Random and directed mutagenesis to elucidate the functional importance of helix II and F-989 in the C-terminal secretion signal of Escherichia coli hemolysin.
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.
Chervaux
C
C
Institut de Génétique et Microbiologie, Université Paris Sud.
Holland
I B
IB
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D004252:DNA Mutational Analysis; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D017433:Protein Structure, Secondary; D013329:Structure-Activity Relationship
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; C036507:Hlya protein, E coli