Open AccessRandom and directed mutagenesis to elucidate the functional importance of helix II and F-989 in the C-terminal secretion signal of Escherichia coli hemolysin
Author(s) -
Christian Chervaux,
I. B. Holland
Publication year - 1996
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.178.4.1232-1236.1996
Subject(s) - biology , mutagenesis , helix (gastropod) , escherichia coli , site directed mutagenesis , secretion , signal peptide , genetics , biochemistry , protein secondary structure , peptide sequence , mutation , gene , mutant , ecology , snail
The HlyA secretion signal sequence of approximately 46 residues is predicted to contain helix I and an amphipathic helix II separated by a short loop including the conserved Phe residue, F-989. All nine substitutions of Phe-989 drastically reduce secretion of HlyA. Directed mutagenesis identified a functional hot spot, EISK, in helix II. However, genetic analysis did not provide strong support for a functional helix II; rather, the results emphasized that individual residues, for example, E-978 and F-989, are essential irrespective of a specific secondary structure.