Figure 2. Transcription of the speF and Smr45C RNAs. (A) Nucleotide sequence (both DNA strands) of the SMc02983-SMc02984 IGR expressing the speF and Smr45C RNA elements. Numbering indicates coordinates in the S. meliloti 1021 genome. The -35 and -10 hexamers of the predicted σ⁷⁰-dependent promoters (P1 and P2) are boxed. Black arrowheads indicate the predicted start and end of the speF RNA as annotated in the Rfam database. Nucleotide positions of 5′ and 3′ ends previously determined for the Smr45C sRNA are boxed and a double arrowhead in red indicates its TSS. A double arrowhead in green indicates the predicted TSS for speF from the P2 promoter. The proposed speF and Smr45C coding sequences are in green and red letters, respectively. (B) Northern analysis of speF and Smr45C RNAs. Sequences of the 25-mer oligonucleotides used to probe the membranes are underlined in (A). RNA samples were: TY, log TY cultures; TY(S), stationary phase TY cultures; MM, log Minimal Medium cultures; MM(L), luteolin-induced log MM cultures; N, mature alfalfa nodules. Molecular weight markers are shown to the right of the panels. 5S RNA was also probed as RNA loading control.