FIG. 4.

Fine mapping of the deletion join end. On top is shown the schematic alignment of the lacS loci, considered in this study, on the P2 (S.so P2; positions are indicated in mega-base pairs) and Gθ (S. so Gθ) Sulfolobus chromosomes. The main difference resulted from the insertion of an ISC element (sso3018) in the 3′ end of ORF sso3017 (the bar and arrow indicate the position of the insertion), namely, the lacTr gene, encoding a putative lactose transporter. The extreme 5′ DNA fragment of the 15-kbp region used for Southern analysis was dissected to produce two probes that showed one-band cross-hybridization patterns (A and B), on both the wild-type (P) and mutant (M) genomic DNAs, digested with EcoRI (two left lanes of each gel) and XbaI (two right lanes of each gel). The EcoRI DNA fragment from the mutant genomic DNA corresponding to the 1,250-bp band was cloned, sequenced (C), and compared with the full sequence of the S. solfataricus P2. The larger region of the fragment was identical to part of ORF sso3012, encoding a putative ABC transporter (uppercase letters), abruptly interrupted by a shorter DNA element (lowercase boldface letters) showing identity with multiple repetitive sequences found on the P2 genome and indicated as transposase-coding ICS1058 elements (sso3023).