Molecular dynamics simulation of the transmembrane subunit of BtuCD in the lipid bilayer.

Based on the crystal structure of the vitamin B(12) transporter protein of Escherichia coli (BtuCD) a system consisting of the BtuCD transmembrane domain (BtuC) and the palmitoyloleoyl phosphatidylcholine (POPC) lipid bilayer was constructed in silica, and a more-than-57-nanosecond molecular dynamics (MD) simulation was performed on it to reveal the intrinsic functional motions of BtuC. The results showed that a stable protein-lipid bilayer was obtained and the POPC lipid bilayer was able to adjust its thickness to match the embedded BtuC which underwent relatively complicated motions. These results may help to understand the mechanism of transmembrane substrate transport at the atomic level.