65 Ci/mmol), and [3H]-adenine ([3H]-Ade, 27.2 Ci/mmol) were purchased from PerkinElmer. [3H]-guanine ([3H]-Gua, 10.7 Ci/mmol) and [5-3H]-deoxyuridine 5’-monophosphate

([3H]-dUMP, 27 Ci/mmol) were from Moravek Biochemicals, Inc. The nucleoside and nucleobase analogs library [36] was kindly provided by Professor Pär Nordlund, from the Karolinska Institute, Stockholm, OSI906 Sweden. Phosphoribosyl pyrophosphate (PRPP), dipyridamole, tetracycline, Pexidartinib and nonradioactive Hx and Gua were from Sigma-Aldrich. Mpn culture, and the effects of nucleoside and nucleobase analogs on growth and metabolism Nucleoside and nucleobase analogs were dissolved in dimethyl sulfoxide (DMSO) as stock solutions and diluted with Mpn culture medium to the desired concentration immediately prior to use. The DMSO concentration in the final dilution was < 1%, which would not

interfere with Mpn growth. Mpn laboratory strain M129 wild type and a thyA mutant selleck inhibitor strain [31] were used in this study. Mpn was cultured at 37°C in a CO2 incubator using 75 cm2 tissue culture flasks containing 50 ml Hayflick’s medium, and harvested at day 4 when the medium color change was observed [49]. The cells were harvested and the pellet was resuspended in 6 ml fresh medium and the cfu/ml was determined by serial dilution (10-fold) and plating on broth agar plate. Colonies was counted and cfu/ml was calculated. Inhibition studies were performed in 96-well plates containing 200 μl Mpn culture (approximately

106 cfu ml-1) in Hayflick’s medium and 200 μl each compound in series dilutions (2-fold) with the growth medium, with three to four replicas. The plates were sealed with clear adhesive sheets and incubated at 37°C incubator. Absorbance ratio at 450 nm and 560 nm was used as Mpn growth index, which was measured daily, and by visual detection for at least 8 days, as previously described [32]. In the absence of inhibitor, the culture medium turned yellow on day 4. Controls were cultured in the presence of 2 μg/ml tetracycline, which showed no growth for up to 8 days. Medium was placed in four wells per plate for controls, which see more showed no color change during the incubation period. The MICs (minimal inhibitory concentration required to inhibit Mpn growth to 90%) were determined as the lowest concentration at which the growth index was ≈ 10% of the control values (at the time when the control culture medium color turned yellow), essentially as described [50]. Nucleoside and nucleobase uptake and metabolism was done with the wild type strain, which was cultured in 25 cm2 tissue culture flasks, inoculated with 1 ml stock culture (1 × 108 cfu/ml) Mpn, in the presence of tritium labeled dT, Hx, Gua, Ade or Ura (1 μCi ml-1) and the presence or absence of nucleoside and nucleobase analogs (10 μM) and incubated at 37°C for 70 hours. The cells were harvested and analyzed essentially as described [31].