Intimin
Encyclopedia
Intimin is a virulence factor
(adhesin
) of EPEC (e.g. E. coli O127:H6) and EHEC (e.g. E. coli O157:H7) E. coli strains. It is an attaching and effacing (A/E) protein which with other virulence factors is responsible for enteropathogenic and enterohaemorrhagic
diarrhoea.
According to a TIME magazine Q & A story with Martin Wiedmann, a professor of food science
at Cornell University
, the strain E. coli O104:H21, a type of which may be implicated in the June 2011 E. coli outbreak (officials are now saying it is another new strain, E. coli O104:H4) is highly unusual because it has never posed a major outbreak threat before- and had never been seen outside of the original 1980s and 1990s cases in the Central African Republic and South Korea and several other isolated cases. Further, it is both very enterohemorrhagic
- perhaps more even than the more well-known E. coli O157:H7 strain- as well as remarkably adhesive (enteroaggregative) to the cell gut (despite the apparent lack of the gene that produces intimin). It is also resistant to many antibiotics that kill other E. coli strains, though this is not done as much anymore since upon the killing of the E. coli more virulence usually results (perhaps because when the cells collapse, there is release of more enterohemorrhagic
shiga toxin
).
<
Intimin is expressed on the bacterial cell surface where it can bind to its receptor Tir
(Translocated intimin receptor). Tir, along with over 25 other bacterial proteins, is secreted from attaching and effacing E. coli directly into the cytoplasm of intestinal epithelial cells by a Type three secretion system
. Once within the cytoplasm of the host cell, Tir is inserted into the plasma membrane, allowing surface exposure and intimin binding.
Virulence factor
Virulence factors are molecules expressed and secreted by pathogens that enable them to achieve the following:* colonization of a niche in the host...
(adhesin
Adhesin
Adhesins are cell-surface components or appendages of bacteria that facilitate bacterial adhesion or adherence to other cells or to inanimate surfaces. Adhesins are a type of virulence factor....
) of EPEC (e.g. E. coli O127:H6) and EHEC (e.g. E. coli O157:H7) E. coli strains. It is an attaching and effacing (A/E) protein which with other virulence factors is responsible for enteropathogenic and enterohaemorrhagic
Enterohemorrhagic
Enterohemorrhagic microorganisms are those that, as part of their pathogenesis, cause bloody diarrhea and colitis. While many pathogens are enterohemorrhagic, most cases observed are derived of E. coli serotype O157:H7. The E. coli O104:H4 strain identified as the cause of the 2011 outbreak in...
diarrhoea.
According to a TIME magazine Q & A story with Martin Wiedmann, a professor of food science
Food science
Food science is a study concerned with all technical aspects of foods, beginning with harvesting or slaughtering, and ending with its cooking and consumption, an ideology commonly referred to as "from field to fork"...
at Cornell University
Cornell University
Cornell University is an Ivy League university located in Ithaca, New York, United States. It is a private land-grant university, receiving annual funding from the State of New York for certain educational missions...
, the strain E. coli O104:H21, a type of which may be implicated in the June 2011 E. coli outbreak (officials are now saying it is another new strain, E. coli O104:H4) is highly unusual because it has never posed a major outbreak threat before- and had never been seen outside of the original 1980s and 1990s cases in the Central African Republic and South Korea and several other isolated cases. Further, it is both very enterohemorrhagic
Enterohemorrhagic
Enterohemorrhagic microorganisms are those that, as part of their pathogenesis, cause bloody diarrhea and colitis. While many pathogens are enterohemorrhagic, most cases observed are derived of E. coli serotype O157:H7. The E. coli O104:H4 strain identified as the cause of the 2011 outbreak in...
- perhaps more even than the more well-known E. coli O157:H7 strain- as well as remarkably adhesive (enteroaggregative) to the cell gut (despite the apparent lack of the gene that produces intimin). It is also resistant to many antibiotics that kill other E. coli strains, though this is not done as much anymore since upon the killing of the E. coli more virulence usually results (perhaps because when the cells collapse, there is release of more enterohemorrhagic
Enterohemorrhagic
Enterohemorrhagic microorganisms are those that, as part of their pathogenesis, cause bloody diarrhea and colitis. While many pathogens are enterohemorrhagic, most cases observed are derived of E. coli serotype O157:H7. The E. coli O104:H4 strain identified as the cause of the 2011 outbreak in...
shiga toxin
Shiga toxin
Shiga toxins are a family of related toxins with two major groups, Stx1 and Stx2, whose genes are considered to be part of the genome of lambdoid prophages. The toxins are named for Kiyoshi Shiga, who first described the bacterial origin of dysentery caused by Shigella dysenteriae. The most common...
).
<
Intimin is expressed on the bacterial cell surface where it can bind to its receptor Tir
Tir (receptor)
Tir is an essential component in the adherence of the enteropathogenic Escherichia coli and enterohemorraghic Escherichia coli to the cells lining the small intestine. To aid attachment, both EPEC and EHEC possess the ability to reorganise the host cell actin cytoskeleton via the secretion of...
(Translocated intimin receptor). Tir, along with over 25 other bacterial proteins, is secreted from attaching and effacing E. coli directly into the cytoplasm of intestinal epithelial cells by a Type three secretion system
Type three secretion system
Type three secretion system is a protein appendage found in several Gram-negative bacteria....
. Once within the cytoplasm of the host cell, Tir is inserted into the plasma membrane, allowing surface exposure and intimin binding.
External links
- http://ca.expasy.org/cgi-bin/get-sprot-entry?P43261 UniProtUniProtUniProt is a comprehensive, high-quality and freely accessible database of protein sequence and functional information, many of which are derived from genome sequencing projects...
/Swiss-Prot page on Intimin