In vivo quantification of the secretion rates of the hemolysin A Type I secretion system.
Type 1 secretion systems (T1SS) of Gram-negative bacteria secrete a broad range of substrates into the extracellular space. Common to all substrates is a C-terminal secretion sequence and nonapeptide repeats in the C-terminal part that bind Ca(2+) in the extracellular space, to trigger protein folding. Like all T1SS, the hemolysin A (HlyA) T1SS of Escherichia coli consists of an ABC transporter, a membrane fusion protein and an outer membrane protein allowing the one step translocation of the substrate across both membranes. Here, we analyzed the secretion rate of the HlyA T1SS. Our results demonstrate that the rate is independent of substrate-size and operates at a speed of approximately 16 amino acids per transporter per second. We also demonstrate that the rate is independent of the extracellular Ca(2+) concentration raising the question of the driving force of substrate secretion by T1SS in general.
Institute of Biochemistry, Heinrich-Heine-Universitaet, 40225 Duesseldorf, Germany.
Michael H H
MH
Lenders
Institute of Biochemistry, Heinrich-Heine-Universitaet, 40225 Duesseldorf, Germany.
Tobias
T
Beer
Institute of Biochemistry, Heinrich-Heine-Universitaet, 40225 Duesseldorf, Germany.
Sander H J
SH
Smits
Institute of Biochemistry, Heinrich-Heine-Universitaet, 40225 Duesseldorf, Germany.
Lutz
L
Schmitt
D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D001692:Biological Transport / Q000235:genetics*; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D006460:Hemolysin Proteins / Q000235:genetics* / Q000378:metabolism; D017510:Protein Folding; D000069177:Type I Secretion Systems / Q000235:genetics* / Q000378:metabolism
D018528:ATP-Binding Cassette Transporters; D002135:Calcium-Binding Proteins; D006460:Hemolysin Proteins; D000069177:Type I Secretion Systems; D002118:Calcium