Characterization of a Minimal Type of Promoter Containing the -10 Element and a Guanine at the -14 or -13 Position in Mycobacteria.

Three key promoter elements, i.e., -10, -35, and TGN, are recognized by the σ subunit of RNA polymerase. Among them, promoters with the -10 element and either -35 or TGN are known to initiate transcription efficiently, but recent systematic analyses have identified a large group of promoters in that contain only a -10 consensus. How these promoters initiate transcription remains poorly understood. Here, we show that promoters containing the -10 element and an upstream G located at the -14 or -13 position can successfully initiate transcription in mycobacteria. Importantly, this new type of promoter is active in the absence of other promoter consensuses, suggesting that it is a minimal promoter type. Mutation of the upstream G in promoters decreased the efficiencies of their binding with RNA polymerase and their abilities to initiate transcription in both and analyses. A glutamic acid in σ region 3.0 is essential for recognizing G and G and is conserved in both principal and principal-like σ factors in mycobacteria, indicating that recognition of this minimal type of promoter might be a common mechanism for transcription initiation. Consistently, more than 70% of the identified promoters in contained G or G upstream of the conserved -10 element, and thousands of promoters in representative mycobacterial species have been predicted using the -10 consensus and G or G Altogether, our study presents a universal mechanism for transcription initiation from a minimal promoter in mycobacteria, which might also be applicable to other bacteria. In contrast to the detailed information for recognizing classic promoters in the model organism , very little is known about how transcription is initiated in the human pathogen In this study, we characterized a new type of promoter in mycobacteria that requires only a -10 consensus and an upstream G or G Residues important for recognizing the -10 element and the upstream G are conserved in σ and σ from mycobacterial species. According to such features, thousands of promoters in mycobacteria can be predicted using the -10 consensus and G or G, which suggests that transcription from this new type of promoter might be widespread. Our findings provide insightful information for characterizing promoters in mycobacteria.