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Topology and function of the integral membrane protein conferring immunity to colicin A
Author(s) -
Geli V.,
Baty D.,
Pattus F.,
Lazdunski C.
Publication year - 1989
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.1365-2958.1989.tb00216.x
Subject(s) - colicin , biology , transmembrane protein , integral membrane protein , membrane topology , topology (electrical circuits) , fusion protein , immunity , mutagenesis , function (biology) , transmembrane domain , peptide sequence , microbiology and biotechnology , membrane protein , gene , genetics , escherichia coli , immune system , membrane , mutation , receptor , mathematics , combinatorics , recombinant dna
Summary The topology of the integral membrane protein Cai (colicin A immunity protein), which is required to protect producing cells from the pore‐forming colicin A, was analysed using fusions to alkaline phosphatase. The properties of these fusion proteins support the model for Cai topology previously proposed on theoretical grounds. The protein was found to contain four transmembrane sequences and its N ‐and C ‐terminal regions were found to be directed towards the cytoplasm. Oligonucleotide‐directed mutagenesis and sequence comparisons between Cai, Cbi (colicin B immunity protein), and Cni (colicin N immunity protein) were carried out to determine the functional regions of Cai. The possible roles of the various regions of Cai in its protective function and in its topological organization are discussed.