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Inactivation of colicin Y by intramembrane helix–helix interaction with its immunity protein
Author(s) -
Šmajs David,
Doležalová Magda,
Macek Pavel,
Žídek Lukáš
Publication year - 2008
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2008.06662.x
Subject(s) - colicin , mutant , escherichia coli , helix (gastropod) , antiparallel (mathematics) , mutagenesis , biology , amino acid , peptide sequence , protein structure , gene , genetics , biochemistry , chemistry , ecology , physics , quantum mechanics , snail , magnetic field
The construction of hybrids between colicins U and Y and the mutagenesis of the colicin Y gene ( cya ) have revealed amino acid residues important for interactions between colicin Y and its cognate immunity protein (Cyi). Four such residues (I578, T582, Y586 and V590) were found in helices 8 and 9 of the colicin Y pore‐forming domain. To verify the importance of these residues, the corresponding amino acids in the colicin B protein were mutated to the residues present in colicin Y. An Escherichia coli strain with cloned colicin Y immunity gene ( cyi ) inactivated this mutant, but not the wild‐type colicin B. In addition, interacting amino acid pairs in Cya and Cyi were identified using a set of Cyi point mutant strains. These data are consistent with antiparallel helix–helix interactions between Cyi helix T3 and Cya helix 8 of the pore‐forming domain as a molecular mechanism of colicin Y inactivation by its immunity protein.