Involvement of a phospholipase C in the hemolytic activity of a clinical strain of Pseudomonas fluorescens.
BACKGROUND
Pseudomonas fluorescens is a ubiquitous Gram-negative bacterium frequently encountered in hospitals as a contaminant of injectable material and surfaces. This psychrotrophic bacterium, commonly described as unable to grow at temperatures above 32 degrees C, is now considered non pathogenic. We studied a recently identified clinical strain of P. fluorescens biovar I, MFN1032, which is considered to cause human lung infection and can grow at 37 degrees C in laboratory conditions.


RESULTS
We found that MFN1032 secreted extracellular factors with a lytic potential at least as high as that of MF37, a psychrotrophic strain of P. fluorescens or the mesophilic opportunistic pathogen, Pseudomonas aeruginosa PAO1. We demonstrated the direct, and indirect - through increases in biosurfactant release - involvement of a phospholipase C in the hemolytic activity of this bacterium. Sequence analysis assigned this phospholipase C to a new group of phospholipases C different from those produced by P. aeruginosa. We show that changes in PlcC production have pleiotropic effects and that plcC overexpression and plcC extinction increase MFN1032 toxicity and colonization, respectively.


CONCLUSIONS
This study provides the first demonstration that a PLC is involved in the secreted hemolytic activity of a clinical strain of Pseudomonas fluorescens. Moreover, this phospholipase C seems to belong to a complex biological network associated with the biosurfactant production.
Rossignol
Gaelle
G
Laboratory of Cold Microbiology, UPRES EA 4312, University of Rouen, 55 rue Saint Germain, 27000 Evreux, France.
Merieau
Annabelle
A
Guerillon
Josette
J
Veron
Wilfried
W
Lesouhaitier
Olivier
O
Feuilloley
Marc G J
MG
Orange
Nicole
N
D000818:Animals; D001952:Bridged-Ring Compounds / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D023061:Gene Order; D006461:Hemolysis; D008070:Lipopolysaccharides / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009636:Norbornanes; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010740:Phospholipases / Q000378:metabolism; D011551:Pseudomonas fluorescens / Q000201:enzymology* / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013501:Surface-Active Agents / Q000378:metabolism; D013696:Temperature; D013859:Thiocarbamates; D013871:Thiones / Q000494:pharmacology; D010738:Type C Phospholipases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D001952:Bridged-Ring Compounds; D008070:Lipopolysaccharides; D009636:Norbornanes; D010726:Phosphodiesterase Inhibitors; D013501:Surface-Active Agents; D013859:Thiocarbamates; D013871:Thiones; C046498:tricyclodecane-9-yl-xanthogenate; D010740:Phospholipases; D010738:Type C Phospholipases