Genetic organization of the C. salexigens eupR region and constructions derived from it. (A) C. salexigens genomic region containing eupR and Csal869, encoding its putative cognate histidine kinase, the mntH-mntR genes related to manganese transport, and the acs gene encoding a putative acetyl-CoA synthase. Promoters are indicated by angled arrows. The transcriptional terminator downstream of eupR is shown as a lollipop. (B) The same genomic region in C. salexigens CHR95. The insertion of Tn1732 deleted acs, eupR and mntR. (C) Generation of the eupR strain. eupR was inactivated by the insertion of an Ωaac cassette, which carries resistance genes for geneticin and gentamicin, into its unique site Hpa I site (H). (D) Generation of the mntR strain. mntR was inactivated by the insertion of an Ω cassette, which carries resistance genes for streptomycin and spectinomycin, into its unique site Hpa I site (H).