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Anthrax Structure
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The anthrax toxin is made up of three
different proteins. The first protein, the PA constitutes what is known
as the carrier of the toxin. It is the PA that binds to the cell at
the Anthrax toxin receptor (ATR). Once bound to this receptor, the protein
undergoes a major conformational change. It is after this conformational
change whenthe two other proteinsbind. The next protein of the Anthrax
system is the edema factor (EF). The final protein is known as the LF
and was recently crystallized (Pannifer
et all, 2001) and thus a mechanism was proposed. Although all three
proteins enter the cell's cytoplasm, it is the EF and LF that cause
the cell toxicity.
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| Background |
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| Anthrax Structure |
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When the PA and the
LF bind, what is formed is known as the LeTx. Even without the addition
of EF, the LeTx can cause rapid death in animals. The LeTx, once inside
the cell, splits apart and thus releases the LF. LF is a zinc metalloprotease
that cleaves the several different forms of the MAPKK. LF is a four-domain
protein. It is on the first domain where the LF binds to the PA. The second
domain is relatively inactive, yet may contain a site for the binding of
NAD. Domain three is the most likely place for the active site of LF. It
is this site that interferes with the MAPKK. Domain four is the catalytic
center of the protein, as it binds tightly to a Zinc cation(Pannifer
et all, 2001). |
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Figure
2--The four domain protein of LF |
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Figure 3 --The
Structure of PA |
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Figure 3a--The regions of PA, EF and LF |
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