Quorum sensing-dependent regulation and blockade of exoprotease production in Aeromonas hydrophila.
In Aeromonas hydrophila, the ahyI gene encodes a protein responsible for the synthesis of the quorum sensing signal N-butanoyl-L-homoserine lactone (C4-HSL). Inactivation of the ahyI gene on the A. hydrophila chromosome abolishes C4-HSL production. The exoprotease activity of A. hydrophila consists of both serine protease and metalloprotease activities; in the ahyI-negative strain, both are substantially reduced but can be restored by the addition of exogenous C4-HSL. In contrast, mutation of the LuxR homolog AhyR results in the loss of both exoprotease activities, which cannot be restored by exogenous C4-HSL. Furthermore, a substantial reduction in the production of exoprotease by the ahyI+ parent strain is obtained by the addition of N-acylhomoserine lactone analogs that have acyl side chains of 10, 12, or 14 carbons. The inclusion of N-(3-oxododecanoyl)-L-homoserine lactone or N-(3-oxotetradecanoyl)-L-homoserine lactone at 10 microM in overnight cultures of A. hydrophila abolishes exoprotease production in azocasein assays and reduces the activity of all the exoprotease species seen in zymograms.
Swift
S
S
Institute of Infections and Immunity, Queen's Medical Centre, University of Nottingham, Nottingham, NG7 2UH, United Kingdom. simon.swift@nottingham.ac.uk
Lynch
M J
MJ
Fish
L
L
Kirke
D F
DF
Tomás
J M
JM
Stewart
G S
GS
Williams
P
P
D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000502:physiology; D016980:Aeromonas hydrophila / Q000201:enzymology / Q000472:pathogenicity*; D020689:Exopeptidases; D008666:Metalloendopeptidases / Q000378:metabolism; D009154:Mutation; D010447:Peptide Hydrolases / Q000096:biosynthesis*; D012697:Serine Endopeptidases / Q000378:metabolism; D014774:Virulence
C092312:N-butyrylhomoserine lactone; D020689:Exopeptidases; D010447:Peptide Hydrolases; D012697:Serine Endopeptidases; D008666:Metalloendopeptidases; D015107:4-Butyrolactone