Cloning, sequencing, and role in virulence of two phospholipases (A1 and C) from mesophilic Aeromonas sp. serogroup O:34.
Two different representative recombinant clones encoding Aeromonas hydrophila lipases were found upon screening on tributyrin (phospholipase A1) and egg yolk agar (lecithinase-phospholipase C) plates of a cosmid-based genomic library of Aeromonas hydrophila AH-3 (serogroup O34) introduced into Escherichia coli DH5alpha. Subcloning, nucleotide sequencing, and in vitro-coupled transcription-translation experiments showed that the phospholipase A1 (pla) and C (plc) genes code for an 83-kDa putative lipoprotein and a 65-kDa protein, respectively. Defined insertion mutants of A. hydrophila AH-3 defective in either pla or plc genes were defective in phospholipase A1 and C activities, respectively. Lecithinase (phospholipase C) was shown to be cytotoxic but nonhemolytic or poorly hemolytic. A. hydrophila AH-3 plc mutants showed a more than 10-fold increase in their 50% lethal dose on fish and mice, and complementation of the plc single gene on these mutants abolished this effect, suggesting that Plc protein is a virulence factor in the mesophilic Aeromonas sp. serogroup O:34 infection process.
Departamento de Microbiología, Facultad de Biología, Universidad de Barcelona, 08071 Barcelona, Spain.
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Merino
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Aguilar
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Nogueras
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Regue
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Swift
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Tomás
D000333:Aeromonas / Q000201:enzymology* / Q000472:pathogenicity; D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000737:chemistry; D051379:Mice; D009154:Mutation; D010740:Phospholipases; D010741:Phospholipases A / Q000737:chemistry / Q000235:genetics / Q000633:toxicity*; D054466:Phospholipases A1; D010738:Type C Phospholipases / Q000737:chemistry / Q000235:genetics / Q000633:toxicity*; D014774:Virulence
D004269:DNA, Bacterial; D010740:Phospholipases; D010741:Phospholipases A; D054466:Phospholipases A1; D010738:Type C Phospholipases