Elucidation of the zinc-dependent regulation in Amycolatopsis japonicum enabled the identification of the ethylenediamine-disuccinate ([S,S]-EDDS) genes

作者：Spohn Marius; Wohlleben Wolfgang; Stegmann Evi^*

来源：Environmental Microbiology, 2016, 18(4): 1249-1263.

DOI：10.1111/1462-2920.13159

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 ZnuABC(Aj). The Zur-binding motif, recognized by the zinc-bound Zur protein in the upstream region of znuABC(Aj), 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 zur mutant, which offers now the opportunity to develop a biotechnological process.

• 出版日期2016-4