FIG. 4.

Schematic map of the S. thermophilus sufCDS iscU sufB cluster. Genes are indicated by gray arrows, and the positions of putative start and stop codons are given (in base pairs) below the map. The sites of the insertion of the pGh9:ISS1 plasmid into sufD (ossI)- and iscU (ossJ)-disrupted mutants are indicated by filled triangles. The broken arrow indicates the position of the suf cluster putative promoter. The putative rho-independent terminator is represented as hairpin loop. Fragments used for the generation of the nonpolar mutants are represented by open boxes. An asterisk indicates the position of the EcoRV restriction site causing the replacement of Cys₉₇ with a Tyr in the iscU₉₇ mutant.