Open AccessAnalysis of KdpC of the K + ‐transporting KdpFABC complex of Escherichia coli
Author(s) -
Gaßel Michael,
Altendorf Karlheinz
Publication year - 2001
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.2001.02048.x
Subject(s) - complementation , escherichia coli , clostridium acetobutylicum , protein subunit , biology , protein fragment complementation assay , transmembrane protein , plasmid , transmembrane domain , biochemistry , gene , mutant , butanol , receptor , ethanol
The Kdp complex, a high affinity ATP‐driven K + transport system of Escherichia coli , is composed of the four membrane‐bound subunits KdpF, KdpA, KdpB and KdpC. Whereas the role of KdpB (catalytical subunit), KdpA (K + ‐translocating subunit) and KdpF (stabilizing peptide) is well understood, the function of KdpC is still unknown. Therefore, a kdpC deletion strain was constructed and complementation experiments were performed using different kdpC constructs. Truncations of the kdpC gene revealed that only one derivative, which lacks base pairs coding for the four C‐terminal amino acids, was able to complement the chromosomal deletion of kdpC . Furthermore, complementation was also observed with kdpC of Mycobacterium tuberculosis , but not with kdpC from Clostridium acetobutylicum or Synechocystis sp. PCC6803. Sequence alignment of 17 different KdpC proteins led to the construction of hybrids between kdpC of E. coli and that of C. acetobutylicum . Complementation revealed that the N‐terminal transmembrane segment as well as the C‐terminal‐third of the protein can be exchanged between both species, but only one after the other. A simultaneous substitution of both regions was not possible.