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. 2014 Sep 10;5:4868. doi: 10.1038/ncomms5868

Figure 3. Maltose- and palatinose-specific MalR regulators have different DNA-binding sites.

Figure 3

Representative flow cytometry histograms of populations of fluorescent reporter strains carrying different types of DNA-binding sites in the promoters of a maltose-specific gene MAL32 (red block arrow), or a palatinose-specific IMA5 (blue block arrow), grown in maltose or palatinose. CGG-containing binding sites found in promoters of palatinose-specific genes are depicted as blue rectangles, CGC-containing DNA-binding sites found in promoters of maltose-specific gene are depicted as red rectangles. (a) DNA-binding specificity of the palatinose-specific regulator Yfl052w. (1) A fluorescently tagged IMA5 gene under its native promoter shows a normal level of IMA5 expression activated by Yfl052w in palatinose. (2) Deletion of the Yfl052w binding site abolishes the expression of IMA5. (3) A fluorescently tagged maltose-specific MAL32 under its native promoter shows no expression on palatinose and is used to quantify autofluorescence. Introduction of a Yfl052w binding site from the promoter of IMA5 (4) or IMA1 (5) in front of the fluorescently tagged MAL32 gene makes the expression of this gene responsive to palatinose. (6) Deletion of YFL052W abolishes the expression of the MAL32 gene from (4). (b) DNA-binding specificity of the maltose-specific regulator Malx3. (1) A fluorescently tagged MAL32 under its native promoter shows a normal level of MAL32 expression activated by Malx3 in maltose. (2) Deletion of one Malx3 binding site decreases the expression levels of fluorescently labelled MAL32. (3) Deletion of all three Malx3 binding sites abolishes the expression of MAL32. (4) A fluorescently tagged IMA5 gene under its native promoter is used to show autofluorescence. Introduction of one (5), (6), two (7)–(9) or three (10) Malx3 binding sites in the promoter region of a fluorescently tagged IMA5 gene makes the expression of this gene responsive to maltose, with increasing number of binding sites resulting in higher expression levels. (11)–(13) Deletion of the maltose-specific regulator MALX3 abolishes the expression of strains from (7), (8) and (10). Each experiment was repeated at least three times with two biological replicates.