BtuG2 lipoprotein (BtuG2)

BtuG2 is a surface-exposed lipoprotein found in Bacteroides species from the human gut microbiome, where it is involved in scavenging vitamin B12 (cobalamin) and related corrinoids from the environment[2][4][5]. BtuG2 forms a stable complex with the TonB-dependent transporter BtuB2 in the bacterial outer membrane, acting as an extracellular lid and enabling efficient transport of B12 into the cell[1]. It adopts a seven-bladed beta-propeller fold, with a central cavity forming the binding site for corrinoids, including cobalamin and its analogs[1]. BtuG2 binds vitamin B12 with extremely high (femtomolar) affinity, enabling Bacteroides to acquire this vital cofactor from complexed or host-bound sources such as intrinsic factor[2]. This protein is crucial for microbial fitness in competitive gut environments, but is not recognized as a therapeutic target, enzyme, or receptor in human medicine[2]. No direct drug interactions, mechanisms of action, or biomarker data related to BtuG2 are reported in the scientific literature.