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BtuB TonB-dependent transporters and BtuG surface lipoproteins form stable complexes for vitamin B12 uptake in gut Bacteroides

Lookup NU author(s): Dr Javier Abellon-RuizORCiD, Dr Augustinas SilaleORCiD, Dr Andrew FreyORCiD, Dr Arnaud Basle, Professor Matthias TrostORCiD



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© 2023, Springer Nature Limited.Vitamin B12 (cobalamin) is required for most human gut microbes, many of which are dependent on scavenging to obtain this vitamin. Since bacterial densities in the gut are extremely high, competition for this keystone micronutrient is severe. Contrasting with Enterobacteria, members of the dominant genus Bacteroides often encode several BtuB vitamin B12 outer membrane transporters together with a conserved array of surface-exposed B12-binding lipoproteins. Here we show that the BtuB transporters from Bacteroides thetaiotaomicron form stable, pedal bin-like complexes with surface-exposed BtuG lipoprotein lids, which bind B12 with high affinities. Closing of the BtuG lid following B12 capture causes destabilisation of the bound B12 by a conserved BtuB extracellular loop, causing translocation of the vitamin to BtuB and subsequent transport. We propose that TonB-dependent, lipoprotein-assisted small molecule uptake is a general feature of Bacteroides spp. that is important for the success of this genus in colonising the human gut.

Publication metadata

Author(s): Abellon-Ruiz J, Jana K, Silale A, Frey AM, Baslé A, Trost M, Kleinekathöfer U, van den Berg B

Publication type: Article

Publication status: Published

Journal: Nature Communications

Year: 2023

Volume: 14

Online publication date: 05/08/2023

Acceptance date: 27/07/2023

Date deposited: 01/09/2023

ISSN (electronic): 2041-1723

Publisher: Nature Publishing Group


DOI: 10.1038/s41467-023-40427-2

PubMed id: 37543597


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Funder referenceFunder name
214222/Z/18/ZWellcome Trust
215542/Z/19/ZWellcome Trust
Wellcome Trust