Anthrax Lethal Factor

==Introduction==

'''Pertussis Toxins''' (PT) is a protein-based exotoxin and major virulence factor produced by the bacterium [http://en.wikipedia.org/wiki/Bordetella_pertussis ''Bordetella pertussis''].<ref name=Hazes>PMID: 8637000</ref> PT causes [http://en.wikipedia.org/wiki/Whooping_cough pertussis], which is also known at [http://www.youtube.com/watch?v=1PajbAKd8Kg whooping cough] and is highly contagious bacterial disease. The disease is caused by the bacterium colonizing the respiratory tract where it then establishes an infection.<ref name=Carbonetti>PMID: 14573656</ref> This disease had been characterized by severe coughing that can last up to six weeks and in some countries lasting nearly 100 days.<ref name=Carbonetti>PMID: 17418639</ref>It has been documented in some cases that PT can cause [http://en.wikipedia.org/wiki/Subconjunctival_hemorrhage subconjunctival hemorrhages], [http://en.wikipedia.org/wiki/Rib_fracture rib fractures], [http://en.wikipedia.org/wiki/Hernias hernias], fainting and [http://en.wikipedia.org/wiki/Vertebral_artery_dissection vertebral artery dissection].<ref name=cornia>PMID: 20736473</ref>

As of 2010, the worldwide incidence of whooping cough has been estimated to 48.5 million cases and nearly 295,000 deaths per year.<ref name=Bettiol>PMID: 20091541</ref> With that in mind, whooping cough can affect people of any age; however, before vaccines were available the disease was most common in infants and young children but now children are immunized and the high percentage of cases are seen among adolescents.

==Structure==

The [http://en.wikipedia.org/wiki/Pertussis_toxin pertussis toxin] has been characterized as being an AB toxin meaning that there are 2 subunits: A subunit possesses the enzyme activity and the B subunit possesses the receptor binding portion. PT in particular is an AB5 toxin consisting of a six-component protein complex, and the multiple subunits of the complex are not identical in composition.<ref name=Hazes>PMID: 8637000</ref> With that in mind, this protein is a hexamer containing a catalytic (S1) subunit that is tightly associated with the pentameric cell-binding component (B-oligomer).<ref name=Hazes>PMID: 8637000</ref> The S1 component is a single subunit <scene name='Pertussis_Toxin-ATP_Complex/Subunit_1/3'>S1 (chains A,G)</scene> while the B-oligomer is a pentamer composed of four types of subunits: <scene name='Pertussis_Toxin-ATP_Complex/Subunit_2/3'>S2 (chains B,H)</scene>, <scene name='Pertussis_Toxin-ATP_Complex/Subunit_3/5'>S3 (chains C,I)</scene>, two copies of <scene name='Pertussis_Toxin-ATP_Complex/Subunit_4/3'>S4 (chains D,E,J,K)</scene>, and <scene name='Pertussis_Toxin-ATP_Complex/Subunit_5/4'>S5 (chains F,L)</scene>.<ref name=Hazes>PMID: 8637000</ref> The overall structure of PT <scene name='Pertussis_Toxin-ATP_Complex/Whole_monomer/2'>multisubunit complex</scene>. These subunits are encoded by ptx genes, which are encoded on a large PT [http://en.wikipedia.org/wiki/Operon operon] that includes additional genes as well such as Pti genes. Together the PT and Pti proteins form the PT secretion complex and toxin itself.<ref name=Weiss>PMID: 8464913</ref>