Candidate motifs identified upstream of the nucleotide biosynthetic genes, upstream location, site-directed mutagenesis and results of reporter assays. Motifs NTBA and NTBB show redundancy in function by negatively affecting gene expression from the UPRT promoter among the nucleotide metabolism genes. (a) Sequence logos represent the consensus sequence for each candidate motif. The y-axis represents information content at each position. (b) Occurrences and positions of the motifs in the promoter region relative to the translational start site of each gene. The gene names are abbreviated as shown in Table 1. The underlined gene name indicates the representative promoter used in reporter assays. Motif NTBA, found in both E. tenella and T. gondii, is denoted by a circle and motif NTBB, exclusive to T. gondii, is denoted by a square. (c) The WT motifs and their mutagenized (MUT) versions in the representative promoter are represented. (d) The graphs depict luciferase activity as ratios of firefly:renilla activity in relative luciferase units (RLU) from the different constructs containing either WT or mutagenized versions of NTBA, NTBB, or both motifs. All luciferase readings are relative to an internal control (α-tubulin-renilla). Error bars represent standard error calculated across the means of three independent electroporations. p-values describe the probability that the difference in expression between the WT and mutagenized promoters may be due to chance.
Mullapudi et al. Genome Biology 2009 10:R34 doi:10.1186/gb-2009-10-4-r34