Lethal factor is one of many bacterial proteins known as exotoxins. Most of these proteins are enzymatic and cause damage to host cells by disrupting cellular processes. Lethal factor has structural homology with Bacillus cereus toxin vegitative insecticidal protein 2 (VIP2). Most Bacillus secreted proteins share this structural homology indicating close evolutionary relationships. Although Bacillus cereus does not have insecticide properties, it's relative, Bacillus thuringiensis does.
Bacillus cereus, a relative of B. anthracis is famously known for causing "fried rice syndrome"-an uncomfortable GI illness acquired from consuming buffet style rice that has been sitting at room temperature for extended periods of time. The bacteria produces a plethora of toxic proteins, alike Bacillus anthracis. Three of these proteins in particular, cytolysin K (Cytk), non-hemolytic enterotoxin (Nhe), and hemolysin BL (Hbl) form pores in human GI tracts.
Furthermore, Bacillus cereus VIP2 has as NAD binding domain and has ADP ribosylating activity. This is characteristic of the enzyme. Lethal factor however lacks a critical glutamic acid and does not have this activity. Instead, the "VIP2 like" domain II in Bacillus anthracis acts as a connector between domains 1, 3, and 4 as well as plays a role in substrate docking. Nonetheless, shared homology in between B. anthracis, B. cereus, and B. thuringiensis can be seen in through comparison of VIP2 like structures. The structural homology between B. anthracis, B. cereus is so similar that superimposed images of B. anthracis domain II and VIP2 showed sequence identity of 15%. Although not much is known about the evolutionary split between these two species proteins, the similarities in VIP2 structure has opened doors for further research on the evolutionary relationship between Bacillus exotoxins.
- Patrick: Anthrax Toxin: Introduction
- Patrick: Anthrax Toxin: Biological Function
- Patrick: Anthrax Toxin: Biosynthesis
- Patrick: Anthrax Toxin: Gene Sequence
- Patrick: Anthrax Toxin: Amino Acid Sequence and Composition
- Patrick: Anthrax Toxin: Secondary and Tertiary Structure
- Patrick: Anthrax Toxin: Domains and Structural Motifs
- Patrick: Anthrax Toxin: Interactions with macromolecules and small molecules
- Patrick: Anthrax Toxin: Molecular biodiversity and evolution
- Patrick: Anthrax Toxin: PyMOL Images
- Patrick: Anthrax Toxin: Literature Review
- Patrick: Anthrax Toxin: Useful online resources
Han, S., Craig, JA., Putnam, CD., Carozzi, NB., Tainer, JA. 1999. Evolution and mechanism from structures of an ADP-ribosylating toxin and NAD complex. Nature Structural Biology. 6:932-936.
Helgason, E., Okstad O., Kolsto, A. 2000. Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis—One Species on the Basis of Genetic Evidence.Applied and Environmental Microbiology. 66(6): 2827-2630.
Ivanova, N. et al. 2003. Genome sequence of Bacillus cereus and comparative analysis with Bacillus anthracis. Nature. 423: 87-91