Lm. Skinner et Mp. Jackson, INHIBITION OF PROKARYOTIC TRANSLATION BY THE SHIGA TOXIN ENZYMATIC SUBUNIT, Microbial pathogenesis, 24(2), 1998, pp. 117-122
Shiga toxin, produced by Shigella dysenteriae serotype I: is a member
of the large family of ribosome-inactivating proteins (RIPs) which are
primarily produced by plants. All RIPs are rRNA N-glycosidases which
inactivate ribosomes through the removal of a specific adenine residue
from the well-conserved aminoacyl-tRNA-accepting loop of rRNA. As a t
ype II RIP, STX is believed to have little effect on prokaryotic ribos
omes. However, we have demonstrated that over-expression of the STX en
zymatic (Al) polypeptide which lacks a signal sequence caused a reduce
d rate of growth of its Escherichia coil host. Over-expression of the
same StxA1 polypeptide with a catalytic site substitution had no effec
t on the growth of E. coil. In addition, purified StxA1 was an inhibit
or of prokaryotic protein synthesis as assessed using an in vitro tran
scription and translation assay. The specific activity of StxA1 was si
gnificantly higher than ricin, which is another type II RIP, with both
eukaryotic and prokaryotic translation systems. (C) 1998 Academic Pre
ss Limited.