Bacillus anthracis is an endospore-forming, Gram-positive rod-shaped bacterium. Within the genus Bacillus, B. anthracis belongs to the Bacillus cereus group, which includes the pathogens B. cereus and B. thuringiensis. B. anthracis has many characteristics of a soil bacterium, and is considered to have evolved from a B. cereus type ancestor through acquisition of plasmid-encoded virulence factors.
Long regarded as the preferred biological warfare agent, Bacillus anthracis is the causative agent of anthrax. Its potential for use as a bioweapon was infamously demonstrated by the autumn 2001 anthrax letter attacks in the U.S. more >>
For each genome both coding and non-coding features are predicted, and have been made available for retrieval and analysis. Each coding region is assigned descriptive functional curation using one of three distinct methods, distinguishable on individual gene pages, and as outlined in the protocols section. << hide
Lethal factor is a metaloproteinase that cleaves mitogen-activated protein kinase, while edema factor is an adenylate cyclase that increases cAMP levels in host cells. Also located on pXO1 is an operon of spore germination proteins which are thought to allow the bacterium to germinate within phagocytic cells. Two regulatory genes important in virulence also reside on pXO1: AtxA activates transcription of both toxin and capsule biosyntheis genes, while PagR represses the expression of AtxA. The polyglutamate capsule biosynthesis operon capABCDE is located on plasmid pXO2. Expression of proteins from this operon is important to virulence as they synthesize a capsule that allows the bacterium to resist phagocytosis by the host. Two postive regulators of the cap operon, AcpA and AcpB, are also located on pXO2.
The chromosome encodes virulence factors orthologous to those in other gram positive bacteria. These include fibronectin-binding proteins involved in host adhesion; potential cytolysins and a putative internalin involved in host invasion; and a siderophore biosynthesis operon asbABCDEF crucial to scavenging iron from the host and allowing successful colonization. Several additional genes located on the chromosome allow the bacterium to evade host defense mechanisms. Two immune inhibitor A metalloproteinases degrade antibacterial proteins secreted by the host; a putative lysylphosphatidylglycerol synthetase MprF and peptidoglycan biosynthesis operon are also thought to contribute to host defense evasion. Recent analysis of the Bacillus anthracis secretome has identified secreted chromosomal proteins with features characteristic of virulence factors. << hide