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- Title
BtuB TonB-dependent transporters and BtuG surface lipoproteins form stable complexes for vitamin B<sub>12</sub> uptake in gut Bacteroides.
- Authors
Abellon-Ruiz, Javier; Jana, Kalyanashis; Silale, Augustinas; Frey, Andrew M.; Baslé, Arnaud; Trost, Matthias; Kleinekathöfer, Ulrich; van den Berg, Bert
- Abstract
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. Uptake of vitamin B12 is important for colonisation of the gut by Bacteroides species. Here the authors characterise B12 uptake in Bacteroides thetaiotaomicron, mediated by outer membrane protein complexes consisting of surface-exposed BtuG lipoproteins and BtuB TonB-dependent transporters.
- Subjects
BACTEROIDES; LIPOPROTEINS; BACTEROIDES fragilis; VITAMINS; MEMBRANE transport proteins; MEMBRANE proteins; BLOOD lipoproteins
- Publication
Nature Communications, 2023, Vol 14, Issue 1, p1
- ISSN
2041-1723
- Publication type
Article
- DOI
10.1038/s41467-023-40427-2