Affiliation:
1. Departamento de Sanidad Animal, Microbiologı́a e Inmunologı́a, Facultad de Veterinaria, Universidad de León, 24071 León, Spain
Abstract
ABSTRACT
Aeromonas hydrophila
is an opportunistic pathogen and the leading cause of fatal hemorrhagic septicemia in rainbow trout. A gene encoding an elastolytic activity,
ahyB
, was cloned from
Aeromonas hydrophila
AG2 into pUC18 and expressed in
Escherichia coli
and in the nonproteolytic species
Aeromonas salmonicida
subsp.
masoucida
. Nucleotide sequence analysis of the
ahyB
gene revealed an open reading frame of 1,764 nucleotides with coding capacity for a 588-amino-acid protein with a molecular weight of 62,728. The first 13 N-terminal amino acids of the purified protease completely match those deduced from DNA sequence starting at AAG (Lys-184). This finding indicated that AhyB is synthesized as a preproprotein with a 19-amino-acid signal peptide, a 164-amino-acid N-terminal propeptide, and a 405-amino-acid intermediate which is further processed into a mature protease and a C-terminal propeptide. The protease hydrolyzed casein and elastin and showed a high sequence similarity to other metalloproteases, especially with the mature form of the
Pseudomonas aeruginosa
elastase (52% identity),
Helicobacter pylori
zinc metalloprotease (61% identity), or proteases from several species of
Vibrio
(52 to 53% identity). The gene
ahyB
was insertionally inactivated, and the construct was used to create an isogenic
ahyB
mutant of
A. hydrophila
. These first reports of a defined mutation in an extracellular protease of
A. hydrophila
demonstrate an important role in pathogenesis.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
128 articles.
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