The -10 region adjacent to open reading frames is a common expression pattern in .

Gene transcription and translation are fundamental processes that underpin the vitality of living organisms. In bacteria, the classic promoter elements for transcription include the -35 region and the -10 region, whereas the ribosome binding site (RBS) is essential for translation. Our investigation of the upstream sequences of ORFs in has confirmed a -10 region-like motif, which appears as 5'-TANNNT-3' (-10-motif). Through rigorous experimental validation, we have established that this -10-motif functions as the classical -10 region of the promoter during transcription, responsible for initiating transcription of leaderless genes (mRNA products that do not have or only have a very short 5'-UTR), and exhibits specific spacing requirements relative to the ORF. Moreover, our findings suggest that sequences containing -10-motif can serve as promoters for and introduction of the -35 region at appropriate positions can significantly enhance transcription levels. Genomic analysis revealed that the -10-motif located a few base pairs (bp) upstream of ORFs is common within the () phylum (also known as ) and responsible for the transcriptional initiation of leaderless genes. Given these insights, we propose that the -10 region adjacent to the ORF for gene expression via leaderless mRNA constitutes an important mode of expression in the phylum, which may contribute to the extraordinary environmental adaptability observed in this group of microorganisms.