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Infect. Immun., 12 1997, 4984-4988, Vol 65, No. 12
M Trucksis, TL Conn, A Fasano and JB Kaper
Accessory cholera enterotoxin (Ace) is a recently identified toxin of
Vibrio cholerae. Preliminary studies using crude toxin extracts in animal
models indicate that Ace increases transcellular ion transport, which is
proposed to contribute to diarrhea in cholera. The lack of purified toxin
has hindered elucidation of the mechanism of action of Ace. In this study,
ace was cloned and was expressed in and secreted by the methylotrophic
yeast Pichia pastoris. Secreted toxin constituted 50% of the total
supernatant protein from Pichia pastoris. Presumed monomer and dimer forms
with molecular masses of 9 and 18 kDa, respectively, were observed. The
18-kDa form predominated. Biological activity was assayed by studying ion
fluxes across epithelial membranes in Ussing chambers. Among the
characteristics of Ace was the unusual property of staining with silver but
not Coomassie blue stain. To our knowledge this is the first report of a
biologically active bacterial toxin produced with the P. pastoris system.
The purified protein may now be used in studies of the mechanism of action
of Ace in physiologic systems.
Copyright © 1997, American Society for Microbiology
Production of Vibrio cholerae accessory cholera enterotoxin (Ace) in the yeast Pichia pastoris
Department of Medicine, University of Maryland School of Medicine, and Medical Science, Veterans Affairs Medical Center, Baltimore 21201, USA. mtrucksi@umppa1.ab.umd.edu
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