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Vitamin B 12 transport in Escherichia coli : energy coupling between membranes
Author(s) -
Kadner R. J.
Publication year - 1990
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1990.tb00562.x
Subject(s) - bacterial outer membrane , biology , escherichia coli , chemiosmosis , membrane transport protein , membrane , transport protein , mutagenesis , membrane protein , biochemistry , membrane transport , biophysics , inner membrane , microbiology and biotechnology , mutation , gene , atp synthase
Summary Cells of Escherichia coli possess high‐affinity active transport systems of vitamin B 12 and iron‐siderophore complexes. Specific outer‐membrane proteins carry out the energy‐dependent transport across the outer membrane, in conjunction with the TonB coupling protein. Mutagenesis experiments have identified a conserved region near the amino‐terminus of the outer‐membrane transporters that is necessary for energy‐coupled transport. The ability of extragenic suppressor mutations in tonB to correct the transport defect indicates that TonB couples the proton‐motive force to the outer‐membrane proteins by direct contact.