Curation Information

Publication: Vibrio cholerae VibF is required for vibriobactin synthesis and is a member of the family of nonribosomal peptide synthetases.;Butterton JR, Choi MH, Watnick PI, Carroll PA, Calderwood SB;Journal of bacteriology 2000 Mar; 182(6):1731-8 [10692380]
TF: Fur [A5F6G4, view regulon]
Reported TF sp.: Vibrio cholerae O395
Reported site sp.: Vibrio cholerae O395
Created by: Dinara Sagitova
Curation notes: -

Experimental Process

vibF-lacZ reporter assays showed that vibF was negatively regulated by Fur in the presence of high iron concentration. Primer extension analysis localized the vibF transcription start site. Visual sequence inspection identified a putative Fur binding site homologous to the E.coli Fur consensus. DNase I footprinting confirmed that Fur binds to its target operator site in the vibF promoter in the presence of iron.

Transcription Factor Binding Sites

Sites reported in the paper
Sites matched in the genome

GATAATGATTATTATTAAC

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
GATAATGATTATTATTAAC	vibF		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 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 Visual sequence inspection (nan) Visual sequence inspection - nan Visual inspection of promoter region to identify putative binding sites based on previous knowledge -	repressor	not specified