Newcastle University Drylab/7 June 2008

Nina
Bacillus anthracis

Today I will attempt to uncover a unique peptide associated with a two component system in Bacillus anthracis.

It has been suggested that Bacillus anthracis is a subspecies of Bacillus cereus. However one obvious difference between the two genomes is anthracis has truncated or degraded HKs and RRs and TCS related genes. This maybe due to the specific warmblooded environment that this pathogen requires. In contrast, Bacillus cereus and many other bacteria exploit the two component system to sense and respond to hostile and changing environments. Therefore in comparison other similar bacteria have a larger set of these particular proteins.

However, I did come across evidence of the LuxS quorum sensing system. This produces the autoinducer A1-2.

The problem with the luxS/AI-2 system (similar problem to that of Clostridium difficile). The LuxS/AI-2 (autoinducer-2) is a signalling molecule that functions in **interspecies** communication by regulating niche-specific genes with diverse functions in various bacteria, often in response to population density. LuxS (S-ribosylhomocysteinase; ) is an autoinducer-production protein that has a metabolic function as a component of the activated methyl cycle. LuxS converts S-ribosylhomocysteine to homocysteine and 4,5-dihydroxy-2,3-pentanedione (DPD); DPD can then spontaneously cyclise to active AI-2. Therefore as with Clostridium difficile, the luxS/AI-2 peptide will not be able to specifically diagnose anthrax. However to confirm this statement I performed a few bioinformatic analyses on the peptide.

Used kegg to retrieve the luxS gene loci from the completed Bacillus anthracis genome (ames strain). Added 1000 +/- to the nucleotide count to include all potential associated genes.

Blasted the sequence in nBLAST.

Retrieved several other Bacilli species as well as anthracis with 100% similarity.

Conclusion: I would suspect using Bacillus anthracis would be futile. I cannot locate a unique quorum sensing peptide. In addition, this is a fairly badly annotated genome with degraded two component system related genes.

Brilliant link to find out which bacteria use which two component systems;

http://www.genome.jp/kegg/pathway/ko/ko02020.html