4FI3

Structure of vitamin B12 transporter BtuCD-F in a nucleotide-bound state

Summary for 4FI3

• Entry DOI: 10.2210/pdb4fi3/pdb
• Descriptor: Vitamin B12 import system permease protein BtuC, Vitamin B12 import ATP-binding protein BtuD, Vitamin B12-binding protein, ... (5 entities in total)
• Functional Keywords: abc transporter, vitamin b12 transport, atp binding, membrane, transport protein
• Biological source: Escherichia coli; More
• Cellular location: Cell inner membrane; Multi-pass membrane protein: P06609; Cell inner membrane; Peripheral membrane protein: P06611; Periplasm: P37028
• Total number of polymer chains: 5
• Total formula weight: 158772.68

Authors

Korkhov, V.M.,Mireku, S.A.,Locher, K.P. (deposition date: 2012-06-07, release date: 2012-09-19, Last modification date: 2024-10-09)

Primary citation

Korkhov, V.M.,Mireku, S.A.,Locher, K.P.
Structure of AMP-PNP-bound vitamin B12 transporter BtuCD-F.
Nature, 490:367-372, 2012

PubMed Abstract: The ATP-binding cassette (ABC) transporter BtuCD mediates the uptake of vitamin B(12) across the inner membrane of Escherichia coli. Previous structures have shown the conformations of apo states, but the transport mechanism has remained unclear. Here we report the 3.5 Å crystal structure of the transporter-binding protein complex BtuCD-BtuF (BtuCD-F) trapped in an β-γ-imidoadenosine 5'-phosphate (AMP-PNP)-bound intermediate state. Although the ABC domains (BtuD subunits) form the expected closed sandwich dimer, the membrane-spanning BtuC subunits adopt a new conformation, with the central translocation pathway sealed by a previously unrecognized cytoplasmic gate. A fully enclosed cavity is thus formed approximately halfway across the membrane. It is large enough to accommodate a vitamin B(12) molecule, and radioligand trapping showed that liposome-reconstituted BtuCD-F indeed contains bound B(12) in the presence of AMP-PNP. In combination with engineered disulphide crosslinking and functional assays, our data suggest an unexpected peristaltic transport mechanism that is distinct from those observed in other ABC transporters.

PubMed: 23000901
DOI: 10.1038/nature11442

Experimental method

X-RAY DIFFRACTION (3.466 Å)