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Iron transport and signaling in Escherichia coli
Author(s) -
Braun Volkmar,
Braun Michael
Publication year - 2002
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(02)03185-x
Subject(s) - siderophore , bacterial outer membrane , cytoplasm , escherichia coli , transport protein , biochemistry , chemiosmosis , electron transport chain , periplasmic space , inner membrane , bacteria , chemistry , membrane transport , membrane protein , membrane transport protein , biophysics , biology , membrane , gene , atp synthase , genetics
Bacteria solve the iron supply problem caused by the insolubility of Fe 3+ by synthesizing iron‐complexing compounds, called siderophores, and by using iron sources of their hosts, such as heme and iron bound to transferrin and lactoferrin. Escherichia coli , as an example of Gram‐negative bacteria, forms sophisticated Fe 3+ –siderophore and heme transport systems across the outer membrane. The crystal structures of three outer membrane transport proteins now allow insights into energy‐coupled transport mechanisms. These involve large long‐range structural transitions in the transport proteins in response to substrate binding, including substrate gating. Energy is provided by the proton motive force of the cytoplasmic membrane through the activity of a protein complex that is inserted in the cytoplasmic membrane and that contacts the outer membrane transporters. Certain transport proteins also function in siderophore‐mediated signaling cascades that start at the cell surface and flow to the cytoplasm to initiate transcription of genes encoding proteins for transport and siderophore biosynthesis.