Fig 3.

Energy poisoning inhibition and rescue analysis of G3P and DHAP transport in purified R. prowazekii. Transport assays were performed with purified R. prowazekii suspended in modified SPGMg²⁺ buffer at 34°C over a 25-min time course for [¹⁴C]lysine (5 μM) (A), [¹⁴C]G3P (20 μM) (B), or [³²P]DHAP (10 μM) (C). The inhibition data for each time point are presented as a percentage of the corresponding control (no energy poison) transport assay. Data points are the average of technical triplicates of at least three independent rickettsial preparations. Rickettsiae were preincubated for 10 min with CCCP (10 μM), KCN (1 mM), or a combination of KCN (1 mM) and venturicidin (Ven, 20 μg ml⁻¹), and transport assays were initiated by the addition of radiolabeled substrates. After 10 min of transport, ATP (2.5 mM) was added to the uptake mixture in an attempt to reverse the energy-poisoning effect (indicated with an arrow). The subsequent data points are presented as a percentage of the 10-min control (no energy poison) time point. In all cases, control assays with no inhibitors were carried out in parallel (data not shown). Error bars represent the standard deviations of the means.