites, site-directed mutagenesis is typically used to establish/confirm the specific sequence and location of a site, often in tandem with EMSA. Different positions of a putative binding site are mutated to non-consensus (or random) bases and binding to the mutated site is evaluated through EMSA or other means. Often implemented only in conserved motif positions or serially through all positions of a site. -	activator	not specified