A physical map for Mycoplasma capricolum Cal. kid with loci for all known tRNA species.

Figure 1. Genetic map for M. capricolum (ATCC 27343) with restriction sites for various endonucleases labelled by abbreviations as defined in te*t. Designation of sites with the suffices A, B, C, D etc is used in relation to the single digest restriction fragment which lies below a site on the map. The circular genome is shown linearised from the Bgl\ site within leuT. Symbols identifying the loci are defined in Table 1. Symbols: —, probe hybridized with fragments on both sides of the indicated cleavage site; I, hybridisation with the probe was confined to sequences between the restriction sites at the ends of the vertical line. (Bs), Sail (St), Smal (Sm) and Xhol (Xo) were located as previously described for M. mycoides (3) and Ureaplasma urealyticum (4), whereas the BamW sites were mapped relative to BgR. sites by reciprocal 2D-PFGE (5). This map agreed with the map of Miyata and Fukumura (1) except our map showed 3 extra AspllSl (=Kpn\) sites (AsA, E and F, Fig. 1) defining additional fragments of 26, 4 and 3 kbp. We have observed that M. capricolum Cal kid from another source (NCTC 10133) lacks the site (AsA in Fig. 1) defining the 26 kbp fragment. Lu et al. reported at the IOM meeting (6) that the replication origin was within fragments BamHl-H or -I and the terminus within BamHlC. The loci listed in Table 1 and shown in Fig. 1 were mapped by probing with appropriate cloned genes as described previously (3,7). They included the complete set of tRNA genes (thirty) identified for this organism as well as a gene encoding msRNA, a new small RNA from M. capricolum (8). The latter has a potential secondary structure with features common to eukaryotic 7SL RNA, eubacterial 4.5Sand scRNA and archaebacterial 7S RNA (9). The gene for a closely similar RNA has been recently cloned from M. mycoides subsp. capri (10). The two rRNA operons (rmA, rrnB) were differentiated by a sequence upstream