Identification of a new hemolysin from diarrheal isolate SSU of Aeromonas hydrophila.
A clinical strain SSU of Aeromonas hydrophila produces a potent cytotoxic enterotoxin (Act) with cytotoxic, enterotoxic, and hemolytic activities. A new gene, which encoded a hemolysin of 439-amino acid residues with a molecular mass of 49 kDa, was identified. This hemolysin (HlyA) was detected based on the observation that the act gene minus mutant of A. hydrophila SSU still had residual hemolytic activity. The new hemolysin gene (hlyA) was cloned, sequenced, and overexpressed in Escherichia coli. The hlyA gene exhibited 96% identity with its homolog found in a recently annotated genome sequence of an environmental isolate, namely the type strain ATCC 7966 of A. hydrophila subspecies hydrophila. The hlyA gene did not exhibit any homology with other known hemolysins and aerolysin genes detected in Aeromonas isolates. However, this hemolysin exhibited significant homology with hemolysin of Vibrio vulnificus as well as with the cystathionine beta synthase domain protein of Shewanella oneidensis. The HlyA protein was activated only after treatment with trypsin and the resulting hemolytic activity was not neutralizable with antibodies to Act. The presence of the hlyA gene in clinical and water Aeromonas isolates was investigated and DNA fingerprint analysis was performed to demonstrate its possible role in Aeromonas virulence.
Erova
Tatiana E
TE
Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA.
Sha
Jian
J
Horneman
Amy J
AJ
Borchardt
Mark A
MA
Khajanchi
Bijay K
BK
Fadl
Amin A
AA
Chopra
Ashok K
AK
D016980:Aeromonas hydrophila / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D003001:Cloning, Molecular; D016172:DNA Fingerprinting / Q000379:methods; D003967:Diarrhea / Q000382:microbiology*; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology; D006460:Hemolysin Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006461:Hemolysis; D006801:Humans; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA
D001426:Bacterial Proteins; D006460:Hemolysin Proteins