Functional and structural characterization of an ECF-type ABC transporter for vitamin B12
- University of Groningen, Netherlands
- University of Campinas, Brazil
- Stockholm University, Sweden
Abstract
Vitamin B12 (cobalamin) is the most complex B-type vitamin and is synthetized exclusively in a limited number of prokaryotes. Its biologically active variants contain rare organometallic bonds, which are used by enzymes in a variety of central metabolic pathways such as L-methionine synthesis and ribonucleotide reduction. Although its biosynthesis and role as co-factor are well understood, knowledge about uptake of cobalamin by prokaryotic auxotrophs is scarce. Here, we characterize a cobalamin-specific ECF-type ABC transporter from Lactobacillus delbrueckii, ECF-CbrT, and demonstrate that it mediates the specific, ATP-dependent uptake of cobalamin. We solved the crystal structure of ECF-CbrT in an apo conformation to 3.4 Å resolution. Comparison with the ECF transporter for folate (ECF-FolT2) from the same organism, reveals how the identical ECF module adjusts to interact with the different substrate binding proteins FolT2 and CbrT. ECF-CbrT is unrelated to the well-characterized B12 transporter BtuCDF, but their biochemical features indicate functional convergence.
Data availability
Diffraction data have been deposited in PDB under the accession code 6FNP.
Article and author information
Author details
Funding
Nederlandse Organisatie voor Wetenschappelijk Onderzoek
- Josy ter Beek
- Albert Guskov
- Dirk Slotboom
European Molecular Biology Organization
- Joana A Santos
- Stephan Rempel
Horizon 2020 Framework Programme
- Dirk Slotboom
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2018, Santos 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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Functional and structural characterization of an ECF-type ABC transporter for vitamin B12
eLife 7:e35828.
https://doi.org/10.7554/eLife.35828
