Incomplete activation of Escherichia coli hemolysin (HlyA) due to mutations in the 3' region of hlyC.
Mutational analysis of the carboxy-terminal region of Escherichia coli HlyC was performed by site-directed mutagenesis. Replacement of residue Val-127 or Lys-129 reduced the activity of HlyC to about 30 or 60%, respectively, of that of the wild type, while replacement of Gly-128 reduced the activity to less than 1% of the wild-type level. Complete inactivation of HlyC was caused by a double mutation, replacement of Gly-128 with valine and of Lys-129 with isoleucine. Analysis of culture supernatants from mutants with reduced hemolytic activity by two-dimensional gel electrophoresis revealed the production and simultaneous secretion of nonacylated, monoacylated, and fully acylated HlyA forms, demonstrating impairment of the acylation reaction, possibly due to a decreased affinity of HlyC for the individual HlyA acylation sites.
Guzmán-Verri
C
C
Microbiology and Tumorbiology Centre (MTC), Karolinska Institute, Stockholm, Sweden.
García
F
F
Arvidson
S
S
D000215:Acylation; D000217:Acyltransferases; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D006460:Hemolysin Proteins / Q000235:genetics* / Q000378:metabolism*; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D017354:Point Mutation; D013329:Structure-Activity Relationship
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; C036507:Hlya protein, E coli; D046911:Macromolecular Substances; D000217:Acyltransferases; C092237:HlyC protein, E coli