The outer membranes of Gram-negative bacteria possess transport proteins essential for
uptake of scarce nutrients. In TonB-dependent transporters, a conserved sequence of seven …

Gram-negative bacteria possess specialized active transport systems that function to
transport organometallic cofactors or carriers, such as cobalamins, siderophores, and …

Uptake of cobalamins by the transporter protein BtuB in the outer membrane of Escherichia
coli requires the proton motive force and the transperiplasmic protein TonB. The Ton box …

In Gram-negative bacteria, the import of essential micronutrients across the outer membrane
requires a transporter, an electrochemical gradient of protons across the inner membrane …

Transport of vitamin B12 across the outer membrane of Escherichia coli, like that of iron-
siderophore complexes, is an active transport process requiring a specific outer membrane …

Vitamin B12 (CN-Cbl) and iron-siderophore complexes are transported into Escherichia coli
in two energy-dependent steps. The first step is mediated by substrate-specific outer …

BtuB is an outer membrane protein responsible for the uptake of vitamin B 12 by Escherichia
coli. It belongs to a family of bacterial transport proteins that derive energy for transport by …

The import of essential organometallic micronutrients (such as iron-siderophores and
vitamin B12) across the outer membrane of Gram-negative bacteria proceeds via TonB …

Crystals of the apo form of the vitamin B12 and colicin receptor, BtuB, that diffract to 1.95 Å
have been grown by the membrane-based in meso technique. The structure of the protein …

Uptake of siderophores and vitamin B 12 through the outer membrane of Escherichia coli is
effected by an active transport system consisting of several outer membrane receptors and a …