FIG 2 .

Analysis of the arc gene complex expression. (A) RT-PCR analysis of arc gene cluster regions. Total mRNA was isolated from S. pneumoniae grown in THY medium, and random primers were used to amplify cDNA. Genomic DNA (gDNA) and RNA served as positive and negative controls, respectively. The following PCR fragments representing arc gene and intergenic sequences were amplified after RT: FI, arcAB intergenic region; FII, arcBC intergenic region; FIII, arcCD intergenic region; FIV, arcDT intergenic region. The enolase gene was used as a positive control. Lanes M contained molecular size markers. (B) Northern blot analysis of arcABCDT transcripts in wild-type (wt) S. pneumoniae D39 and TIGR4 and in the isogenic TIGR4 ΔarcA-C, ΔarcA-T ΔargR2, ΔargR1, and ΔahrC deletion mutants, respectively. Total RNA isolated from cultures grown in CDM to an OD₆₀₀ of 0.4 was hybridized with DIG-labeled RNA probes for arcA (P704, P611), arcB (P933, P934), arcC (P935, P936), and arcDT (P705, P613). Methylene blue was used to verify the amount of RNA on hybridization membranes.