Iron-sulfur (FeS) centers are among the most widely spread prosthetic groups in nature. They contribute to catalysis, electron transfer or redox sensing. Organisms construct and insert FeS clusters into hundreds of proteins using so-called FeS biogenesis systems ISC and SUF, which are ubiquitous and conserved in most living organisms on Earth.
In vivo analysis of the FeS biosynthesis has been for long hampered by its essentiality. In E. coli for instance, deleting both the ISC and SUF genes is lethal. In the late 90’s however, this bottleneck was alleviated by setting up a genetic by-pass exploiting eucaryotic genes. Briefly, in E. coli, synthesis of the essential precursor, isopentenyl diphosphate (IPP), depends upon a a pathway that includes two FeS enzymes and methylerythritol phosphate (MEP) as a precursor. Hence lack of ISC and SUF is lethal in particular because IspG and IspH are not getting their cluster and IPP is not synthesized. In eukaryotes, IPP is produced by a different pathway, which uses mevalonate (MVA) as a precursor, and no FeS enzymes to convert it to IPP. Therefore, we introduced a synthetic version of the eucaryotic pathway in E. coli and found it was able to rescue a strain lacking both ISC and SUF systems (1,2). The resulting strain had since been used and studied in several laboratories around the world in (i) permitting genetic investigations of the precise role of different elements of the ISC and SUF systems, (ii) describing the maturation pathways of over 20 FeS proteins in E. coli, (iii) discovering additional new FeS biogenesis factors and (iv) producing different FeS proteins under their apo form for further biochemical and/or biotechnological purposes. This project aims at characterizing the genome of this engineered strain we will refer to as the FBE605 strain.
