Lipoate-binding proteins and specific lipoate-protein ligases in microbial sulfur oxidation reveal an atypcial role for an old cofactor
Abstract
Many Bacteria and Archaea employ the heterodisulfide reductase (Hdr)-like sulfur oxidation pathway. The relevant genes are inevitably associated with genes encoding lipoate-binding proteins (LbpA). Here, deletion of the gene identified LbpA as an essential component of the Hdr-like sulfur-oxidizing system in the Alphaproteobacterium Hyphomicrobium denitrificans. Thus, a biological function was established for the universally conserved cofactor lipoate that is markedly different from its canonical roles in central metabolism. LbpAs likely function as sulfur-binding entities presenting substrate to different catalytic sites of the Hdr-like complex, similar to the substrate-channeling function of lipoate in carbon-metabolizing multienzyme complexes, e.g. pyruvate dehydrogenase. LbpAs serve a specific function in sulfur oxidation, cannot functionally replace the related GcvH protein in Bacillus subtilis and are not modified by the canonical E. coli and B. subtilis lipoyl attachment machineries. Instead, LplA-like lipoate-protein ligases encoded in or in immediate vicinity of hdr-lpbA gene clusters act specifically on these proteins.
Data availability
All data generated or analysed during this study are included in the manuscript and supporting files. Source data files have been provided for Figures 2 and 3.
Article and author information
Author details
Funding
Deutsche Forschungsgemeinschaft (Da 351/8-1)
- Christiane Dahl
National Institutes of Health (AI15650)
- John E Cronan
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2018, Cao et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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