Curation Information

ExpR coordinates the expression of symbiotically important, bundle-forming Flp pili with quorum sensing in Sinorhizobium meliloti.;Zatakia HM, Nelson CE, Syed UJ, Scharf BE;Applied and environmental microbiology 2014 Apr; 80(8):2429-39 [24509921]
ExpR [Q92L12, view regulon]
Reported TF sp.
Sinorhizobium meliloti 1021
Reported site sp.
Sinorhizobium meliloti 1021
Created by
Dinara Sagitova
Curation notes

Experimental Process

pilA1-lacZ fusions in the wild-type SM1021 and the Sm1021 ExpR+ strains revealed ExpR-mediated repression of pilA1 in the presence of an acyl homoserine lactone. EMSA confirmed that AHL-activated ExpR binds to the pilA1 promoter. DNase I footprinting identified a 28-bp region protected by ExpR. The protected sequence was aligned with four previously identified ExpR binding sites. This confirmed that ExpR bound to an ExpR consensus in the pilA1 promoter.

Transcription Factor Binding Sites


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
... ... pilA1 SMc04115 cpaA1 cpaB1 cpaC1 SMc04110 cpaE1 cpaF1 SMc02821 SMc02822
Experimental technique details Beta-gal reporter assay - Experimental technique details DNAse footprinting (ECO:0005631) - Experimental technique details EMSA (ECO:0001807) - Experimental technique details Multiple sequence alignment (MSA) (ECO:0005556) - repressor not specified