Identification of the 10Sa RNA structural gene ofMycobacterium tuberculosis

In the course of screening a gene bank of Mycobacterium tuberculosis (1) with cDNA to RNA from M.tuberculosis, we have isolated a clone, pAK51, which contains significant sequence homology with Alcaligenes eutrophus lOSa RNA (57% identity) and Escherichia coli lOSa RNA (54% identity). The lOSa RNA has been described as a stable RNA (2, 3). The conservation of primary sequences does not end at the 3' end of the mature lOSa RNA but extends further downstream. The lOSa structural RNA gene is located within a 1 kb Pstl genomic fragment of DNA from M. tuberculosis H37Rv and M. tuberculosis H37Ra (Figure 1A). When total RNA isolated from M. tuberculosis H37Rv and M.tuberculosis H37Ra was probed with the putative lOSa RNAcoding region from pAK51, hybridization was obtained with RNA approximately 390—400 bases in length (Figure IB). Interestingly, the sequence located in the 3' terminal of lOSa RNA showed strong homology (4) with the pseudouridine arm of tRNA genes from several organisms (Figure 2).