title: Elucidation of the zinc-dependent regulation in Amycolatopsis japonicum enabled the identification of the ethylenediamine-disuccinate ([S,S]-EDDS) genes.
abstract: The actinomycete Amycolatopsis japonicum produces the complexing agent ethylenediamine-disuccinate ([S,S]-EDDS), which is an isomer of the widely industrially applied ethylenediamine-tetraacetate (EDTA). In contrast to EDTA, [S,S]-EDDS is readily biodegradable and is therefore an alternative with a favourable environmental profile. Biotechnological production of [S,S]-EDDS, however, is not currently possible because its biosynthesis is inhibited by low-micromolar zinc concentrations. Here we illustrate the development of a new strategy for identifying a biosynthetic pathway that is based on the elucidation of transcriptional regulation and the screening for binding sites of the respective regulator that controls the [S,S]-EDDS biosynthesis genes. To achieve this, we identified the zinc uptake regulator Zur in A. japonicum and showed that it mediates the repression of the zinc uptake system ZnuABCAj . The Zur-binding motif, recognized by the zinc-bound Zur protein in the upstream region of znuABCAj , was used to screen the genome, leading to the identification of the aes genes. Transcriptional analysis and shift assays reveal specific zinc-responsive regulation of the aes genes by Zur, and gene inactivation shows their involvement in [S,S]-EDDS biosynthesis. Zur-mediated zinc repression of the [S,S]-EDDS biosynthesis genes is abolished in a Δzur mutant, which offers now the opportunity to develop a biotechnological process.
authors.affiliation: Interfaculty Institute of Microbiology and Infection Medicine Tuebingen, Microbiology/Biotechnology, University of Tuebingen, 72076, Tuebingen, Germany.
authors.forename: Marius
authors.initials: M
authors.lastname: Spohn
authors.affiliation: Interfaculty Institute of Microbiology and Infection Medicine Tuebingen, Microbiology/Biotechnology, University of Tuebingen, 72076, Tuebingen, Germany.|Partner Site Tuebingen, German Centre for Infection Research (DZIF), Tuebingen, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wohlleben
authors.affiliation: Interfaculty Institute of Microbiology and Infection Medicine Tuebingen, Microbiology/Biotechnology, University of Tuebingen, 72076, Tuebingen, Germany.|Partner Site Tuebingen, German Centre for Infection Research (DZIF), Tuebingen, Germany.
authors.forename: Evi
authors.initials: E
authors.lastname: Stegmann
mesh_terms: D039903:Actinobacteria / Q000235:genetics* / Q000378:metabolism*; D001665:Binding Sites; D005029:Ethylenediamines / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D007473:Ion Channels / Q000235:genetics; D017136:Ion Transport / Q000235:genetics; D011401:Promoter Regions, Genetic; D013386:Succinates / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism*
chemical_list: D005029:Ethylenediamines; D007473:Ion Channels; D013386:Succinates; C041447:N,N'-ethylenediamine disuccinic acid; D015032:Zinc