Figure 7

A. phagocytophilum and XA promotes increased binding of tick nuclear proteins on the isoatp4056 promoter. (A) Schematic representation (not to scale) of the isoatp4056 genomic region comprising of 11 exons (indicated as E1-11) and a putative promoter and a TATA-binding region is shown. GenBank accession number for the genomic sequence is provided. The position of −191 and −142 is labeled considering + 1 for the first nucleotide of exon 1 (E1). (B) EMSA gel image showing increased shift of isoatp4056 TATA-binding promoter region in the presence of A. phagocytophilum. EMSAs were performed with the biotin-labeled isoatp4056 promoter TATA-binding regions and uninfected or A. phagocytophilum–infected ticks nuclear extract. Wedges indicate increasing amounts of nuclear extracts (1, 2, 4 µg). Probe and shifted bands are labeled. (C) EMSAs performed with the biotin-labeled isoatp4056 promoter TATA-binding region and mock or XA-treated A. phagocytophilum–infected tick cell nuclear extracts. Wedges indicate increasing amounts of nuclear extracts (1, 1.5 µg). Gel shifts and the isoatp4056-free probes are indicated with arrows. (D) Model for the role of IsOATP4056 and KAT in A. phagocytophilum survival in tick cells. A. phagocytophilum up-regulates isoatp4056 and kat genes upon entry into tick salivary gland cells (A). Upregulation of these genes results in the increased production of IsOATP4056 that could be targeted to the plasma membrane as a transporter for intake of extracellular XA shown as open asterisk (B). Upregulation of kat gene results in increased production of intracellular XA (closed asterisk) that could facilitate A. phagocytophilum replication and colonization (C) and/or influence isoatp4056 promoter to make more IsOATP4056 (D). Intake of extracellular XA (open asterisk) could also participate in the increase of A. phagocytophilum burden (E) or regulation of isoatp4056 promoter (F). A. phagocytophilum is shown as morulae in the vacuole (gray color). Picture is not drawn to the scale.