In the same way, single-site recombination events were avoided and the correct double recombinant event guaranteed by means of phenotypic and genotypic analyses. Furthermore, sequences flanking the recombinant sites Silmitasertib supplier of the lineages constructed and the confirmation that the regions of interest were indeed correctly in frame was possible by sequencing experiments. This demonstrates that the promoter region of the recombinant lineage was correct and that the gene could be expressed without any problems. Proper

expression of these proteins was confirmed (Riboldi, Oliveri & Frazzon, unpublished data). To determine whether the SUF genes could complement ISC elements in the [Fe–S] cluster assembly in A. vinelandii, attempts were made to inactivate various ISC genes in the above strains. Plasmids containing kanamycin resistance cartridges truncating the housekeeping ISC RG-7204 gene were used to transform the above strains, with selection for kanamycin resistance on media containing arabinose. The combinations

tested included: sufU or sufB as scaffolds, instead of iscU (AES4 or AES5 × pDB1018); sufS as desulfurase, instead of iscS (AES3 × pDB933K); sufSU as desulfurase, instead of iscS (AES6 × pDB933K); sufC as the ATPase partner of the system, instead of hscA (AES1 × pDB1005); sufD against all biological possibilities (AES2 × pDB1018, pDB933K, or pDB1005); and finally, the entire operon sufCDSUB, instead of iscSUA-hscBA-fdx (AES7 × pDB1370). No viable kanamycin-resistant strains were obtained, indicating that the inactivation of the ISC protein was lethal despite expression of the SUF-correspondent factor, and suggesting that the SUF operon of E. faecalis is not able to complement the ISC elements of A. vinelandii. Escherichia coli corresponds to a Proteobacteria representative that possesses both ISC and SUF systems for [Fe–S] cluster formation. As in A. vinelandii, the ISC system serves as the housekeeping machinery, but instead of having the NIF system, E. coli possesses the SUF system as an alternative system induced in cases of oxidative stress and iron limitation. To determine

whether the E. faecalis SUF operon is able to complement the ISC system of E. coli, in vivo experiments ifenprodil were performed using mutants lacking iscS (see Table 1). The iscS mutants require thiamine, nicotinic acid, and branched chain amino acids for growth. This auxotrophic phenotype eliminates the need for E. coli SUF mutation to verify E. coli ISC complementation. Thus, the strains will only be viable if there is some component complementing iscS functions related to the amino acid homeostasis (classic function of type I of cysteine desulfurase related to [Fe–S] cluster formation), as much as for [Fe–S] cluster formation. Two strains of differing genetic background were utilized – PJ23 and CL100. The respective parental strains (TL254 and MC1061, respectively) were also assayed.