Food Biochemistry and Food Processing

712

Table 31.2.

(Continued

)

Organism

Toxin Name

Toxin Type

Size of Toxin

Effect/Mode of Action of Toxin

-hemolysin

Thiol-activated

33 kDa

These proteins bind to high affinity

cytolysin

(unidentified) receptors at low concentrations (



200 nM), and

nonspecifically to cell membranes at higher concentrations (



200 nM). The

hemolysin preferentially attacks endothelial cells and thrombocytes, forming pores and leading to pulmonary edema (Menestrina et al. 2001).

S. typhimurium

TTSS-1

Type III-secretion

Multiple

A protein transport system involved in

system

translocating a number of effector proteins into host cells. TTSS-1 moves SipA, SopA, SopB, SopD, and SopE2 intohost cells. This elicits the infiltration of neutrophils into the intestine through the induction of chemoattractant chemokinesecretion into the ileal tissue, resulting in diarrhea (Zhang et al. 2003).

Y. enterocolitica

Y-ST

Enterotoxin

2 kDa

Toxin binds to guanylate cyclase in the

brush border of the intestine, and mediates secretion of fluid into the intestine, leading to diarrhea (Takeda et al. 1999, Yoshino et al. 1995).

Yops proteins

Yersinia

outer

20.8–81.7

YopE, YopH, and Yop-O have sequence

proteins—

kDa

similarity to

Shigella

-hemolysins

unconventional

(Cornelis

(Dobrindt and Hacker 1999). They are

toxins

et al.

part of a Type III secretion system,

1998)

which on contact with the host cell interrupts signal transduction pathways inthe cells (Carnoy and Simonet 1999). The proteins also interfere with phagocytosis by host cells (Grosdent et al. 2002)