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Elife. 2018 Sep 18;7. pii: e37138. doi: 10.7554/eLife.37138.

Human gut Bacteroides capture vitamin B12 via cell surface-exposed lipoproteins.

Author information

1
Department of Microbial Pathogenesis, Yale University, New Haven, United States.
2
Microbial Sciences Institute, Yale University, New Haven, United States.
3
W.M. Keck Biotechnology Resource Laboratory, Yale University School of Medicine, New Haven, United States.

Abstract

Human gut Bacteroides use surface-exposed lipoproteins to bind and metabolize complex polysaccharides. Although vitamins and other nutrients are also essential for commensal fitness, much less is known about how commensal bacteria compete with each other or the host for these critical resources. Unlike in Escherichia coli, transport loci for vitamin B12 (cobalamin) and other corrinoids in human gut Bacteroides are replete with conserved genes encoding proteins whose functions are unknown. Here we report that one of these proteins, BtuG, is a surface-exposed lipoprotein that is essential for efficient B12 transport in B. thetaiotaomicron. BtuG binds B12 with femtomolar affinity and can remove B12 from intrinsic factor, a critical B12 transport protein in humans. Our studies suggest that Bacteroides use surface-exposed lipoproteins not only for capturing polysaccharides, but also to acquire key vitamins in the gut.

KEYWORDS:

corrinoid; gut; infectious disease; intrinsic factor; lipoprotein; microbiology; microbiome; vitamin B12

PMID:
30226189
PMCID:
PMC6143338
DOI:
10.7554/eLife.37138
[Indexed for MEDLINE]
Free PMC Article

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